Release v0.22.0

background, crop, embed, ignoreAspectRatio, max, min, withoutEnlargement

.editorconfig

@@ -0,0 +1,12 @@
+# http://editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false

.gitattributes

@@ -0,0 +1 @@
+src/libvips/* linguist-vendored

.gitignore

@@ -1,9 +1,15 @@
 build
 node_modules
-coverage
+/coverage
 test/bench/node_modules
-test/fixtures/output.*
+test/fixtures/output*
 test/leak/libvips.supp
-
-# Mac OS X
+test/saliency/report.json
+test/saliency/Image*
+test/saliency/[Uu]serData*
+!test/saliency/userData.js
+vendor
+.gitattributes
 .DS_Store
+.nyc_output
+package-lock.json

.jshintignore

@@ -1,3 +0,0 @@
-node_modules
-test/bench/node_modules
-coverage

.jshintrc

@@ -1,8 +0,0 @@
-{
-  "strict": true,
-  "node": true,
-  "globals": {
-    "describe": true,
-    "it": true
-  }
-}

.npmignore

@@ -1,8 +1,15 @@
 build
 node_modules
 coverage
-.jshintignore
-.jshintrc
+.editorconfig
+.gitattributes
 .gitignore
 test
 .travis.yml
+appveyor.yml
+mkdocs.yml
+docs/css/
+vendor
+.prebuildrc
+.nyc_output
+CONTRIBUTING.md

.prebuildrc

@@ -0,0 +1,4 @@
+{
+  "include-regex": "(sharp\\.node|libvips-cpp\\.dll)",
+  "strip": true
+}

.travis.yml

@@ -1,8 +1,79 @@
-language: node_js
-node_js:
-  - "0.10"
-  - "0.11"
-before_install:
-  - curl -s https://raw.githubusercontent.com/lovell/sharp/master/preinstall.sh | sudo bash -
-after_success:
-  - cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js
+matrix:
+  include:
+    - name: "Linux (glibc) - Node 6"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "6"
+    - name: "Linux (glibc) - Node 8"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "8"
+    - name: "Linux (glibc) - Node 10"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "10"
+      after_success:
+        - npm install coveralls
+        - cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js
+    - name: "Linux (glibc) - Node 11"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "11"
+    - name: "Linux (musl) - Node 8"
+      os: linux
+      dist: trusty
+      sudo: true
+      language: minimal
+      before_install:
+        - sudo docker run -dit --name sharp --env CI --env PREBUILD_TOKEN --volume "${PWD}:/mnt/sharp" --workdir /mnt/sharp node:8-alpine
+        - sudo docker exec sharp apk add build-base git python2 --update-cache
+      install: sudo docker exec sharp sh -c "npm install --unsafe-perm"
+      script: sudo docker exec sharp sh -c "npm test"
+    - name: "Linux (musl) - Node 10"
+      os: linux
+      dist: trusty
+      sudo: true
+      language: minimal
+      before_install:
+        - sudo docker run -dit --name sharp --env CI --env PREBUILD_TOKEN --volume "${PWD}:/mnt/sharp" --workdir /mnt/sharp node:10-alpine
+        - sudo docker exec sharp apk add build-base git python2 --update-cache
+      install: sudo docker exec sharp sh -c "npm install --unsafe-perm"
+      script: sudo docker exec sharp sh -c "npm test"
+    - name: "Linux (musl) - Node 11"
+      os: linux
+      dist: trusty
+      sudo: true
+      language: minimal
+      before_install:
+        - sudo docker run -dit --name sharp --env CI --env PREBUILD_TOKEN --volume "${PWD}:/mnt/sharp" --workdir /mnt/sharp node:11-alpine
+        - sudo docker exec sharp apk add build-base git python2 --update-cache
+      install: sudo docker exec sharp sh -c "npm install --unsafe-perm"
+      script: sudo docker exec sharp sh -c "npm test"
+    - name: "OS X - Node 6"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "6"
+    - name: "OS X - Node 8"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "8"
+    - name: "OS X - Node 10"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "10"
+    - name: "OS X - Node 11"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "11"

CONTRIBUTING.md

@@ -0,0 +1,99 @@
+# Contributing to sharp
+
+Hello, thank you for your interest in helping!
+
+## Submit a new bug report
+
+Please create a [new issue](https://github.com/lovell/sharp/issues/new) containing the steps to reproduce the problem.
+
+If you're having installation problems, please include the output of running `npm install --verbose sharp`.
+
+New bugs are assigned a `triage` label whilst under investigation.
+
+## Submit a new feature request
+
+If a [similar request](https://github.com/lovell/sharp/labels/enhancement) exists, it's probably fastest to add a comment to it about your requirement.
+
+Implementation is usually straightforward if _libvips_ [already supports](https://libvips.github.io/libvips/API/current/) the feature you need.
+
+## Submit a Pull Request to fix a bug
+
+Thank you! To prevent the problem occurring again, please add unit tests that would have failed.
+
+Please select the `master` branch as the destination for your Pull Request so your fix can be included in the next minor release.
+
+Please squash your changes into a single commit using a command like `git rebase -i upstream/master`.
+
+To test C++ changes, you can compile the module using `npm install` and then run the tests using `npm test`.
+
+## Submit a Pull Request with a new feature
+
+Please add JavaScript [unit tests](https://github.com/lovell/sharp/tree/master/test/unit) to cover your new feature.
+A test coverage report for the JavaScript code is generated in the `coverage/lcov-report` directory.
+
+Where possible, the functional tests use gradient-based perceptual hashes
+based on [dHash](http://www.hackerfactor.com/blog/index.php?/archives/529-Kind-of-Like-That.html)
+to compare expected vs actual images.
+
+You deserve to add your details to the [list of contributors](https://github.com/lovell/sharp/blob/master/package.json#L5).
+
+Any change that modifies the existing public API should be added to the relevant work-in-progress branch for inclusion in the next major release.
+
+| Release | WIP branch |
+| ------: | :--------- |
+| v0.22.0 | uptake     |
+| v0.23.0 | vision     |
+
+Please squash your changes into a single commit using a command like `git rebase -i upstream/<wip-branch>`.
+
+### Add a new public method
+
+The API tries to be as fluent as possible. Image processing concepts follow the naming conventions from _libvips_ and, to a lesser extent, _ImageMagick_.
+
+Most methods have optional parameters and assume sensible defaults. Methods with mandatory parameters often have names like `doSomethingWith(X)`.
+
+Please ensure backwards compatibility where possible. Methods to modify previously default behaviour often have names like `withoutOptionY()` or `withExtraZ()`.
+
+Feel free to create a [new issue](https://github.com/lovell/sharp/issues/new) to gather feedback on a potential API change.
+
+### Remove an existing public method
+
+A method to be removed should be deprecated in the next major version then removed in the following major version.
+
+By way of example, the [bilinearInterpolation method](https://github.com/lovell/sharp/blob/v0.6.0/index.js#L155) present in v0.5.0 was deprecated in v0.6.0 and removed in v0.7.0.
+
+## Documentation
+
+The public API is documented with [JSDoc](http://usejsdoc.org/) annotated comments.
+
+These can be converted to Markdown by running:
+```sh
+npm run docs
+```
+
+Please include documentation updates in any Pull Request that modifies the public API.
+
+## Run the tests
+
+### Functional tests and static code analysis
+
+```sh
+npm test
+```
+
+### Memory leak tests
+
+Requires [Valgrind](http://valgrind.org/).
+
+```sh
+npm run test-leak
+```
+
+## Finally
+
+Please feel free to ask any questions via a
+[new issue](https://github.com/lovell/sharp/issues/new).
+
+If you're unable to post details publicly, please
+[e-mail](https://github.com/lovell/sharp/blob/master/package.json#L4)
+for private, paid consulting.

README.md

@@ -1,608 +1,112 @@
 # sharp
 
-* [Installation](https://github.com/lovell/sharp#installation)
-* [Usage examples](https://github.com/lovell/sharp#usage-examples)
-* [API](https://github.com/lovell/sharp#api)
-* [Testing](https://github.com/lovell/sharp#testing)
-* [Performance](https://github.com/lovell/sharp#performance)
-* [Thanks](https://github.com/lovell/sharp#thanks)
-* [Licence](https://github.com/lovell/sharp#licence)
+<img src="https://raw.githubusercontent.com/lovell/sharp/master/docs/image/sharp-logo.svg?sanitize=true" width="160" height="160" alt="sharp logo" align="right">
 
-The typical use case for this high speed Node.js module is to convert large images of many formats to smaller, web-friendly JPEG, PNG and WebP images of varying dimensions.
-
-The performance of JPEG resizing is typically 8x faster than ImageMagick and GraphicsMagick, based mainly on the number of CPU cores available.
-
-Memory usage is kept to a minimum, no child processes are spawned, everything remains non-blocking thanks to _libuv_ and Promises/A+ are supported.
-
-This module supports reading and writing JPEG, PNG and WebP images to and from Streams, Buffer objects and the filesystem. It also supports reading images of many other types from the filesystem via libmagick++ or libgraphicsmagick++ if present.
-
-When generating JPEG output all metadata is removed and Huffman tables optimised without having to use separate command line tools like [jpegoptim](https://github.com/tjko/jpegoptim) and [jpegtran](http://jpegclub.org/jpegtran/).
-
-Anyone who has used the Node.js bindings for [GraphicsMagick](https://github.com/aheckmann/gm) will find the API similarly fluent.
-
-This module is powered by the blazingly fast [libvips](https://github.com/jcupitt/libvips) image processing library, originally created in 1989 at Birkbeck College and currently maintained by [John Cupitt](https://github.com/jcupitt).
-
-## Installation
-
-	npm install sharp
-
-### Prerequisites
-
-* Node.js v0.10+
-* [libvips](https://github.com/jcupitt/libvips) v7.40.0+ (7.42.0+ recommended)
-
-To install the most suitable version of libvips on the following Operating Systems:
-
-* Mac OS
-  * Homebrew
-  * MacPorts
-* Debian Linux
-  * Debian 7, 8
-  * Ubuntu 12.04, 14.04, 14.10, 15.04
-  * Mint 13, 17
-* Red Hat Linux
-  * RHEL/Centos/Scientific 6, 7
-  * Fedora 21, 22
-
-run the following as a user with `sudo` access:
-
-	curl -s https://raw.githubusercontent.com/lovell/sharp/master/preinstall.sh | sudo bash -
-
-or run the following as `root`:
-
-	curl -s https://raw.githubusercontent.com/lovell/sharp/master/preinstall.sh | bash -
-
-The [preinstall.sh](https://github.com/lovell/sharp/blob/master/preinstall.sh) script requires `curl` and `pkg-config`.
-
-### Mac OS tips
-
-Manual install via homebrew:
-
-	brew install homebrew/science/vips --with-webp --with-graphicsmagick
-
-A missing or incorrectly configured _Xcode Command Line Tools_ installation [can lead](https://github.com/lovell/sharp/issues/80) to a `library not found for -ljpeg` error. If so, please try:
-
-	xcode-select --install
-
-The _gettext_ dependency of _libvips_ [can lead](https://github.com/lovell/sharp/issues/9) to a `library not found for -lintl` error. If so, please try:
-
-	brew link gettext --force
-
-### Install libvips on Heroku
-
-[Alessandro Tagliapietra](https://github.com/alex88) maintains an [Heroku buildpack for libvips](https://github.com/alex88/heroku-buildpack-vips) and its dependencies.
-
-### Using with gulp.js
-
-[Eugeny Vlasenko](https://github.com/mahnunchik) maintains [gulp-responsive](https://www.npmjs.org/package/gulp-responsive) and [Mohammad Prabowo](https://github.com/rizalp) maintains [gulp-sharp](https://www.npmjs.org/package/gulp-sharp).
-
-## Usage examples
-
-```javascript
-var sharp = require('sharp');
+```sh
+npm install sharp
 ```
 
-```javascript
-sharp('input.jpg').resize(300, 200).toFile('output.jpg', function(err) {
-  if (err) {
-    throw err;
-  }
-  // output.jpg is a 300 pixels wide and 200 pixels high image
-  // containing a scaled and cropped version of input.jpg
-});
-```
+The typical use case for this high speed Node.js module
+is to convert large images in common formats to
+smaller, web-friendly JPEG, PNG and WebP images of varying dimensions.
+
+Resizing an image is typically 4x-5x faster than using the
+quickest ImageMagick and GraphicsMagick settings.
+
+Colour spaces, embedded ICC profiles and alpha transparency channels are all handled correctly.
+Lanczos resampling ensures quality is not sacrificed for speed.
+
+As well as image resizing, operations such as
+rotation, extraction, compositing and gamma correction are available.
+
+Most modern 64-bit OS X, Windows and Linux systems running
+Node versions 6, 8, 10 and 11
+do not require any additional install or runtime dependencies.
+
+## Examples
 
 ```javascript
-var transformer = sharp().resize(300, 200).crop(sharp.gravity.north);
-readableStream.pipe(transformer).pipe(writableStream);
-// Read image data from readableStream, resize and write image data to writableStream
+const sharp = require('sharp');
 ```
 
-```javascript
-var image = sharp(inputJpg);
-image.metadata(function(err, metadata) {
-  image.resize(metadata.width / 2).webp().toBuffer(function(err, outputBuffer, info) {
-    // outputBuffer contains a WebP image half the width and height of the original JPEG
-  });
-});
-```
+### Callback
 
 ```javascript
-var pipeline = sharp()
+sharp(inputBuffer)
+  .resize(320, 240)
+  .toFile('output.webp', (err, info) => { ... });
+```
+
+### Promise
+
+```javascript
+sharp('input.jpg')
   .rotate()
-  .resize(null, 200)
-  .progressive()
-  .toBuffer(function(err, outputBuffer, info) {
-    if (err) {
-      throw err;
-    }
-    // outputBuffer contains 200px high progressive JPEG image data,
-    // auto-rotated using EXIF Orientation tag
-    // info.width and info.height contain the dimensions of the resized image
-  });
-readableStream.pipe(pipeline);
-```
-
-```javascript
-sharp('input.png')
-  .rotate(180)
-  .resize(300)
-  .flatten()
-  .background('#ff6600')
-  .sharpen()
-  .withMetadata()
-  .quality(90)
-  .webp()
+  .resize(200)
   .toBuffer()
-  .then(function(outputBuffer) {
-    // outputBuffer contains upside down, 300px wide, alpha channel flattened
-    // onto orange background, sharpened, with metadata, 90% quality WebP image
-    // data
-  });
+  .then( data => { ... })
+  .catch( err => { ... });
 ```
 
+### Async/await
+
 ```javascript
-http.createServer(function(request, response) {
-  response.writeHead(200, {'Content-Type': 'image/webp'});
-  sharp('input.jpg').rotate().resize(200).webp().pipe(response);
-}).listen(8000);
-// Create HTTP server that always returns auto-rotated 'input.jpg',
-// resized to 200 pixels wide, in WebP format
+const semiTransparentRedPng = await sharp({
+  create: {
+    width: 48,
+    height: 48,
+    channels: 4,
+    background: { r: 255, g: 0, b: 0, alpha: 0.5 }
+  }
+})
+  .png()
+  .toBuffer();
 ```
 
+### Stream
+
 ```javascript
-sharp(input)
-  .extract(top, left, width, height)
-  .toFile(output);
-  // Extract a region of the input image, saving in the same format.
+const roundedCorners = Buffer.from(
+  '<svg><rect x="0" y="0" width="200" height="200" rx="50" ry="50"/></svg>'
+);
+
+const roundedCornerResizer =
+  sharp()
+    .resize(200, 200)
+    .composite([{
+      input: roundedCorners,
+      blend: 'dest-in'
+    }])
+    .png();
+
+readableStream
+  .pipe(roundedCornerResizer)
+  .pipe(writableStream);
 ```
 
-```javascript
-sharp(input)
-  .extract(topOffsetPre, leftOffsetPre, widthPre, heightPre)
-  .resize(width, height)
-  .extract(topOffsetPost, leftOffsetPost, widthPost, heightPost)
-  .toFile(output);
-  // Extract a region, resize, then extract from the resized image
-```
+[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.svg?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
 
-```javascript
-sharp(inputBuffer)
-  .resize(200, 300)
-  .interpolateWith(sharp.interpolator.nohalo)
-  .background('white')
-  .embed()
-  .toFile('output.tiff')
-  .then(function() {
-    // output.tiff is a 200 pixels wide and 300 pixels high image
-    // containing a bicubic scaled version, embedded on a white canvas,
-    // of the image data in inputBuffer
-  });
-```
+### Documentation
 
-```javascript
-sharp('input.gif')
-  .resize(200, 300)
-  .background({r: 0, g: 0, b: 0, a: 0})
-  .embed()
-  .webp()
-  .toBuffer(function(err, outputBuffer) {
-    if (err) {
-      throw err;
-    }
-    // outputBuffer contains WebP image data of a 200 pixels wide and 300 pixels high
-    // containing a scaled version, embedded on a transparent canvas, of input.gif
-  });
-```
+Visit [sharp.pixelplumbing.com](https://sharp.pixelplumbing.com/) for complete
+[installation instructions](https://sharp.pixelplumbing.com/page/install),
+[API documentation](https://sharp.pixelplumbing.com/page/api),
+[benchmark tests](https://sharp.pixelplumbing.com/page/performance) and
+[changelog](https://sharp.pixelplumbing.com/page/changelog).
 
-```javascript
-sharp(inputBuffer)
-  .resize(200, 200)
-  .max()
-  .jpeg()
-  .toBuffer().then(function(outputBuffer) {
-    // outputBuffer contains JPEG image data no wider than 200 pixels and no higher
-    // than 200 pixels regardless of the inputBuffer image dimensions
-  });
-```
+### Contributing
 
-## API
+A [guide for contributors](https://github.com/lovell/sharp/blob/master/CONTRIBUTING.md)
+covers reporting bugs, requesting features and submitting code changes.
 
-### Input methods
+### Licensing
 
-#### sharp([input])
-
-Constructor to which further methods are chained. `input`, if present, can be one of:
-
-* Buffer containing JPEG, PNG, WebP or TIFF image data, or
-* String containing the filename of an image, with most major formats supported.
-
-The object returned implements the [stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
-
-JPEG, PNG, WebP or TIFF format image data can be streamed into the object when `input` is not provided.
-
-JPEG, PNG or WebP format image data can be streamed out from this object.
-
-#### metadata([callback])
-
-Fast access to image metadata without decoding any compressed image data.
-
-`callback`, if present, gets the arguments `(err, metadata)` where `metadata` has the attributes:
-
-* `format`: Name of decoder to be used to decompress image data e.g. `jpeg`, `png`, `webp` (for file-based input additionally `tiff` and `magick`)
-* `width`: Number of pixels wide
-* `height`: Number of pixels high
-* `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `scrgb`, `cmyk`, `lab`, `xyz`, `b-w` [...](https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L522)
-* `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
-* `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
-* `orientation`: Number value of the EXIF Orientation header, if present
-
-A Promises/A+ promise is returned when `callback` is not provided.
-
-#### sequentialRead()
-
-An advanced setting that switches the libvips access method to `VIPS_ACCESS_SEQUENTIAL`. This will reduce memory usage and can improve performance on some systems.
-
-### Image transformation options
-
-#### resize(width, [height])
-
-Scale output to `width` x `height`. By default, the resized image is cropped to the exact size specified.
-
-`width` is the Number of pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
-
-`height` is the Number of pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
-
-#### extract(top, left, width, height)
-
-Extract a region of the image. Can be used with or without a `resize` operation.
-
-`top` and `left` are the offset, in pixels, from the top-left corner.
-
-`width` and `height` are the dimensions of the extracted image.
-
-Use `extract` before `resize` for pre-resize extraction. Use `extract` after `resize` for post-resize extraction. Use `extract` before and after for both.
-
-#### crop([gravity])
-
-Crop the resized image to the exact size specified, the default behaviour.
-
-`gravity`, if present, is an attribute of the `sharp.gravity` Object e.g. `sharp.gravity.north`.
-
-Possible values are `north`, `east`, `south`, `west`, `center` and `centre`. The default gravity is `center`/`centre`.
-
-#### max()
-
-Preserving aspect ratio, resize the image to the maximum `width` or `height` specified.
-
-Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
-
-#### background(rgba)
-
-Set the background for the `embed` and `flatten` operations.
-
-`rgba` is parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
-
-The alpha value is a float between `0` (transparent) and `1` (opaque).
-
-The default background is `{r: 0, g: 0, b: 0, a: 1}`, black without transparency.
-
-#### embed()
-
-Preserving aspect ratio, resize the image to the maximum `width` or `height` specified then embed on a background of the exact `width` and `height` specified.
-
-If the background contains an alpha value then WebP and PNG format output images will contain an alpha channel, even when the input image does not.
-
-#### flatten()
-
-Merge alpha transparency channel, if any, with `background`.
-
-#### rotate([angle])
-
-Rotate the output image by either an explicit angle or auto-orient based on the EXIF `Orientation` tag.
-
-`angle`, if present, is a Number with a value of `0`, `90`, `180` or `270`.
-
-Use this method without `angle` to determine the angle from EXIF data. Mirroring is supported and may infer the use of a `flip` operation.
-
-#### flip()
-
-Flip the image about the vertical Y axis. This always occurs after rotation, if any.
-
-#### flop()
-
-Flop the image about the horizontal X axis. This always occurs after rotation, if any.
-
-#### withoutEnlargement()
-
-Do not enlarge the output image if the input image width *or* height are already less than the required dimensions.
-
-This is equivalent to GraphicsMagick's `>` geometry option: "change the dimensions of the image only if its width or height exceeds the geometry specification".
-
-#### blur([radius])
-
-When used without parameters, performs a fast, mild blur of the output image. This typically reduces performance by 10%.
-
-When a `radius` is provided, performs a slower, more accurate Gaussian blur. This typically reduces performance by 30%.
-
-* `radius`, if present, is an integral Number representing the approximate blur mask radius in pixels.
-
-#### sharpen([radius], [flat], [jagged])
-
-When used without parameters, performs a fast, mild sharpen of the output image. This typically reduces performance by 10%.
-
-When a `radius` is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space. Separate control over the level of sharpening in "flat" and "jagged" areas is available. This typically reduces performance by 50%.
-
-* `radius`, if present, is an integral Number representing the sharpen mask radius in pixels.
-* `flat`, if present, is a Number representing the level of sharpening to apply to "flat" areas, defaulting to a value of 1.0.
-* `jagged`, if present, is a Number representing the level of sharpening to apply to "jagged" areas, defaulting to a value of 2.0.
-
-#### interpolateWith(interpolator)
-
-Use the given interpolator for image resizing, where `interpolator` is an attribute of the `sharp.interpolator` Object e.g. `sharp.interpolator.bicubic`.
-
-Possible interpolators, in order of performance, are:
-
-* `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation), suitable for image enlargement only.
-* `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), the default and fastest image reduction interpolation.
-* `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation), which typically reduces performance by 5%.
-* `vertexSplitQuadraticBasisSpline`: Use [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48), which prevents "staircasing" and typically reduces performance by 5%.
-* `locallyBoundedBicubic`: Use [LBB interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/lbb.cpp#L100), which prevents some "[acutance](http://en.wikipedia.org/wiki/Acutance)" and typically reduces performance by a factor of 2.
-* `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance and typically reduces performance by a factor of 3.
-
-#### gamma([gamma])
-
-Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of `1/gamma` then increasing the encoding (brighten) post-resize at a factor of `gamma`.
-
-`gamma`, if present, is a Number betweem 1 and 3. The default value is `2.2`, a suitable approximation for sRGB images.
-
-This can improve the perceived brightness of a resized image in non-linear colour spaces.
-
-JPEG input images will not take advantage of the shrink-on-load performance optimisation when applying a gamma correction.
-
-#### grayscale() / greyscale()
-
-Convert to 8-bit greyscale; 256 shades of grey.
-
-This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use `gamma()` with `greyscale()` for the best results.
-
-The output image will still be web-friendly sRGB and contain three (identical) channels.
-
-### Output options
-
-#### jpeg()
-
-Use JPEG format for the output image.
-
-#### png()
-
-Use PNG format for the output image.
-
-#### webp()
-
-Use WebP format for the output image.
-
-#### quality(quality)
-
-The output quality to use for lossy JPEG, WebP and TIFF output formats. The default quality is `80`.
-
-`quality` is a Number between 1 and 100.
-
-#### progressive()
-
-Use progressive (interlace) scan for JPEG and PNG output. This typically reduces compression performance by 30% but results in an image that can be rendered sooner when decompressed.
-
-#### withMetadata()
-
-Include all metadata (ICC, EXIF, XMP) from the input image in the output image. The default behaviour is to strip all metadata.
-
-#### compressionLevel(compressionLevel)
-
-An advanced setting for the _zlib_ compression level of the lossless PNG output format. The default level is `6`.
-
-`compressionLevel` is a Number between 0 and 9.
-
-#### withoutAdaptiveFiltering()
-
-_Requires libvips 7.41.0+_
-
-An advanced and experimental PNG output setting to disable adaptive row filtering.
-
-### Output methods
-
-#### toFile(filename, [callback])
-
-`filename` is a String containing the filename to write the image data to. The format is inferred from the extension, with JPEG, PNG, WebP and TIFF supported.
-
-`callback`, if present, is called with two arguments `(err, info)` where:
-
-* `err` contains an error message, if any.
-* `info` contains the output image `format`, `width` and `height`.
-
-A Promises/A+ promise is returned when `callback` is not provided.
-
-#### toBuffer([callback])
-
-Write image data to a Buffer, the format of which will match the input image by default. JPEG, PNG and WebP are supported.
-
-`callback`, if present, gets three arguments `(err, buffer, info)` where:
-
-* `err` is an error message, if any.
-* `buffer` is the output image data.
-* `info` contains the output image `format`, `width` and `height`.
-
-A Promises/A+ promise is returned when `callback` is not provided.
-
-### Utility methods
-
-#### sharp.cache([memory], [items])
-
-If `memory` or `items` are provided, set the limits of _libvips'_ operation cache.
-
-* `memory` is the maximum memory in MB to use for this cache, with a default value of 100
-* `items` is the maximum number of operations to cache, with a default value of 500
-
-This method always returns cache statistics, useful for determining how much working memory is required for a particular task.
-
-```javascript
-var stats = sharp.cache(); // { current: 75, high: 99, memory: 100, items: 500 }
-sharp.cache(200); // { current: 75, high: 99, memory: 200, items: 500 }
-sharp.cache(50, 200); // { current: 49, high: 99, memory: 50, items: 200}
-```
-
-#### sharp.concurrency([threads])
-
-`threads`, if provided, is the Number of threads _libvips'_ should create for image processing. The default value is the number of CPU cores. A value of `0` will reset to this default.
-
-This method always returns the current concurrency.
-
-```javascript
-var threads = sharp.concurrency(); // 4
-sharp.concurrency(2); // 2
-sharp.concurrency(0); // 4
-```
-
-#### sharp.counters()
-
-Provides access to internal task counters.
-
-* `queue` is the number of tasks this module has queued waiting for _libuv_ to provide a worker thread from its pool.
-* `process` is the number of resize tasks currently being processed.
-
-```javascript
-var counters = sharp.counters(); // { queue: 2, process: 4 }
-```
-
-## Testing
-
-### Functional tests
-
-#### Coverage
-
-[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.png?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
-
-#### Ubuntu 12.04
-
-[![Ubuntu 12.04 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
-
-#### Centos 6.5
-
-[![Centos 6.5 Build Status](https://snap-ci.com/lovell/sharp/branch/master/build_image)](https://snap-ci.com/lovell/sharp/branch/master)
-
-#### It worked on my machine
-
-```
-npm test
-```
-
-### Memory leak tests
-
-```
-cd sharp/test/leak
-./leak.sh
-```
-
-Requires _valgrind_:
-
-```
-brew install valgrind
-```
-
-```
-sudo apt-get install -qq valgrind
-```
-
-### Benchmark tests
-
-```
-cd sharp/test/bench
-npm install
-npm test
-```
-
-Requires both _ImageMagick_ and _GraphicsMagick_:
-
-```
-brew install imagemagick
-brew install graphicsmagick
-```
-
-```
-sudo apt-get install -qq imagemagick graphicsmagick libmagick++-dev
-```
-
-```
-sudo yum install ImageMagick
-sudo yum install -y http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
-sudo yum install -y --enablerepo=epel GraphicsMagick
-```
-
-## Performance
-
-### Test environment
-
-* AWS EC2 [c3.xlarge](http://aws.amazon.com/ec2/instance-types/#Compute_Optimized)
-* Ubuntu 14.04
-* libvips 7.40.8
-* liborc 0.4.22
-
-### The contenders
-
-* [imagemagick-native](https://github.com/mash/node-imagemagick-native) v1.2.2 - Supports Buffers only and blocks main V8 thread whilst processing.
-* [imagemagick](https://github.com/yourdeveloper/node-imagemagick) v0.1.3 - Supports filesystem only and "has been unmaintained for a long time".
-* [gm](https://github.com/aheckmann/gm) v1.16.0 - Fully featured wrapper around GraphicsMagick.
-* sharp v0.6.2 - Caching within libvips disabled to ensure a fair comparison.
-
-### The task
-
-Decompress a 2725x2225 JPEG image, resize and crop to 720x480, then compress to JPEG.
-
-### Results
-
-| Module                | Input  | Output | Ops/sec | Speed-up |
-| :-------------------- | :----- | :----- | ------: | -------: |
-| imagemagick-native    | buffer | buffer |    1.58 |        1 |
-| imagemagick           | file   | file   |    6.23 |      3.9 |
-| gm                    | buffer | file   |    5.32 |      3.4 |
-| gm                    | buffer | buffer |    5.32 |      3.4 |
-| gm                    | file   | file   |    5.36 |      3.4 |
-| gm                    | file   | buffer |    5.36 |      3.4 |
-| sharp                 | buffer | file   |   22.05 |     14.0 |
-| sharp                 | buffer | buffer |   22.14 |     14.0 |
-| sharp                 | file   | file   |   21.79 |     13.8 |
-| sharp                 | file   | buffer |   21.90 |     13.9 |
-| sharp                 | stream | stream |   20.87 |     13.2 |
-| sharp +promise        | file   | buffer |   21.89 |     13.9 |
-| sharp +sharpen        | file   | buffer |   19.69 |     12.5 |
-| sharp +progressive    | file   | buffer |   16.93 |     10.7 |
-| sharp +sequentialRead | file   | buffer |   21.60 |     13.7 |
-
-You can expect greater performance with caching enabled (default) and using 8+ core machines.
-
-## Thanks
-
-This module would never have been possible without the help and code contributions of the following people:
-
-* [John Cupitt](https://github.com/jcupitt)
-* [Pierre Inglebert](https://github.com/pierreinglebert)
-* [Jonathan Ong](https://github.com/jonathanong)
-* [Chanon Sajjamanochai](https://github.com/chanon)
-* [Juliano Julio](https://github.com/julianojulio)
-* [Daniel Gasienica](https://github.com/gasi)
-* [Julian Walker](https://github.com/julianwa)
-* [Amit Pitaru](https://github.com/apitaru)
-* [Brandon Aaron](https://github.com/brandonaaron)
-* [Andreas Lind](https://github.com/papandreou)
-
-Thank you!
-
-## Licence
-
-Copyright 2013, 2014 Lovell Fuller and contributors.
+Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
-You may obtain a copy of the License at [http://www.apache.org/licenses/LICENSE-2.0](http://www.apache.org/licenses/LICENSE-2.0.html)
+You may obtain a copy of the License at
+[https://www.apache.org/licenses/LICENSE-2.0](https://www.apache.org/licenses/LICENSE-2.0)
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,

appveyor.yml

@@ -0,0 +1,16 @@
+os: Visual Studio 2015
+version: "{build}"
+build: off
+platform: x64
+environment:
+  matrix:
+  - nodejs_version: "6"
+  - nodejs_version: "8"
+  - nodejs_version: "10"
+  - nodejs_version: "11"
+install:
+  - ps: Install-Product node $env:nodejs_version x64
+  - npm install -g npm@5
+  - npm install
+test_script:
+  - npm test

binding.gyp

@@ -1,23 +1,167 @@
 {
   'targets': [{
+    'target_name': 'libvips-cpp',
+    'conditions': [
+      ['OS == "win"', {
+        # Build libvips C++ binding for Windows due to MSVC std library ABI changes
+        'type': 'shared_library',
+        'defines': [
+          'VIPS_CPLUSPLUS_EXPORTS',
+          '_ALLOW_KEYWORD_MACROS'
+        ],
+        'sources': [
+          'src/libvips/cplusplus/VError.cpp',
+          'src/libvips/cplusplus/VInterpolate.cpp',
+          'src/libvips/cplusplus/VImage.cpp'
+        ],
+        'include_dirs': [
+          'vendor/include',
+          'vendor/include/glib-2.0',
+          'vendor/lib/glib-2.0/include'
+        ],
+        'libraries': [
+          '../vendor/lib/libvips.lib',
+          '../vendor/lib/libglib-2.0.lib',
+          '../vendor/lib/libgobject-2.0.lib'
+        ],
+        'configurations': {
+          'Release': {
+            'msvs_settings': {
+              'VCCLCompilerTool': {
+                'ExceptionHandling': 1
+              }
+            },
+            'msvs_disabled_warnings': [
+              4275
+            ]
+          }
+        }
+      }, {
+        # Ignore this target for non-Windows
+        'type': 'none'
+      }]
+    ]
+  }, {
     'target_name': 'sharp',
-    'sources': [
-      'src/common.cc',
-      'src/utilities.cc',
-      'src/metadata.cc',
-      'src/resize.cc',
-      'src/sharp.cc'
+    'dependencies': [
+      'libvips-cpp'
     ],
     'variables': {
-      'PKG_CONFIG_PATH': '<!(which brew >/dev/null 2>&1 && eval $(brew --env) && echo $PKG_CONFIG_LIBDIR || true):$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig:/usr/lib/pkgconfig'
+      'runtime_link%': 'shared',
+      'conditions': [
+        ['OS != "win"', {
+          'pkg_config_path': '<!(node -e "console.log(require(\'./lib/libvips\').pkgConfigPath())")',
+          'use_global_libvips': '<!(node -e "console.log(Boolean(require(\'./lib/libvips\').useGlobalLibvips()).toString())")'
+        }, {
+          'pkg_config_path': '',
+          'use_global_libvips': ''
+        }]
+      ]
     },
-    'libraries': [
-      '<!(PKG_CONFIG_PATH="<(PKG_CONFIG_PATH)" pkg-config --libs vips)'
+    'sources': [
+      'src/common.cc',
+      'src/metadata.cc',
+      'src/stats.cc',
+      'src/operations.cc',
+      'src/pipeline.cc',
+      'src/sharp.cc',
+      'src/utilities.cc'
     ],
     'include_dirs': [
-      '<!(PKG_CONFIG_PATH="<(PKG_CONFIG_PATH)" pkg-config --cflags vips glib-2.0)',
       '<!(node -e "require(\'nan\')")'
     ],
+    'conditions': [
+      ['use_global_libvips == "true"', {
+        # Use pkg-config for include and lib
+        'include_dirs': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --cflags-only-I vips-cpp vips glib-2.0 | sed s\/-I//g)'],
+        'conditions': [
+          ['runtime_link == "static"', {
+            'libraries': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --libs --static vips-cpp)']
+          }, {
+            'libraries': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --libs vips-cpp)']
+          }],
+          ['OS == "linux"', {
+            'defines': [
+              # Inspect libvips-cpp.so to determine which C++11 ABI version was used and set _GLIBCXX_USE_CXX11_ABI accordingly. This is quite horrible.
+              '_GLIBCXX_USE_CXX11_ABI=<!(if readelf -Ws "$(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --variable libdir vips-cpp)/libvips-cpp.so" | c++filt | grep -qF __cxx11;then echo "1";else echo "0";fi)'
+            ]
+          }]
+        ]
+      }, {
+        # Use pre-built libvips stored locally within node_modules
+        'include_dirs': [
+          'vendor/include',
+          'vendor/include/glib-2.0',
+          'vendor/lib/glib-2.0/include'
+        ],
+        'conditions': [
+          ['OS == "win"', {
+            'defines': [
+              '_ALLOW_KEYWORD_MACROS'
+            ],
+            'libraries': [
+              '../vendor/lib/libvips.lib',
+              '../vendor/lib/libglib-2.0.lib',
+              '../vendor/lib/libgobject-2.0.lib'
+            ]
+          }],
+          ['OS == "mac"', {
+            'libraries': [
+              '../vendor/lib/libvips-cpp.42.dylib',
+              '../vendor/lib/libvips.42.dylib',
+              '../vendor/lib/libglib-2.0.0.dylib',
+              '../vendor/lib/libgobject-2.0.0.dylib',
+              # Ensure runtime linking is relative to sharp.node
+              '-rpath \'@loader_path/../../vendor/lib\''
+            ]
+          }],
+          ['OS == "linux"', {
+            'defines': [
+              '_GLIBCXX_USE_CXX11_ABI=0'
+            ],
+            'libraries': [
+              '../vendor/lib/libvips-cpp.so',
+              '../vendor/lib/libvips.so',
+              '../vendor/lib/libglib-2.0.so',
+              '../vendor/lib/libgobject-2.0.so',
+              # Dependencies of dependencies, included for openSUSE support
+              '../vendor/lib/libcairo.so',
+              '../vendor/lib/libcroco-0.6.so',
+              '../vendor/lib/libexif.so',
+              '../vendor/lib/libexpat.so',
+              '../vendor/lib/libffi.so',
+              '../vendor/lib/libfontconfig.so',
+              '../vendor/lib/libfreetype.so',
+              '../vendor/lib/libfribidi.so',
+              '../vendor/lib/libgdk_pixbuf-2.0.so',
+              '../vendor/lib/libgif.so',
+              '../vendor/lib/libgio-2.0.so',
+              '../vendor/lib/libgmodule-2.0.so',
+              '../vendor/lib/libgsf-1.so',
+              '../vendor/lib/libgthread-2.0.so',
+              '../vendor/lib/libharfbuzz.so',
+              '../vendor/lib/libjpeg.so',
+              '../vendor/lib/liblcms2.so',
+              '../vendor/lib/liborc-0.4.so',
+              '../vendor/lib/libpango-1.0.so',
+              '../vendor/lib/libpangocairo-1.0.so',
+              '../vendor/lib/libpangoft2-1.0.so',
+              '../vendor/lib/libpixman-1.so',
+              '../vendor/lib/libpng.so',
+              '../vendor/lib/librsvg-2.so',
+              '../vendor/lib/libtiff.so',
+              '../vendor/lib/libwebp.so',
+              '../vendor/lib/libwebpdemux.so',
+              '../vendor/lib/libwebpmux.so',
+              '../vendor/lib/libxml2.so',
+              '../vendor/lib/libz.so',
+              # Ensure runtime linking is relative to sharp.node
+              '-Wl,--disable-new-dtags -Wl,-rpath=\'$${ORIGIN}/../../vendor/lib\''
+            ]
+          }]
+        ]
+      }]
+    ],
     'cflags_cc': [
       '-std=c++0x',
       '-fexceptions',
@@ -25,14 +169,38 @@
       '-O3'
     ],
     'xcode_settings': {
+      'CLANG_CXX_LANGUAGE_STANDARD': 'c++11',
+      'CLANG_CXX_LIBRARY': 'libc++',
+      'MACOSX_DEPLOYMENT_TARGET': '10.7',
+      'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
+      'GCC_ENABLE_CPP_RTTI': 'YES',
       'OTHER_CPLUSPLUSFLAGS': [
-        '-std=c++11',
-        '-stdlib=libc++',
         '-fexceptions',
         '-Wall',
         '-O3'
-      ],
-      'MACOSX_DEPLOYMENT_TARGET': '10.7'
-    }
+      ]
+    },
+    'configurations': {
+      'Release': {
+        'cflags_cc': [
+          '-Wno-cast-function-type',
+          '-Wno-deprecated-declarations'
+        ],
+        'xcode_settings': {
+          'OTHER_CPLUSPLUSFLAGS': [
+            '-Wno-deprecated-declarations'
+          ]
+        },
+        'msvs_settings': {
+          'VCCLCompilerTool': {
+            'ExceptionHandling': 1
+          }
+        },
+        'msvs_disabled_warnings': [
+          4275,
+          4996
+        ]
+      }
+    },
   }]
 }

docs/api-channel.md

@@ -0,0 +1,115 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## removeAlpha
+
+Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
+
+### Examples
+
+```javascript
+sharp('rgba.png')
+  .removeAlpha()
+  .toFile('rgb.png', function(err, info) {
+    // rgb.png is a 3 channel image without an alpha channel
+  });
+```
+
+Returns **Sharp** 
+
+## ensureAlpha
+
+Ensure alpha channel, if missing. The added alpha channel will be fully opaque. This is a no-op if the image already has an alpha channel.
+
+### Examples
+
+```javascript
+sharp('rgb.jpg')
+  .ensureAlpha()
+  .toFile('rgba.png', function(err, info) {
+    // rgba.png is a 4 channel image with a fully opaque alpha channel
+  });
+```
+
+Returns **Sharp** 
+
+## extractChannel
+
+Extract a single channel from a multi-channel image.
+
+### Parameters
+
+-   `channel` **([Number][1] \| [String][2])** zero-indexed band number to extract, or `red`, `green` or `blue` as alternative to `0`, `1` or `2` respectively.
+
+### Examples
+
+```javascript
+sharp(input)
+  .extractChannel('green')
+  .toFile('input_green.jpg', function(err, info) {
+    // info.channels === 1
+    // input_green.jpg contains the green channel of the input image
+   });
+```
+
+-   Throws **[Error][3]** Invalid channel
+
+Returns **Sharp** 
+
+## joinChannel
+
+Join one or more channels to the image.
+The meaning of the added channels depends on the output colourspace, set with `toColourspace()`.
+By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+Channel ordering follows vips convention:
+
+-   sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha.
+-   CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha.
+
+Buffers may be any of the image formats supported by sharp: JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data.
+For raw pixel input, the `options` object should contain a `raw` attribute, which follows the format of the attribute of the same name in the `sharp()` constructor.
+
+### Parameters
+
+-   `images` **([Array][4]&lt;([String][2] \| [Buffer][5])> | [String][2] \| [Buffer][5])** one or more images (file paths, Buffers).
+-   `options` **[Object][6]** image options, see `sharp()` constructor.
+
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+## bandbool
+
+Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.
+
+### Parameters
+
+-   `boolOp` **[String][2]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+
+### Examples
+
+```javascript
+sharp('3-channel-rgb-input.png')
+  .bandbool(sharp.bool.and)
+  .toFile('1-channel-output.png', function (err, info) {
+    // The output will be a single channel image where each pixel `P = R & G & B`.
+    // If `I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111]`
+    // then `O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2`.
+  });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[5]: https://nodejs.org/api/buffer.html
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

docs/api-colour.md

@@ -0,0 +1,79 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## tint
+
+Tint the image using the provided chroma while preserving the image luminance.
+An alpha channel may be present and will be unchanged by the operation.
+
+### Parameters
+
+-   `rgb` **([String][1] \| [Object][2])** parsed by the [color][3] module to extract chroma values.
+
+
+-   Throws **[Error][4]** Invalid parameter
+
+Returns **Sharp** 
+
+## greyscale
+
+Convert to 8-bit greyscale; 256 shades of grey.
+This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use `gamma()` with `greyscale()` for the best results.
+By default the output image will be web-friendly sRGB and contain three (identical) color channels.
+This may be overridden by other sharp operations such as `toColourspace('b-w')`,
+which will produce an output image containing one color channel.
+An alpha channel may be present, and will be unchanged by the operation.
+
+### Parameters
+
+-   `greyscale` **[Boolean][5]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## grayscale
+
+Alternative spelling of `greyscale`.
+
+### Parameters
+
+-   `grayscale` **[Boolean][5]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## toColourspace
+
+Set the output colourspace.
+By default output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+
+### Parameters
+
+-   `colourspace` **[String][1]?** output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][6]
+
+
+-   Throws **[Error][4]** Invalid parameters
+
+Returns **Sharp** 
+
+## toColorspace
+
+Alternative spelling of `toColourspace`.
+
+### Parameters
+
+-   `colorspace` **[String][1]?** output colorspace.
+
+
+-   Throws **[Error][4]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[3]: https://www.npmjs.org/package/color
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[6]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568

docs/api-composite.md

@@ -0,0 +1,81 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## composite
+
+Composite image(s) over the processed (resized, extracted etc.) image.
+
+The images to composite must be the same size or smaller than the processed image.
+If both `top` and `left` options are provided, they take precedence over `gravity`.
+
+The `blend` option can be one of `clear`, `source`, `over`, `in`, `out`, `atop`,
+`dest`, `dest-over`, `dest-in`, `dest-out`, `dest-atop`,
+`xor`, `add`, `saturate`, `multiply`, `screen`, `overlay`, `darken`, `lighten`,
+`colour-dodge`, `color-dodge`, `colour-burn`,`color-burn`,
+`hard-light`, `soft-light`, `difference`, `exclusion`.
+
+More information about blend modes can be found at
+[https://libvips.github.io/libvips/API/current/libvips-conversion.html#VipsBlendMode][1]
+and [https://www.cairographics.org/operators/][2]
+
+### Parameters
+
+-   `images` **[Array][3]&lt;[Object][4]>** Ordered list of images to composite
+    -   `images[].input` **([Buffer][5] \| [String][6])?** Buffer containing image data or String containing the path to an image file.
+    -   `images[].blend` **[String][6]** how to blend this image with the image below. (optional, default `'over'`)
+    -   `images[].gravity` **[String][6]** gravity at which to place the overlay. (optional, default `'centre'`)
+    -   `images[].top` **[Number][7]?** the pixel offset from the top edge.
+    -   `images[].left` **[Number][7]?** the pixel offset from the left edge.
+    -   `images[].tile` **[Boolean][8]** set to true to repeat the overlay image across the entire image with the given `gravity`. (optional, default `false`)
+    -   `images[].density` **[Number][7]** number representing the DPI for vector overlay image. (optional, default `72`)
+    -   `images[].raw` **[Object][4]?** describes overlay when using raw pixel data.
+        -   `images[].raw.width` **[Number][7]?** 
+        -   `images[].raw.height` **[Number][7]?** 
+        -   `images[].raw.channels` **[Number][7]?** 
+    -   `images[].create` **[Object][4]?** describes a blank overlay to be created.
+        -   `images[].create.width` **[Number][7]?** 
+        -   `images[].create.height` **[Number][7]?** 
+        -   `images[].create.channels` **[Number][7]?** 3-4
+        -   `images[].create.background` **([String][6] \| [Object][4])?** parsed by the [color][9] module to extract values for red, green, blue and alpha.
+
+### Examples
+
+```javascript
+sharp('input.png')
+  .rotate(180)
+  .resize(300)
+  .flatten( { background: '#ff6600' } )
+  .composite([{ input: 'overlay.png', gravity: 'southeast' }])
+  .sharpen()
+  .withMetadata()
+  .webp( { quality: 90 } )
+  .toBuffer()
+  .then(function(outputBuffer) {
+    // outputBuffer contains upside down, 300px wide, alpha channel flattened
+    // onto orange background, composited with overlay.png with SE gravity,
+    // sharpened, with metadata, 90% quality WebP image data. Phew!
+  });
+```
+
+-   Throws **[Error][10]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://libvips.github.io/libvips/API/current/libvips-conversion.html#VipsBlendMode
+
+[2]: https://www.cairographics.org/operators/
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[5]: https://nodejs.org/api/buffer.html
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[9]: https://www.npmjs.org/package/color
+
+[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-constructor.md

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+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## Sharp
+
+### Parameters
+
+-   `input` **([Buffer][1] \| [String][2])?** if present, can be
+     a Buffer containing JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data, or
+     a String containing the path to an JPEG, PNG, WebP, GIF, SVG or TIFF image file.
+     JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data can be streamed into the object when not present.
+-   `options` **[Object][3]?** if present, is an Object with optional attributes.
+    -   `options.failOnError` **[Boolean][4]** by default halt processing and raise an error when loading invalid images.
+         Set this flag to `false` if you'd rather apply a "best effort" to decode images, even if the data is corrupt or invalid. (optional, default `true`)
+    -   `options.density` **[Number][5]** number representing the DPI for vector images. (optional, default `72`)
+    -   `options.pages` **[Number][5]** number of pages to extract for multi-page input (GIF, TIFF, PDF), use -1 for all pages. (optional, default `1`)
+    -   `options.page` **[Number][5]** page number to start extracting from for multi-page input (GIF, TIFF, PDF), zero based. (optional, default `0`)
+    -   `options.raw` **[Object][3]?** describes raw pixel input image data. See `raw()` for pixel ordering.
+        -   `options.raw.width` **[Number][5]?** 
+        -   `options.raw.height` **[Number][5]?** 
+        -   `options.raw.channels` **[Number][5]?** 1-4
+    -   `options.create` **[Object][3]?** describes a new image to be created.
+        -   `options.create.width` **[Number][5]?** 
+        -   `options.create.height` **[Number][5]?** 
+        -   `options.create.channels` **[Number][5]?** 3-4
+        -   `options.create.background` **([String][2] \| [Object][3])?** parsed by the [color][6] module to extract values for red, green, blue and alpha.
+
+### Examples
+
+```javascript
+sharp('input.jpg')
+  .resize(300, 200)
+  .toFile('output.jpg', function(err) {
+    // output.jpg is a 300 pixels wide and 200 pixels high image
+    // containing a scaled and cropped version of input.jpg
+  });
+```
+
+```javascript
+// Read image data from readableStream,
+// resize to 300 pixels wide,
+// emit an 'info' event with calculated dimensions
+// and finally write image data to writableStream
+var transformer = sharp()
+  .resize(300)
+  .on('info', function(info) {
+    console.log('Image height is ' + info.height);
+  });
+readableStream.pipe(transformer).pipe(writableStream);
+```
+
+```javascript
+// Create a blank 300x200 PNG image of semi-transluent red pixels
+sharp({
+  create: {
+    width: 300,
+    height: 200,
+    channels: 4,
+    background: { r: 255, g: 0, b: 0, alpha: 0.5 }
+  }
+})
+.png()
+.toBuffer()
+.then( ... );
+```
+
+-   Throws **[Error][7]** Invalid parameters
+
+Returns **[Sharp][8]** 
+
+### format
+
+An Object containing nested boolean values representing the available input and output formats/methods.
+
+#### Examples
+
+```javascript
+console.log(sharp.format);
+```
+
+Returns **[Object][3]** 
+
+### versions
+
+An Object containing the version numbers of libvips and its dependencies.
+
+#### Examples
+
+```javascript
+console.log(sharp.versions);
+```
+
+## queue
+
+An EventEmitter that emits a `change` event when a task is either:
+
+-   queued, waiting for _libuv_ to provide a worker thread
+-   complete
+
+### Examples
+
+```javascript
+sharp.queue.on('change', function(queueLength) {
+  console.log('Queue contains ' + queueLength + ' task(s)');
+});
+```
+
+[1]: https://nodejs.org/api/buffer.html
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[6]: https://www.npmjs.org/package/color
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[8]: #sharp

docs/api-input.md

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+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## clone
+
+Take a "snapshot" of the Sharp instance, returning a new instance.
+Cloned instances inherit the input of their parent instance.
+This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.
+
+### Examples
+
+```javascript
+const pipeline = sharp().rotate();
+pipeline.clone().resize(800, 600).pipe(firstWritableStream);
+pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
+readableStream.pipe(pipeline);
+// firstWritableStream receives auto-rotated, resized readableStream
+// secondWritableStream receives auto-rotated, extracted region of readableStream
+```
+
+Returns **Sharp** 
+
+## metadata
+
+Fast access to (uncached) image metadata without decoding any compressed image data.
+A `Promise` is returned when `callback` is not provided.
+
+-   `format`: Name of decoder used to decompress image data e.g. `jpeg`, `png`, `webp`, `gif`, `svg`
+-   `size`: Total size of image in bytes, for Stream and Buffer input only
+-   `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
+-   `height`: Number of pixels high (EXIF orientation is not taken into consideration)
+-   `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][1]
+-   `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+-   `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...][2]
+-   `density`: Number of pixels per inch (DPI), if present
+-   `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
+-   `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+-   `pages`: Number of pages/frames contained within the image, with support for TIFF, PDF, animated GIF and animated WebP
+-   `pageHeight`: Number of pixels high each page in this PDF image will be.
+-   `hasProfile`: Boolean indicating the presence of an embedded ICC profile
+-   `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
+-   `orientation`: Number value of the EXIF Orientation header, if present
+-   `exif`: Buffer containing raw EXIF data, if present
+-   `icc`: Buffer containing raw [ICC][3] profile data, if present
+-   `iptc`: Buffer containing raw IPTC data, if present
+-   `xmp`: Buffer containing raw XMP data, if present
+
+### Parameters
+
+-   `callback` **[Function][4]?** called with the arguments `(err, metadata)`
+
+### Examples
+
+```javascript
+const image = sharp(inputJpg);
+image
+  .metadata()
+  .then(function(metadata) {
+    return image
+      .resize(Math.round(metadata.width / 2))
+      .webp()
+      .toBuffer();
+  })
+  .then(function(data) {
+    // data contains a WebP image half the width and height of the original JPEG
+  });
+```
+
+Returns **([Promise][5]&lt;[Object][6]> | Sharp)** 
+
+## stats
+
+Access to pixel-derived image statistics for every channel in the image.
+A `Promise` is returned when `callback` is not provided.
+
+-   `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
+    -   `min` (minimum value in the channel)
+    -   `max` (maximum value in the channel)
+    -   `sum` (sum of all values in a channel)
+    -   `squaresSum` (sum of squared values in a channel)
+    -   `mean` (mean of the values in a channel)
+    -   `stdev` (standard deviation for the values in a channel)
+    -   `minX` (x-coordinate of one of the pixel where the minimum lies)
+    -   `minY` (y-coordinate of one of the pixel where the minimum lies)
+    -   `maxX` (x-coordinate of one of the pixel where the maximum lies)
+    -   `maxY` (y-coordinate of one of the pixel where the maximum lies)
+-   `isOpaque`: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel
+-   `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
+
+### Parameters
+
+-   `callback` **[Function][4]?** called with the arguments `(err, stats)`
+
+### Examples
+
+```javascript
+const image = sharp(inputJpg);
+image
+  .stats()
+  .then(function(stats) {
+     // stats contains the channel-wise statistics array and the isOpaque value
+  });
+```
+
+Returns **[Promise][5]&lt;[Object][6]>** 
+
+## limitInputPixels
+
+Do not process input images where the number of pixels (width x height) exceeds this limit.
+Assumes image dimensions contained in the input metadata can be trusted.
+The default limit is 268402689 (0x3FFF x 0x3FFF) pixels.
+
+### Parameters
+
+-   `limit` **([Number][7] \| [Boolean][8])** an integral Number of pixels, zero or false to remove limit, true to use default limit.
+
+
+-   Throws **[Error][9]** Invalid limit
+
+Returns **Sharp** 
+
+## sequentialRead
+
+An advanced setting that switches the libvips access method to `VIPS_ACCESS_SEQUENTIAL`.
+This will reduce memory usage and can improve performance on some systems.
+
+The default behaviour _before_ function call is `false`, meaning the libvips access method is not sequential.
+
+### Parameters
+
+-   `sequentialRead` **[Boolean][8]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+[1]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636
+
+[2]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672
+
+[3]: https://www.npmjs.com/package/icc
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-operation.md

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+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## rotate
+
+Rotate the output image by either an explicit angle
+or auto-orient based on the EXIF `Orientation` tag.
+
+If an angle is provided, it is converted to a valid positive degree rotation.
+For example, `-450` will produce a 270deg rotation.
+
+When rotating by an angle other than a multiple of 90,
+the background colour can be provided with the `background` option.
+
+If no angle is provided, it is determined from the EXIF data.
+Mirroring is supported and may infer the use of a flip operation.
+
+The use of `rotate` implies the removal of the EXIF `Orientation` tag, if any.
+
+Method order is important when both rotating and extracting regions,
+for example `rotate(x).extract(y)` will produce a different result to `extract(y).rotate(x)`.
+
+### Parameters
+
+-   `angle` **[Number][1]** angle of rotation. (optional, default `auto`)
+-   `options` **[Object][2]?** if present, is an Object with optional attributes.
+    -   `options.background` **([String][3] \| [Object][2])** parsed by the [color][4] module to extract values for red, green, blue and alpha. (optional, default `"#000000"`)
+
+### Examples
+
+```javascript
+const pipeline = sharp()
+  .rotate()
+  .resize(null, 200)
+  .toBuffer(function (err, outputBuffer, info) {
+    // outputBuffer contains 200px high JPEG image data,
+    // auto-rotated using EXIF Orientation tag
+    // info.width and info.height contain the dimensions of the resized image
+  });
+readableStream.pipe(pipeline);
+```
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## flip
+
+Flip the image about the vertical Y axis. This always occurs after rotation, if any.
+The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.
+
+### Parameters
+
+-   `flip` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## flop
+
+Flop the image about the horizontal X axis. This always occurs after rotation, if any.
+The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.
+
+### Parameters
+
+-   `flop` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## sharpen
+
+Sharpen the image.
+When used without parameters, performs a fast, mild sharpen of the output image.
+When a `sigma` is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space.
+Separate control over the level of sharpening in "flat" and "jagged" areas is available.
+
+### Parameters
+
+-   `sigma` **[Number][1]?** the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+-   `flat` **[Number][1]** the level of sharpening to apply to "flat" areas. (optional, default `1.0`)
+-   `jagged` **[Number][1]** the level of sharpening to apply to "jagged" areas. (optional, default `2.0`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## median
+
+Apply median filter.
+When used without parameters the default window is 3x3.
+
+### Parameters
+
+-   `size` **[Number][1]** square mask size: size x size (optional, default `3`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## blur
+
+Blur the image.
+When used without parameters, performs a fast, mild blur of the output image.
+When a `sigma` is provided, performs a slower, more accurate Gaussian blur.
+
+### Parameters
+
+-   `sigma` **[Number][1]?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## flatten
+
+Merge alpha transparency channel, if any, with a background.
+
+### Parameters
+
+-   `options` **[Object][2]?** 
+    -   `options.background` **([String][3] \| [Object][2])** background colour, parsed by the [color][4] module, defaults to black. (optional, default `{r:0,g:0,b:0}`)
+
+Returns **Sharp** 
+
+## gamma
+
+Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of `1/gamma`
+then increasing the encoding (brighten) post-resize at a factor of `gamma`.
+This can improve the perceived brightness of a resized image in non-linear colour spaces.
+JPEG and WebP input images will not take advantage of the shrink-on-load performance optimisation
+when applying a gamma correction.
+
+Supply a second argument to use a different output gamma value, otherwise the first value is used in both cases.
+
+### Parameters
+
+-   `gamma` **[Number][1]** value between 1.0 and 3.0. (optional, default `2.2`)
+-   `gammaOut` **[Number][1]?** value between 1.0 and 3.0. (optional, defaults to same as `gamma`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## negate
+
+Produce the "negative" of the image.
+
+### Parameters
+
+-   `negate` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalise
+
+Enhance output image contrast by stretching its luminance to cover the full dynamic range.
+
+### Parameters
+
+-   `normalise` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalize
+
+Alternative spelling of normalise.
+
+### Parameters
+
+-   `normalize` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## convolve
+
+Convolve the image with the specified kernel.
+
+### Parameters
+
+-   `kernel` **[Object][2]** 
+    -   `kernel.width` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.height` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.kernel` **[Array][7]&lt;[Number][1]>** Array of length `width*height` containing the kernel values.
+    -   `kernel.scale` **[Number][1]** the scale of the kernel in pixels. (optional, default `sum`)
+    -   `kernel.offset` **[Number][1]** the offset of the kernel in pixels. (optional, default `0`)
+
+### Examples
+
+```javascript
+sharp(input)
+  .convolve({
+    width: 3,
+    height: 3,
+    kernel: [-1, 0, 1, -2, 0, 2, -1, 0, 1]
+  })
+  .raw()
+  .toBuffer(function(err, data, info) {
+    // data contains the raw pixel data representing the convolution
+    // of the input image with the horizontal Sobel operator
+  });
+```
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## threshold
+
+Any pixel value greather than or equal to the threshold value will be set to 255, otherwise it will be set to 0.
+
+### Parameters
+
+-   `threshold` **[Number][1]** a value in the range 0-255 representing the level at which the threshold will be applied. (optional, default `128`)
+-   `options` **[Object][2]?** 
+    -   `options.greyscale` **[Boolean][6]** convert to single channel greyscale. (optional, default `true`)
+    -   `options.grayscale` **[Boolean][6]** alternative spelling for greyscale. (optional, default `true`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## boolean
+
+Perform a bitwise boolean operation with operand image.
+
+This operation creates an output image where each pixel is the result of
+the selected bitwise boolean `operation` between the corresponding pixels of the input images.
+
+### Parameters
+
+-   `operand` **([Buffer][8] \| [String][3])** Buffer containing image data or String containing the path to an image file.
+-   `operator` **[String][3]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+-   `options` **[Object][2]?** 
+    -   `options.raw` **[Object][2]?** describes operand when using raw pixel data.
+        -   `options.raw.width` **[Number][1]?** 
+        -   `options.raw.height` **[Number][1]?** 
+        -   `options.raw.channels` **[Number][1]?** 
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## linear
+
+Apply the linear formula a \* input + b to the image (levels adjustment)
+
+### Parameters
+
+-   `a` **[Number][1]** multiplier (optional, default `1.0`)
+-   `b` **[Number][1]** offset (optional, default `0.0`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## recomb
+
+Recomb the image with the specified matrix.
+
+### Parameters
+
+-   `inputMatrix`  
+-   `3x3` **[Array][7]&lt;[Array][7]&lt;[Number][1]>>** Recombination matrix
+
+### Examples
+
+```javascript
+sharp(input)
+  .recomb([
+   [0.3588, 0.7044, 0.1368],
+   [0.2990, 0.5870, 0.1140],
+   [0.2392, 0.4696, 0.0912],
+  ])
+  .raw()
+  .toBuffer(function(err, data, info) {
+    // data contains the raw pixel data after applying the recomb
+    // With this example input, a sepia filter has been applied
+  });
+```
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[4]: https://www.npmjs.org/package/color
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[8]: https://nodejs.org/api/buffer.html

docs/api-output.md

@@ -0,0 +1,326 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## toFile
+
+Write output image data to a file.
+
+If an explicit output format is not selected, it will be inferred from the extension,
+with JPEG, PNG, WebP, TIFF, DZI, and libvips' V format supported.
+Note that raw pixel data is only supported for buffer output.
+
+A `Promise` is returned when `callback` is not provided.
+
+### Parameters
+
+-   `fileOut` **[String][1]** the path to write the image data to.
+-   `callback` **[Function][2]?** called on completion with two arguments `(err, info)`.
+    `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+    `channels` and `premultiplied` (indicating if premultiplication was used).
+    When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+
+### Examples
+
+```javascript
+sharp(input)
+  .toFile('output.png', (err, info) => { ... });
+```
+
+```javascript
+sharp(input)
+  .toFile('output.png')
+  .then(info => { ... })
+  .catch(err => { ... });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **[Promise][4]&lt;[Object][5]>** when no callback is provided
+
+## toBuffer
+
+Write output to a Buffer.
+JPEG, PNG, WebP, TIFF and RAW output are supported.
+By default, the format will match the input image, except GIF and SVG input which become PNG output.
+
+`callback`, if present, gets three arguments `(err, data, info)` where:
+
+-   `err` is an error, if any.
+-   `data` is the output image data.
+-   `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+    `channels` and `premultiplied` (indicating if premultiplication was used).
+    When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+
+A `Promise` is returned when `callback` is not provided.
+
+### Parameters
+
+-   `options` **[Object][5]?** 
+    -   `options.resolveWithObject` **[Boolean][6]?** Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
+-   `callback` **[Function][2]?** 
+
+### Examples
+
+```javascript
+sharp(input)
+  .toBuffer((err, data, info) => { ... });
+```
+
+```javascript
+sharp(input)
+  .toBuffer()
+  .then(data => { ... })
+  .catch(err => { ... });
+```
+
+```javascript
+sharp(input)
+  .toBuffer({ resolveWithObject: true })
+  .then(({ data, info }) => { ... })
+  .catch(err => { ... });
+```
+
+Returns **[Promise][4]&lt;[Buffer][7]>** when no callback is provided
+
+## withMetadata
+
+Include all metadata (EXIF, XMP, IPTC) from the input image in the output image.
+The default behaviour, when `withMetadata` is not used, is to strip all metadata and convert to the device-independent sRGB colour space.
+This will also convert to and add a web-friendly sRGB ICC profile.
+
+### Parameters
+
+-   `withMetadata` **[Object][5]?** 
+    -   `withMetadata.orientation` **[Number][8]?** value between 1 and 8, used to update the EXIF `Orientation` tag.
+
+### Examples
+
+```javascript
+sharp('input.jpg')
+  .withMetadata()
+  .toFile('output-with-metadata.jpg')
+  .then(info => { ... });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+## jpeg
+
+Use these JPEG options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
+    -   `options.chromaSubsampling` **[String][1]** set to '4:4:4' to prevent chroma subsampling when quality &lt;= 90 (optional, default `'4:2:0'`)
+    -   `options.trellisQuantisation` **[Boolean][6]** apply trellis quantisation, requires mozjpeg (optional, default `false`)
+    -   `options.overshootDeringing` **[Boolean][6]** apply overshoot deringing, requires mozjpeg (optional, default `false`)
+    -   `options.optimiseScans` **[Boolean][6]** optimise progressive scans, forces progressive, requires mozjpeg (optional, default `false`)
+    -   `options.optimizeScans` **[Boolean][6]** alternative spelling of optimiseScans (optional, default `false`)
+    -   `options.optimiseCoding` **[Boolean][6]** optimise Huffman coding tables (optional, default `true`)
+    -   `options.optimizeCoding` **[Boolean][6]** alternative spelling of optimiseCoding (optional, default `true`)
+    -   `options.quantisationTable` **[Number][8]** quantization table to use, integer 0-8, requires mozjpeg (optional, default `0`)
+    -   `options.quantizationTable` **[Number][8]** alternative spelling of quantisationTable (optional, default `0`)
+    -   `options.force` **[Boolean][6]** force JPEG output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to very high quality JPEG output
+const data = await sharp(input)
+  .jpeg({
+    quality: 100,
+    chromaSubsampling: '4:4:4'
+  })
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## png
+
+Use these PNG options for output image.
+
+PNG output is always full colour at 8 or 16 bits per pixel.
+Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.
+
+### Parameters
+
+-   `options` **[Object][5]?** 
+    -   `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
+    -   `options.compressionLevel` **[Number][8]** zlib compression level, 0-9 (optional, default `9`)
+    -   `options.adaptiveFiltering` **[Boolean][6]** use adaptive row filtering (optional, default `false`)
+    -   `options.palette` **[Boolean][6]** quantise to a palette-based image with alpha transparency support, requires libimagequant (optional, default `false`)
+    -   `options.quality` **[Number][8]** use the lowest number of colours needed to achieve given quality, requires libimagequant (optional, default `100`)
+    -   `options.colours` **[Number][8]** maximum number of palette entries, requires libimagequant (optional, default `256`)
+    -   `options.colors` **[Number][8]** alternative spelling of `options.colours`, requires libimagequant (optional, default `256`)
+    -   `options.dither` **[Number][8]** level of Floyd-Steinberg error diffusion, requires libimagequant (optional, default `1.0`)
+    -   `options.force` **[Boolean][6]** force PNG output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to PNG output
+const data = await sharp(input)
+  .png()
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## webp
+
+Use these WebP options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.alphaQuality` **[Number][8]** quality of alpha layer, integer 0-100 (optional, default `100`)
+    -   `options.lossless` **[Boolean][6]** use lossless compression mode (optional, default `false`)
+    -   `options.nearLossless` **[Boolean][6]** use near_lossless compression mode (optional, default `false`)
+    -   `options.force` **[Boolean][6]** force WebP output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to lossless WebP output
+const data = await sharp(input)
+  .webp({ lossless: true })
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## tiff
+
+Use these TIFF options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.force` **[Boolean][6]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
+    -   `options.compression` **[Boolean][6]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
+    -   `options.predictor` **[Boolean][6]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
+    -   `options.pyramid` **[Boolean][6]** write an image pyramid (optional, default `false`)
+    -   `options.tile` **[Boolean][6]** write a tiled tiff (optional, default `false`)
+    -   `options.tileWidth` **[Boolean][6]** horizontal tile size (optional, default `256`)
+    -   `options.tileHeight` **[Boolean][6]** vertical tile size (optional, default `256`)
+    -   `options.xres` **[Number][8]** horizontal resolution in pixels/mm (optional, default `1.0`)
+    -   `options.yres` **[Number][8]** vertical resolution in pixels/mm (optional, default `1.0`)
+    -   `options.squash` **[Boolean][6]** squash 8-bit images down to 1 bit (optional, default `false`)
+
+### Examples
+
+```javascript
+// Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
+sharp('input.svg')
+  .tiff({
+    compression: 'lzw',
+    squash: true
+  })
+  .toFile('1-bpp-output.tiff')
+  .then(info => { ... });
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## raw
+
+Force output to be raw, uncompressed uint8 pixel data.
+
+### Examples
+
+```javascript
+// Extract raw RGB pixel data from JPEG input
+const { data, info } = await sharp('input.jpg')
+  .raw()
+  .toBuffer({ resolveWithObject: true });
+```
+
+Returns **Sharp** 
+
+## toFormat
+
+Force output to a given format.
+
+### Parameters
+
+-   `format` **([String][1] \| [Object][5])** as a String or an Object with an 'id' attribute
+-   `options` **[Object][5]** output options
+
+### Examples
+
+```javascript
+// Convert any input to PNG output
+const data = await sharp(input)
+  .toFormat('png')
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** unsupported format or options
+
+Returns **Sharp** 
+
+## tile
+
+Use tile-based deep zoom (image pyramid) output.
+Set the format and options for tile images via the `toFormat`, `jpeg`, `png` or `webp` functions.
+Use a `.zip` or `.szi` file extension with `toFile` to write to a compressed archive file format.
+
+Warning: multiple sharp instances concurrently producing tile output can expose a possible race condition in some versions of libgsf.
+
+### Parameters
+
+-   `tile` **[Object][5]?** 
+    -   `tile.size` **[Number][8]** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
+    -   `tile.overlap` **[Number][8]** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
+    -   `tile.angle` **[Number][8]** tile angle of rotation, must be a multiple of 90. (optional, default `0`)
+    -   `tile.depth` **[String][1]?** how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
+    -   `tile.container` **[String][1]** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
+    -   `tile.layout` **[String][1]** filesystem layout, possible values are `dz`, `zoomify` or `google`. (optional, default `'dz'`)
+
+### Examples
+
+```javascript
+sharp('input.tiff')
+  .png()
+  .tile({
+    size: 512
+  })
+  .toFile('output.dz', function(err, info) {
+    // output.dzi is the Deep Zoom XML definition
+    // output_files contains 512x512 tiles grouped by zoom level
+  });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[7]: https://nodejs.org/api/buffer.html
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

docs/api-resize.md

@@ -0,0 +1,234 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## resize
+
+Resize image to `width`, `height` or `width x height`.
+
+When both a `width` and `height` are provided, the possible methods by which the image should **fit** these are:
+
+-   `cover`: Crop to cover both provided dimensions (the default).
+-   `contain`: Embed within both provided dimensions.
+-   `fill`: Ignore the aspect ratio of the input and stretch to both provided dimensions.
+-   `inside`: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to both those specified.
+-   `outside`: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to both those specified.
+    Some of these values are based on the [object-fit][1] CSS property.
+
+When using a `fit` of `cover` or `contain`, the default **position** is `centre`. Other options are:
+
+-   `sharp.position`: `top`, `right top`, `right`, `right bottom`, `bottom`, `left bottom`, `left`, `left top`.
+-   `sharp.gravity`: `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` or `centre`.
+-   `sharp.strategy`: `cover` only, dynamically crop using either the `entropy` or `attention` strategy.
+    Some of these values are based on the [object-position][2] CSS property.
+
+The experimental strategy-based approach resizes so one dimension is at its target length
+then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.
+
+-   `entropy`: focus on the region with the highest [Shannon entropy][3].
+-   `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.
+
+Possible interpolation kernels are:
+
+-   `nearest`: Use [nearest neighbour interpolation][4].
+-   `cubic`: Use a [Catmull-Rom spline][5].
+-   `mitchell`: Use a [Mitchell-Netravali spline][6].
+-   `lanczos2`: Use a [Lanczos kernel][7] with `a=2`.
+-   `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
+
+### Parameters
+
+-   `width` **[Number][8]?** pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
+-   `height` **[Number][8]?** pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
+-   `options` **[Object][9]?** 
+    -   `options.width` **[String][10]?** alternative means of specifying `width`. If both are present this take priority.
+    -   `options.height` **[String][10]?** alternative means of specifying `height`. If both are present this take priority.
+    -   `options.fit` **[String][10]** how the image should be resized to fit both provided dimensions, one of `cover`, `contain`, `fill`, `inside` or `outside`. (optional, default `'cover'`)
+    -   `options.position` **[String][10]** position, gravity or strategy to use when `fit` is `cover` or `contain`. (optional, default `'centre'`)
+    -   `options.background` **([String][10] \| [Object][9])** background colour when using a `fit` of `contain`, parsed by the [color][11] module, defaults to black without transparency. (optional, default `{r:0,g:0,b:0,alpha:1}`)
+    -   `options.kernel` **[String][10]** the kernel to use for image reduction. (optional, default `'lanczos3'`)
+    -   `options.withoutEnlargement` **[Boolean][12]** do not enlarge if the width _or_ height are already less than the specified dimensions, equivalent to GraphicsMagick's `>` geometry option. (optional, default `false`)
+    -   `options.fastShrinkOnLoad` **[Boolean][12]** take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images. (optional, default `true`)
+
+### Examples
+
+```javascript
+sharp(input)
+  .resize({ width: 100 })
+  .toBuffer()
+  .then(data => {
+    // 100 pixels wide, auto-scaled height
+  });
+```
+
+```javascript
+sharp(input)
+  .resize({ height: 100 })
+  .toBuffer()
+  .then(data => {
+    // 100 pixels high, auto-scaled width
+  });
+```
+
+```javascript
+sharp(input)
+  .resize(200, 300, {
+    kernel: sharp.kernel.nearest,
+    fit: 'contain',
+    position: 'right top',
+    background: { r: 255, g: 255, b: 255, alpha: 0.5 }
+  })
+  .toFile('output.png')
+  .then(() => {
+    // output.png is a 200 pixels wide and 300 pixels high image
+    // containing a nearest-neighbour scaled version
+    // contained within the north-east corner of a semi-transparent white canvas
+  });
+```
+
+```javascript
+const transformer = sharp()
+  .resize({
+    width: 200,
+    height: 200,
+    fit: sharp.fit.cover,
+    position: sharp.strategy.entropy
+  });
+// Read image data from readableStream
+// Write 200px square auto-cropped image data to writableStream
+readableStream
+  .pipe(transformer)
+  .pipe(writableStream);
+```
+
+```javascript
+sharp(input)
+  .resize(200, 200, {
+    fit: sharp.fit.inside,
+    withoutEnlargement: true
+  })
+  .toFormat('jpeg')
+  .toBuffer()
+  .then(function(outputBuffer) {
+    // outputBuffer contains JPEG image data
+    // no wider and no higher than 200 pixels
+    // and no larger than the input image
+  });
+```
+
+-   Throws **[Error][13]** Invalid parameters
+
+Returns **Sharp** 
+
+## extend
+
+Extends/pads the edges of the image with the provided background colour.
+This operation will always occur after resizing and extraction, if any.
+
+### Parameters
+
+-   `extend` **([Number][8] \| [Object][9])** single pixel count to add to all edges or an Object with per-edge counts
+    -   `extend.top` **[Number][8]?** 
+    -   `extend.left` **[Number][8]?** 
+    -   `extend.bottom` **[Number][8]?** 
+    -   `extend.right` **[Number][8]?** 
+    -   `extend.background` **([String][10] \| [Object][9])** background colour, parsed by the [color][11] module, defaults to black without transparency. (optional, default `{r:0,g:0,b:0,alpha:1}`)
+
+### Examples
+
+```javascript
+// Resize to 140 pixels wide, then add 10 transparent pixels
+// to the top, left and right edges and 20 to the bottom edge
+sharp(input)
+  .resize(140)
+  .extend({
+    top: 10,
+    bottom: 20,
+    left: 10,
+    right: 10,
+    background: { r: 0, g: 0, b: 0, alpha: 0 }
+  })
+  ...
+```
+
+-   Throws **[Error][13]** Invalid parameters
+
+Returns **Sharp** 
+
+## extract
+
+Extract a region of the image.
+
+-   Use `extract` before `resize` for pre-resize extraction.
+-   Use `extract` after `resize` for post-resize extraction.
+-   Use `extract` before and after for both.
+
+### Parameters
+
+-   `options` **[Object][9]** 
+    -   `options.left` **[Number][8]** zero-indexed offset from left edge
+    -   `options.top` **[Number][8]** zero-indexed offset from top edge
+    -   `options.width` **[Number][8]** dimension of extracted image
+    -   `options.height` **[Number][8]** dimension of extracted image
+
+### Examples
+
+```javascript
+sharp(input)
+  .extract({ left: left, top: top, width: width, height: height })
+  .toFile(output, function(err) {
+    // Extract a region of the input image, saving in the same format.
+  });
+```
+
+```javascript
+sharp(input)
+  .extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
+  .resize(width, height)
+  .extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
+  .toFile(output, function(err) {
+    // Extract a region, resize, then extract from the resized image
+  });
+```
+
+-   Throws **[Error][13]** Invalid parameters
+
+Returns **Sharp** 
+
+## trim
+
+Trim "boring" pixels from all edges that contain values similar to the top-left pixel.
+The `info` response Object will contain `trimOffsetLeft` and `trimOffsetTop` properties.
+
+### Parameters
+
+-   `threshold` **[Number][8]** the allowed difference from the top-left pixel, a number greater than zero. (optional, default `10`)
+
+
+-   Throws **[Error][13]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit
+
+[2]: https://developer.mozilla.org/en-US/docs/Web/CSS/object-position
+
+[3]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29
+
+[4]: http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation
+
+[5]: https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
+
+[6]: https://www.cs.utexas.edu/~fussell/courses/cs384g-fall2013/lectures/mitchell/Mitchell.pdf
+
+[7]: https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[11]: https://www.npmjs.org/package/color
+
+[12]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[13]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-utility.md

@@ -0,0 +1,102 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## cache
+
+Gets or, when options are provided, sets the limits of _libvips'_ operation cache.
+Existing entries in the cache will be trimmed after any change in limits.
+This method always returns cache statistics,
+useful for determining how much working memory is required for a particular task.
+
+### Parameters
+
+-   `options` **([Object][1] \| [Boolean][2])** Object with the following attributes, or Boolean where true uses default cache settings and false removes all caching (optional, default `true`)
+    -   `options.memory` **[Number][3]** is the maximum memory in MB to use for this cache (optional, default `50`)
+    -   `options.files` **[Number][3]** is the maximum number of files to hold open (optional, default `20`)
+    -   `options.items` **[Number][3]** is the maximum number of operations to cache (optional, default `100`)
+
+### Examples
+
+```javascript
+const stats = sharp.cache();
+```
+
+```javascript
+sharp.cache( { items: 200 } );
+sharp.cache( { files: 0 } );
+sharp.cache(false);
+```
+
+Returns **[Object][1]** 
+
+## concurrency
+
+Gets or, when a concurrency is provided, sets
+the number of threads _libvips'_ should create to process each image.
+The default value is the number of CPU cores.
+A value of `0` will reset to this default.
+
+The maximum number of images that can be processed in parallel
+is limited by libuv's `UV_THREADPOOL_SIZE` environment variable.
+
+This method always returns the current concurrency.
+
+### Parameters
+
+-   `concurrency` **[Number][3]?** 
+
+### Examples
+
+```javascript
+const threads = sharp.concurrency(); // 4
+sharp.concurrency(2); // 2
+sharp.concurrency(0); // 4
+```
+
+Returns **[Number][3]** concurrency
+
+## counters
+
+Provides access to internal task counters.
+
+-   queue is the number of tasks this module has queued waiting for _libuv_ to provide a worker thread from its pool.
+-   process is the number of resize tasks currently being processed.
+
+### Examples
+
+```javascript
+const counters = sharp.counters(); // { queue: 2, process: 4 }
+```
+
+Returns **[Object][1]** 
+
+## simd
+
+Get and set use of SIMD vector unit instructions.
+Requires libvips to have been compiled with liborc support.
+
+Improves the performance of `resize`, `blur` and `sharpen` operations
+by taking advantage of the SIMD vector unit of the CPU, e.g. Intel SSE and ARM NEON.
+
+### Parameters
+
+-   `simd` **[Boolean][2]**  (optional, default `true`)
+
+### Examples
+
+```javascript
+const simd = sharp.simd();
+// simd is `true` if the runtime use of liborc is currently enabled
+```
+
+```javascript
+const simd = sharp.simd(false);
+// prevent libvips from using liborc at runtime
+```
+
+Returns **[Boolean][2]** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

docs/changelog.md

@@ -0,0 +1,926 @@
+# Changelog
+
+### v0.22 - "*uptake*"
+
+Requires libvips v8.7.4.
+
+#### v0.22.0 - 18<sup>th</sup> March 2019
+
+* Remove functions previously deprecated in v0.21.0:
+    `background`, `crop`, `embed`, `ignoreAspectRatio`, `max`, `min` and `withoutEnlargement`.
+
+* Add `composite` operation supporting multiple images and blend modes; deprecate `overlayWith`.
+  [#728](https://github.com/lovell/sharp/issues/728)
+
+* Add support for `pages` input option for multi-page input.
+  [#1566](https://github.com/lovell/sharp/issues/1566)
+
+* Allow Stream-based input of raw pixel data.
+  [#1579](https://github.com/lovell/sharp/issues/1579)
+
+* Add support for `page` input option to GIF and PDF.
+  [#1595](https://github.com/lovell/sharp/pull/1595)
+  [@ramiel](https://github.com/ramiel)
+
+### v0.21 - "*teeth*"
+
+Requires libvips v8.7.0.
+
+#### v0.21.3 - 19<sup>th</sup> January 2019
+
+* Input image decoding now fails fast, set `failOnError` to change this behaviour.
+
+* Failed filesystem-based input now separates missing file and invalid format errors.
+  [#1542](https://github.com/lovell/sharp/issues/1542)
+
+#### v0.21.2 - 13<sup>th</sup> January 2019
+
+* Ensure all metadata is removed from PNG output unless `withMetadata` used.
+
+* Ensure shortest edge is at least one pixel after resizing.
+  [#1003](https://github.com/lovell/sharp/issues/1003)
+
+* Add `ensureAlpha` operation to add an alpha channel, if missing.
+  [#1153](https://github.com/lovell/sharp/issues/1153)
+
+* Expose `pages` and `pageHeight` metadata for multi-page input images.
+  [#1205](https://github.com/lovell/sharp/issues/1205)
+
+* Expose PNG output options requiring libimagequant.
+  [#1484](https://github.com/lovell/sharp/issues/1484)
+
+* Expose underlying error message for invalid input.
+  [#1505](https://github.com/lovell/sharp/issues/1505)
+
+* Prevent mutatation of options passed to `jpeg`.
+  [#1516](https://github.com/lovell/sharp/issues/1516)
+
+* Ensure forced output format applied correctly when output chaining.
+  [#1528](https://github.com/lovell/sharp/issues/1528)
+
+#### v0.21.1 - 7<sup>th</sup> December 2018
+
+* Install: support `sharp_dist_base_url` npm config, like existing `SHARP_DIST_BASE_URL`.
+  [#1422](https://github.com/lovell/sharp/pull/1422)
+  [@SethWen](https://github.com/SethWen)
+
+* Ensure `channel` metadata is correct for raw, greyscale output.
+  [#1425](https://github.com/lovell/sharp/issues/1425)
+
+* Add support for the "mitchell" kernel for image reductions.
+  [#1438](https://github.com/lovell/sharp/pull/1438)
+  [@Daiz](https://github.com/Daiz)
+
+* Allow separate parameters for gamma encoding and decoding.
+  [#1439](https://github.com/lovell/sharp/pull/1439)
+  [@Daiz](https://github.com/Daiz)
+
+* Build prototype with `Object.assign` to allow minification.
+  [#1475](https://github.com/lovell/sharp/pull/1475)
+  [@jaubourg](https://github.com/jaubourg)
+
+* Expose libvips' recombination matrix operation.
+  [#1477](https://github.com/lovell/sharp/pull/1477)
+  [@fromkeith](https://github.com/fromkeith)
+
+* Expose libvips' pyramid/tile options for TIFF output.
+  [#1483](https://github.com/lovell/sharp/pull/1483)
+  [@mbklein](https://github.com/mbklein)
+
+#### v0.21.0 - 4<sup>th</sup> October 2018
+
+* Deprecate the following resize-related functions:
+    `crop`, `embed`, `ignoreAspectRatio`, `max`, `min` and `withoutEnlargement`.
+  Access to these is now via options passed to the `resize` function.
+  For example:
+    `embed('north')` is now `resize(width, height, { fit: 'contain', position: 'north' })`,
+    `crop('attention')` is now `resize(width, height, { fit: 'cover', position: 'attention' })`,
+    `max().withoutEnlargement()` is now `resize(width, height, { fit: 'inside', withoutEnlargement: true })`.
+  [#1135](https://github.com/lovell/sharp/issues/1135)
+
+* Deprecate the `background` function.
+    Per-operation `background` options added to `resize`, `extend` and `flatten` operations.
+  [#1392](https://github.com/lovell/sharp/issues/1392)
+
+* Add `size` to `metadata` response (Stream and Buffer input only).
+  [#695](https://github.com/lovell/sharp/issues/695)
+
+* Switch from custom trim operation to `vips_find_trim`.
+  [#914](https://github.com/lovell/sharp/issues/914)
+
+* Add `chromaSubsampling` and `isProgressive` properties to `metadata` response.
+  [#1186](https://github.com/lovell/sharp/issues/1186)
+
+* Drop Node 4 support.
+  [#1212](https://github.com/lovell/sharp/issues/1212)
+
+* Enable SIMD convolution by default.
+  [#1213](https://github.com/lovell/sharp/issues/1213)
+
+* Add experimental prebuilt binaries for musl-based Linux.
+  [#1379](https://github.com/lovell/sharp/issues/1379)
+
+* Add support for arbitrary rotation angle via vips_rotate.
+  [#1385](https://github.com/lovell/sharp/pull/1385)
+  [@freezy](https://github.com/freezy)
+
+### v0.20 - "*prebuild*"
+
+Requires libvips v8.6.1.
+
+#### v0.20.8 - 5<sup>th</sup> September 2018
+
+* Avoid race conditions when creating directories during installation.
+  [#1358](https://github.com/lovell/sharp/pull/1358)
+  [@ajhool](https://github.com/ajhool)
+
+* Accept floating point values for input density parameter.
+  [#1362](https://github.com/lovell/sharp/pull/1362)
+  [@aeirola](https://github.com/aeirola)
+
+#### v0.20.7 - 21<sup>st</sup> August 2018
+
+* Use copy+unlink if rename operation fails during installation.
+  [#1345](https://github.com/lovell/sharp/issues/1345)
+
+#### v0.20.6 - 20<sup>th</sup> August 2018
+
+* Add removeAlpha operation to remove alpha channel, if any.
+  [#1248](https://github.com/lovell/sharp/issues/1248)
+
+* Expose mozjpeg quant_table flag.
+  [#1285](https://github.com/lovell/sharp/pull/1285)
+  [@rexxars](https://github.com/rexxars)
+
+* Allow full WebP alphaQuality range of 0-100.
+  [#1290](https://github.com/lovell/sharp/pull/1290)
+  [@sylvaindumont](https://github.com/sylvaindumont)
+
+* Cache libvips binaries to reduce re-install time.
+  [#1301](https://github.com/lovell/sharp/issues/1301)
+
+* Ensure vendor platform mismatch throws error at install time.
+  [#1303](https://github.com/lovell/sharp/issues/1303)
+
+* Improve install time error messages for FreeBSD users.
+  [#1310](https://github.com/lovell/sharp/issues/1310)
+
+* Ensure extractChannel works with 16-bit images.
+  [#1330](https://github.com/lovell/sharp/issues/1330)
+
+* Expose depth option for tile-based output.
+  [#1342](https://github.com/lovell/sharp/pull/1342)
+  [@alundavies](https://github.com/alundavies)
+
+* Add experimental entropy field to stats response.
+
+#### v0.20.5 - 27<sup>th</sup> June 2018
+
+* Expose libjpeg optimize_coding flag.
+  [#1265](https://github.com/lovell/sharp/pull/1265)
+  [@tomlokhorst](https://github.com/tomlokhorst)
+
+#### v0.20.4 - 20<sup>th</sup> June 2018
+
+* Prevent possible rounding error when using shrink-on-load and 90/270 degree rotation.
+  [#1241](https://github.com/lovell/sharp/issues/1241)
+  [@anahit42](https://github.com/anahit42)
+
+* Ensure extractChannel sets correct single-channel colour space interpretation.
+  [#1257](https://github.com/lovell/sharp/issues/1257)
+  [@jeremychone](https://github.com/jeremychone)
+
+#### v0.20.3 - 29<sup>th</sup> May 2018
+
+* Fix tint operation by ensuring LAB interpretation and allowing negative values.
+  [#1235](https://github.com/lovell/sharp/issues/1235)
+  [@wezside](https://github.com/wezside)
+
+#### v0.20.2 - 28<sup>th</sup> April 2018
+
+* Add tint operation to set image chroma.
+  [#825](https://github.com/lovell/sharp/pull/825)
+  [@rikh42](https://github.com/rikh42)
+
+* Add environment variable to ignore globally-installed libvips.
+  [#1165](https://github.com/lovell/sharp/pull/1165)
+  [@oncletom](https://github.com/oncletom)
+
+* Add support for page selection with multi-page input (GIF/TIFF).
+  [#1204](https://github.com/lovell/sharp/pull/1204)
+  [@woolite64](https://github.com/woolite64)
+
+* Add support for Group4 (CCITTFAX4) compression with TIFF output.
+  [#1208](https://github.com/lovell/sharp/pull/1208)
+  [@woolite64](https://github.com/woolite64)
+
+#### v0.20.1 - 17<sup>th</sup> March 2018
+
+* Improve installation experience when a globally-installed libvips below the minimum required version is found.
+  [#1148](https://github.com/lovell/sharp/issues/1148)
+
+* Prevent smartcrop error when cumulative rounding is below target size.
+  [#1154](https://github.com/lovell/sharp/issues/1154)
+  [@ralrom](https://github.com/ralrom)
+
+* Expose libvips' median filter operation.
+  [#1161](https://github.com/lovell/sharp/pull/1161)
+  [@BiancoA](https://github.com/BiancoA)
+
+#### v0.20.0 - 5<sup>th</sup> March 2018
+
+* Add support for prebuilt sharp binaries on common platforms.
+  [#186](https://github.com/lovell/sharp/issues/186)
+
+### v0.19 - "*suit*"
+
+Requires libvips v8.6.1.
+
+#### v0.19.1 - 24<sup>th</sup> February 2018
+
+* Expose libvips' linear transform feature.
+  [#1024](https://github.com/lovell/sharp/pull/1024)
+  [@3epnm](https://github.com/3epnm)
+
+* Expose angle option for tile-based output.
+  [#1121](https://github.com/lovell/sharp/pull/1121)
+  [@BiancoA](https://github.com/BiancoA)
+
+* Prevent crop operation when image already at or below target dimensions.
+  [#1134](https://github.com/lovell/sharp/issues/1134)
+  [@pieh](https://github.com/pieh)
+
+#### v0.19.0 - 11<sup>th</sup> January 2018
+
+* Expose offset coordinates of strategy-based crop.
+  [#868](https://github.com/lovell/sharp/issues/868)
+  [@mirohristov-com](https://github.com/mirohristov-com)
+
+* PNG output now defaults to adaptiveFiltering=false, compressionLevel=9
+  [#872](https://github.com/lovell/sharp/issues/872)
+  [@wmertens](https://github.com/wmertens)
+
+* Add stats feature for pixel-derived image statistics.
+  [#915](https://github.com/lovell/sharp/pull/915)
+  [@rnanwani](https://github.com/rnanwani)
+
+* Add failOnError option to fail-fast on bad input image data.
+  [#976](https://github.com/lovell/sharp/pull/976)
+  [@mceachen](https://github.com/mceachen)
+
+* Resize: switch to libvips' implementation, make fastShrinkOnLoad optional, remove interpolator and centreSampling options.
+  [#977](https://github.com/lovell/sharp/pull/977)
+  [@jardakotesovec](https://github.com/jardakotesovec)
+
+* Attach finish event listener to a clone only for Stream-based input.
+  [#995](https://github.com/lovell/sharp/issues/995)
+  [@whmountains](https://github.com/whmountains)
+
+* Add tilecache before smartcrop to avoid over-computation of previous operations.
+  [#1028](https://github.com/lovell/sharp/issues/1028)
+  [@coffeebite](https://github.com/coffeebite)
+
+* Prevent toFile extension taking precedence over requested format.
+  [#1037](https://github.com/lovell/sharp/issues/1037)
+  [@tomgallagher](https://github.com/tomgallagher)
+
+* Add support for gravity option to existing embed feature.
+  [#1038](https://github.com/lovell/sharp/pull/1038)
+  [@AzureByte](https://github.com/AzureByte)
+
+* Expose IPTC and XMP metadata when available.
+  [#1079](https://github.com/lovell/sharp/pull/1079)
+  [@oaleynik](https://github.com/oaleynik)
+
+* TIFF output: switch default predictor from 'none' to 'horizontal' to match libvips' behaviour.
+
+### v0.18 - "*ridge*"
+
+Requires libvips v8.5.5.
+
+#### v0.18.4 - 18<sup>th</sup> September 2017
+
+* Ensure input Buffer really is marked as Persistent, prevents mark-sweep GC.
+  [#950](https://github.com/lovell/sharp/issues/950)
+  [@lfdoherty](https://github.com/lfdoherty)
+
+#### v0.18.3 - 13<sup>th</sup> September 2017
+
+* Skip shrink-on-load when trimming.
+  [#888](https://github.com/lovell/sharp/pull/888)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Migrate from got to simple-get for basic auth support.
+  [#945](https://github.com/lovell/sharp/pull/945)
+  [@pbomb](https://github.com/pbomb)
+
+#### v0.18.2 - 1<sup>st</sup> July 2017
+
+* Expose libvips' xres and yres properties for TIFF output.
+  [#828](https://github.com/lovell/sharp/pull/828)
+  [@YvesBos](https://github.com/YvesBos)
+
+* Ensure flip and flop operations work with auto-rotate.
+  [#837](https://github.com/lovell/sharp/issues/837)
+  [@rexxars](https://github.com/rexxars)
+
+* Allow binary download URL override via SHARP_DIST_BASE_URL env variable.
+  [#841](https://github.com/lovell/sharp/issues/841)
+
+* Add support for Solus Linux.
+  [#857](https://github.com/lovell/sharp/pull/857)
+  [@ekremkaraca](https://github.com/ekremkaraca)
+
+#### v0.18.1 - 30<sup>th</sup> May 2017
+
+* Remove regression from #781 that could cause incorrect shrink calculation.
+  [#831](https://github.com/lovell/sharp/issues/831)
+  [@suprMax](https://github.com/suprMax)
+
+#### v0.18.0 - 30<sup>th</sup> May 2017
+
+* Remove the previously-deprecated output format "option" functions:
+    quality, progressive, compressionLevel, withoutAdaptiveFiltering,
+    withoutChromaSubsampling, trellisQuantisation, trellisQuantization,
+    overshootDeringing, optimiseScans and optimizeScans.
+
+* Ensure maximum output dimensions are based on the format to be used.
+  [#176](https://github.com/lovell/sharp/issues/176)
+  [@stephanebachelier](https://github.com/stephanebachelier)
+
+* Avoid costly (un)premultiply when using overlayWith without alpha channel.
+  [#573](https://github.com/lovell/sharp/issues/573)
+  [@strarsis](https://github.com/strarsis)
+
+* Include pixel depth (e.g. "uchar") when reading metadata.
+  [#577](https://github.com/lovell/sharp/issues/577)
+  [@moedusa](https://github.com/moedusa)
+
+* Add support for Buffer and Stream-based TIFF output.
+  [#587](https://github.com/lovell/sharp/issues/587)
+  [@strarsis](https://github.com/strarsis)
+
+* Expose warnings from libvips via NODE_DEBUG=sharp environment variable.
+  [#607](https://github.com/lovell/sharp/issues/607)
+  [@puzrin](https://github.com/puzrin)
+
+* Switch to the libvips implementation of "attention" and "entropy" crop strategies.
+  [#727](https://github.com/lovell/sharp/issues/727)
+
+* Improve performance and accuracy of nearest neighbour integral upsampling.
+  [#752](https://github.com/lovell/sharp/issues/752)
+  [@MrIbby](https://github.com/MrIbby)
+
+* Constructor single argument API: allow plain object, reject null/undefined.
+  [#768](https://github.com/lovell/sharp/issues/768)
+  [@kub1x](https://github.com/kub1x)
+
+* Ensure ARM64 pre-built binaries use correct C++11 ABI version.
+  [#772](https://github.com/lovell/sharp/issues/772)
+  [@ajiratech2](https://github.com/ajiratech2)
+
+* Prevent aliasing by using dynamic values for shrink(-on-load).
+  [#781](https://github.com/lovell/sharp/issues/781)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Expose libvips' "squash" parameter to enable 1-bit TIFF output.
+  [#783](https://github.com/lovell/sharp/pull/783)
+  [@YvesBos](https://github.com/YvesBos)
+
+* Add support for rotation using any multiple of +/-90 degrees.
+  [#791](https://github.com/lovell/sharp/pull/791)
+  [@ncoden](https://github.com/ncoden)
+
+* Add "jpg" alias to toFormat as shortened form of "jpeg".
+  [#814](https://github.com/lovell/sharp/pull/814)
+  [@jingsam](https://github.com/jingsam)
+
+### v0.17 - "*quill*"
+
+Requires libvips v8.4.2.
+
+#### v0.17.3 - 1<sup>st</sup> April 2017
+
+* Allow toBuffer to optionally resolve a Promise with both info and data.
+  [#143](https://github.com/lovell/sharp/issues/143)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Create blank image of given width, height, channels and background.
+  [#470](https://github.com/lovell/sharp/issues/470)
+  [@pjarts](https://github.com/pjarts)
+
+* Add support for the "nearest" kernel for image reductions.
+  [#732](https://github.com/lovell/sharp/pull/732)
+  [@alice0meta](https://github.com/alice0meta)
+
+* Add support for TIFF compression and predictor options.
+  [#738](https://github.com/lovell/sharp/pull/738)
+  [@kristojorg](https://github.com/kristojorg)
+
+#### v0.17.2 - 11<sup>th</sup> February 2017
+
+* Ensure Readable side of Stream can start flowing after Writable side has finished.
+  [#671](https://github.com/lovell/sharp/issues/671)
+  [@danhaller](https://github.com/danhaller)
+
+* Expose WebP alpha quality, lossless and near-lossless output options.
+  [#685](https://github.com/lovell/sharp/pull/685)
+  [@rnanwani](https://github.com/rnanwani)
+
+#### v0.17.1 - 15<sup>th</sup> January 2017
+
+* Improve error messages for invalid parameters.
+  [@spikeon](https://github.com/spikeon)
+  [#644](https://github.com/lovell/sharp/pull/644)
+
+* Simplify expression for finding vips-cpp libdir.
+  [#656](https://github.com/lovell/sharp/pull/656)
+
+* Allow HTTPS-over-HTTP proxy when downloading pre-compiled dependencies.
+  [@wangzhiwei1888](https://github.com/wangzhiwei1888)
+  [#679](https://github.com/lovell/sharp/issues/679)
+
+#### v0.17.0 - 11<sup>th</sup> December 2016
+
+* Drop support for versions of Node prior to v4.
+
+* Deprecate the following output format "option" functions:
+    quality, progressive, compressionLevel, withoutAdaptiveFiltering,
+    withoutChromaSubsampling, trellisQuantisation, trellisQuantization,
+    overshootDeringing, optimiseScans and optimizeScans.
+  Access to these is now via output format functions, for example `quality(n)`
+    is now `jpeg({quality: n})` and/or `webp({quality: n})`.
+
+* Autoconvert GIF and SVG input to PNG output if no other format is specified.
+
+* Expose libvips' "centre" resize option to mimic \*magick's +0.5px convention.
+  [#568](https://github.com/lovell/sharp/issues/568)
+
+* Ensure support for embedded base64 PNG and JPEG images within an SVG.
+  [#601](https://github.com/lovell/sharp/issues/601)
+  [@dynamite-ready](https://github.com/dynamite-ready)
+
+* Ensure premultiply operation occurs before box filter shrink.
+  [#605](https://github.com/lovell/sharp/issues/605)
+  [@CmdrShepardsPie](https://github.com/CmdrShepardsPie)
+  [@teroparvinen](https://github.com/teroparvinen)
+
+* Add support for PNG and WebP tile-based output formats (in addition to JPEG).
+  [#622](https://github.com/lovell/sharp/pull/622)
+  [@ppaskaris](https://github.com/ppaskaris)
+
+* Allow use of extend with greyscale input.
+  [#623](https://github.com/lovell/sharp/pull/623)
+  [@ppaskaris](https://github.com/ppaskaris)
+
+* Allow non-RGB input to embed/extend onto background with an alpha channel.
+  [#646](https://github.com/lovell/sharp/issues/646)
+  [@DaGaMs](https://github.com/DaGaMs)
+
+### v0.16 - "*pencil*"
+
+Requires libvips v8.3.3
+
+#### v0.16.2 - 22<sup>nd</sup> October 2016
+
+* Restrict readelf usage to Linux only when detecting global libvips version.
+  [#602](https://github.com/lovell/sharp/issues/602)
+  [@caoko](https://github.com/caoko)
+
+#### v0.16.1 - 13<sup>th</sup> October 2016
+
+* C++11 ABI version is now auto-detected, remove sharp-cxx11 installation flag.
+
+* Add experimental 'attention' crop strategy.
+  [#295](https://github.com/lovell/sharp/issues/295)
+
+* Include .node extension for Meteor's require() implementation.
+  [#537](https://github.com/lovell/sharp/issues/537)
+  [@isjackwild](https://github.com/isjackwild)
+
+* Ensure convolution kernel scale is clamped to a minimum value of 1.
+  [#561](https://github.com/lovell/sharp/issues/561)
+  [@abagshaw](https://github.com/abagshaw)
+
+* Correct calculation of y-axis placement when overlaying image at a fixed point.
+  [#566](https://github.com/lovell/sharp/issues/566)
+  [@Nateowami](https://github.com/Nateowami)
+
+#### v0.16.0 - 18<sup>th</sup> August 2016
+
+* Add pre-compiled libvips for OS X, ARMv7 and ARMv8.
+  [#312](https://github.com/lovell/sharp/issues/312)
+
+* Ensure boolean, bandbool, extractChannel ops occur before sRGB conversion.
+  [#504](https://github.com/lovell/sharp/pull/504)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Recalculate factors after WebP shrink-on-load to avoid round-to-zero errors.
+  [#508](https://github.com/lovell/sharp/issues/508)
+  [@asilvas](https://github.com/asilvas)
+
+* Prevent boolean errors during extract operation.
+  [#511](https://github.com/lovell/sharp/pull/511)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add joinChannel and toColourspace/toColorspace operations.
+  [#513](https://github.com/lovell/sharp/pull/513)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add support for raw pixel data with boolean and withOverlay operations.
+  [#516](https://github.com/lovell/sharp/pull/516)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Prevent bandbool creating a single channel sRGB image.
+  [#519](https://github.com/lovell/sharp/pull/519)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Ensure ICC profiles are removed from PNG output unless withMetadata used.
+  [#521](https://github.com/lovell/sharp/issues/521)
+  [@ChrisPinewood](https://github.com/ChrisPinewood)
+
+* Add alpha channels, if missing, to overlayWith images.
+  [#540](https://github.com/lovell/sharp/pull/540)
+  [@cmtt](https://github.com/cmtt)
+
+* Remove deprecated interpolateWith method - use resize(w, h, { interpolator: ... })
+  [#310](https://github.com/lovell/sharp/issues/310)
+
+### v0.15 - "*outfit*"
+
+Requires libvips v8.3.1
+
+#### v0.15.1 - 12<sup>th</sup> July 2016
+
+* Concat Stream-based input in single operation for ~+3% perf and less GC.
+  [#429](https://github.com/lovell/sharp/issues/429)
+  [@papandreou](https://github.com/papandreou)
+
+* Add alpha channel, if required, before extend operation.
+  [#439](https://github.com/lovell/sharp/pull/439)
+  [@frulo](https://github.com/frulo)
+
+* Allow overlay image to be repeated across entire image via tile option.
+  [#443](https://github.com/lovell/sharp/pull/443)
+  [@lemnisk8](https://github.com/lemnisk8)
+
+* Add cutout option to overlayWith feature, applies only the alpha channel of the overlay image.
+  [#448](https://github.com/lovell/sharp/pull/448)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Ensure scaling factors are calculated independently to prevent rounding errors.
+  [#452](https://github.com/lovell/sharp/issues/452)
+  [@puzrin](https://github.com/puzrin)
+
+* Add --sharp-cxx11 flag to compile with gcc's new C++11 ABI.
+  [#456](https://github.com/lovell/sharp/pull/456)
+  [@kapouer](https://github.com/kapouer)
+
+* Add top/left offset support to overlayWith operation.
+  [#473](https://github.com/lovell/sharp/pull/473)
+  [@rnanwani](https://github.com/rnanwani)
+
+* Add convolve operation for kernel-based convolution.
+  [#479](https://github.com/lovell/sharp/pull/479)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add greyscale option to threshold operation for colourspace conversion control.
+  [#480](https://github.com/lovell/sharp/pull/480)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Ensure ICC profiles are licenced for distribution.
+  [#486](https://github.com/lovell/sharp/issues/486)
+  [@kapouer](https://github.com/kapouer)
+
+* Allow images with an alpha channel to work with LAB-colourspace based sharpen.
+  [#490](https://github.com/lovell/sharp/issues/490)
+  [@jwagner](https://github.com/jwagner)
+
+* Add trim operation to remove "boring" edges.
+  [#492](https://github.com/lovell/sharp/pull/492)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Add bandbool feature for channel-wise boolean operations.
+  [#496](https://github.com/lovell/sharp/pull/496)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add extractChannel operation to extract a channel from an image.
+  [#497](https://github.com/lovell/sharp/pull/497)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add ability to read and write native libvips .v files.
+  [#500](https://github.com/lovell/sharp/pull/500)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add boolean feature for bitwise image operations.
+  [#501](https://github.com/lovell/sharp/pull/501)
+  [@mhirsch](https://github.com/mhirsch)
+
+#### v0.15.0 - 21<sup>st</sup> May 2016
+
+* Use libvips' new Lanczos 3 kernel as default for image reduction.
+  Deprecate interpolateWith method, now provided as a resize option.
+  [#310](https://github.com/lovell/sharp/issues/310)
+  [@jcupitt](https://github.com/jcupitt)
+
+* Take advantage of libvips v8.3 features.
+  Add support for libvips' new GIF and SVG loaders.
+  Pre-built binaries now include giflib and librsvg, exclude *magick.
+  Use shrink-on-load for WebP input.
+  Break existing sharpen API to accept sigma and improve precision.
+  [#369](https://github.com/lovell/sharp/issues/369)
+
+* Remove unnecessary (un)premultiply operations when not resizing/compositing.
+  [#413](https://github.com/lovell/sharp/issues/413)
+  [@jardakotesovec](https://github.com/jardakotesovec)
+
+### v0.14 - "*needle*"
+
+Requires libvips v8.2.3
+
+#### v0.14.1 - 16<sup>th</sup> April 2016
+
+* Allow removal of limitation on input pixel count via limitInputPixels. Use with care.
+  [#250](https://github.com/lovell/sharp/issues/250)
+  [#316](https://github.com/lovell/sharp/pull/316)
+  [@anandthakker](https://github.com/anandthakker)
+  [@kentongray](https://github.com/kentongray)
+
+* Use final output image for metadata passed to callback.
+  [#399](https://github.com/lovell/sharp/pull/399)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Add support for writing tiled images to a zip container.
+  [#402](https://github.com/lovell/sharp/pull/402)
+  [@felixbuenemann](https://github.com/felixbuenemann)
+
+* Allow use of embed with 1 and 2 channel images.
+  [#411](https://github.com/lovell/sharp/issues/411)
+  [@janaz](https://github.com/janaz)
+
+* Improve Electron compatibility by allowing node-gyp rebuilds without npm.
+  [#412](https://github.com/lovell/sharp/issues/412)
+  [@nouh](https://github.com/nouh)
+
+#### v0.14.0 - 2<sup>nd</sup> April 2016
+
+* Add ability to extend (pad) the edges of an image.
+  [#128](https://github.com/lovell/sharp/issues/128)
+  [@blowsie](https://github.com/blowsie)
+
+* Add support for Zoomify and Google tile layouts. Breaks existing tile API.
+  [#223](https://github.com/lovell/sharp/issues/223)
+  [@bdunnette](https://github.com/bdunnette)
+
+* Improvements to overlayWith: differing sizes/formats, gravity, buffer input.
+  [#239](https://github.com/lovell/sharp/issues/239)
+  [@chrisriley](https://github.com/chrisriley)
+
+* Add entropy-based crop strategy to remove least interesting edges.
+  [#295](https://github.com/lovell/sharp/issues/295)
+  [@rightaway](https://github.com/rightaway)
+
+* Expose density metadata; set density of images from vector input.
+  [#338](https://github.com/lovell/sharp/issues/338)
+  [@lookfirst](https://github.com/lookfirst)
+
+* Emit post-processing 'info' event for Stream output.
+  [#367](https://github.com/lovell/sharp/issues/367)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Ensure output image EXIF Orientation values are within 1-8 range.
+  [#385](https://github.com/lovell/sharp/pull/385)
+  [@jtobinisaniceguy](https://github.com/jtobinisaniceguy)
+
+* Ensure ratios are not swapped when rotating 90/270 and ignoring aspect.
+  [#387](https://github.com/lovell/sharp/issues/387)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Remove deprecated style of calling extract API. Breaks calls using positional arguments.
+  [#276](https://github.com/lovell/sharp/issues/276)
+
+### v0.13 - "*mind*"
+
+Requires libvips v8.2.2
+
+#### v0.13.1 - 27<sup>th</sup> February 2016
+
+* Fix embedding onto transparent backgrounds; regression introduced in v0.13.0.
+  [#366](https://github.com/lovell/sharp/issues/366)
+  [@diegocsandrim](https://github.com/diegocsandrim)
+
+#### v0.13.0 - 15<sup>th</sup> February 2016
+
+* Improve vector image support by allowing control of density/DPI.
+  Switch pre-built libs from Imagemagick to Graphicsmagick.
+  [#110](https://github.com/lovell/sharp/issues/110)
+  [@bradisbell](https://github.com/bradisbell)
+
+* Add support for raw, uncompressed pixel Buffer/Stream input.
+  [#220](https://github.com/lovell/sharp/issues/220)
+  [@mikemorris](https://github.com/mikemorris)
+
+* Switch from libvips' C to C++ bindings, requires upgrade to v8.2.2.
+  [#299](https://github.com/lovell/sharp/issues/299)
+
+* Control number of open files in libvips' cache; breaks existing `cache` behaviour.
+  [#315](https://github.com/lovell/sharp/issues/315)
+  [@impomezia](https://github.com/impomezia)
+
+* Ensure 16-bit input images can be normalised and embedded onto transparent backgrounds.
+  [#339](https://github.com/lovell/sharp/issues/339)
+  [#340](https://github.com/lovell/sharp/issues/340)
+  [@janaz](https://github.com/janaz)
+
+* Ensure selected format takes precedence over any unknown output filename extension.
+  [#344](https://github.com/lovell/sharp/issues/344)
+  [@ubaltaci](https://github.com/ubaltaci)
+
+* Add support for libvips' PBM, PGM, PPM and FITS image format loaders.
+  [#347](https://github.com/lovell/sharp/issues/347)
+  [@oaleynik](https://github.com/oaleynik)
+
+* Ensure default crop gravity is center/centre.
+  [#351](https://github.com/lovell/sharp/pull/351)
+  [@joelmukuthu](https://github.com/joelmukuthu)
+
+* Improve support for musl libc systems e.g. Alpine Linux.
+  [#354](https://github.com/lovell/sharp/issues/354)
+  [#359](https://github.com/lovell/sharp/pull/359)
+  [@download13](https://github.com/download13)
+  [@wjordan](https://github.com/wjordan)
+
+* Small optimisation when reducing by an integral factor to favour shrink over affine.
+
+* Add support for gamma correction of images with an alpha channel.
+
+### v0.12 - "*look*"
+
+Requires libvips v8.2.0
+
+#### v0.12.2 - 16<sup>th</sup> January 2016
+
+* Upgrade libvips to v8.2.0 for improved vips_shrink.
+
+* Add pre-compiled libvips for ARMv6+ CPUs.
+
+* Ensure 16-bit input images work with embed option.
+  [#325](https://github.com/lovell/sharp/issues/325)
+  [@janaz](https://github.com/janaz)
+
+* Allow compilation with gmake to provide FreeBSD support.
+  [#326](https://github.com/lovell/sharp/issues/326)
+  [@c0decafe](https://github.com/c0decafe)
+
+* Attempt to remove temporary file after installation.
+  [#331](https://github.com/lovell/sharp/issues/331)
+  [@dtoubelis](https://github.com/dtoubelis)
+
+#### v0.12.1 - 12<sup>th</sup> December 2015
+
+* Allow use of SIMD vector instructions (via liborc) to be toggled on/off.
+  [#172](https://github.com/lovell/sharp/issues/172)
+  [@bkw](https://github.com/bkw)
+  [@puzrin](https://github.com/puzrin)
+
+* Ensure embedded ICC profiles output with perceptual intent.
+  [#321](https://github.com/lovell/sharp/issues/321)
+  [@vlapo](https://github.com/vlapo)
+
+* Use the NPM-configured HTTPS proxy, if any, for binary downloads.
+
+#### v0.12.0 - 23<sup>rd</sup> November 2015
+
+* Bundle pre-compiled libvips and its dependencies for 64-bit Linux and Windows.
+  [#42](https://github.com/lovell/sharp/issues/42)
+
+* Take advantage of libvips v8.1.0+ features.
+  [#152](https://github.com/lovell/sharp/issues/152)
+
+* Add support for 64-bit Windows. Drop support for 32-bit Windows.
+  [#224](https://github.com/lovell/sharp/issues/224)
+  [@sabrehagen](https://github.com/sabrehagen)
+
+* Switch default interpolator to bicubic.
+  [#289](https://github.com/lovell/sharp/issues/289)
+  [@mahnunchik](https://github.com/mahnunchik)
+
+* Pre-extract rotatation should not swap width/height.
+  [#296](https://github.com/lovell/sharp/issues/296)
+  [@asilvas](https://github.com/asilvas)
+
+* Ensure 16-bit+alpha input images are (un)premultiplied correctly.
+  [#301](https://github.com/lovell/sharp/issues/301)
+  [@izaakschroeder](https://github.com/izaakschroeder)
+
+* Add `threshold` operation.
+  [#303](https://github.com/lovell/sharp/pull/303)
+  [@dacarley](https://github.com/dacarley)
+
+* Add `negate` operation.
+  [#306](https://github.com/lovell/sharp/pull/306)
+  [@dacarley](https://github.com/dacarley)
+
+* Support `options` Object with existing `extract` operation.
+  [#309](https://github.com/lovell/sharp/pull/309)
+  [@papandreou](https://github.com/papandreou)
+
+### v0.11 - "*knife*"
+
+#### v0.11.4 - 5<sup>th</sup> November 2015
+
+* Add corners, e.g. `northeast`, to existing `gravity` option.
+  [#291](https://github.com/lovell/sharp/pull/291)
+  [@brandonaaron](https://github.com/brandonaaron)
+
+* Ensure correct auto-rotation for EXIF Orientation values 2 and 4.
+  [#288](https://github.com/lovell/sharp/pull/288)
+  [@brandonaaron](https://github.com/brandonaaron)
+
+* Make static linking possible via `--runtime_link` install option.
+  [#287](https://github.com/lovell/sharp/pull/287)
+  [@vlapo](https://github.com/vlapo)
+
+#### v0.11.3 - 8<sup>th</sup> September 2015
+
+* Intrepret blurSigma, sharpenFlat, and sharpenJagged as double precision.
+  [#263](https://github.com/lovell/sharp/pull/263)
+  [@chrisriley](https://github.com/chrisriley)
+
+#### v0.11.2 - 28<sup>th</sup> August 2015
+
+* Allow crop gravity to be provided as a String.
+  [#255](https://github.com/lovell/sharp/pull/255)
+  [@papandreou](https://github.com/papandreou)
+* Add support for io.js v3 and Node v4.
+  [#246](https://github.com/lovell/sharp/issues/246)
+
+#### v0.11.1 - 12<sup>th</sup> August 2015
+
+* Silence MSVC warning: "C4530: C++ exception handler used, but unwind semantics are not enabled".
+  [#244](https://github.com/lovell/sharp/pull/244)
+  [@TheThing](https://github.com/TheThing)
+
+* Suppress gamma correction for input image with alpha transparency.
+  [#249](https://github.com/lovell/sharp/issues/249)
+  [@compeak](https://github.com/compeak)
+
+#### v0.11.0 - 15<sup>th</sup> July 2015
+
+* Allow alpha transparency compositing via new `overlayWith` method.
+  [#97](https://github.com/lovell/sharp/issues/97)
+  [@gasi](https://github.com/gasi)
+
+* Expose raw ICC profile data as a Buffer when using `metadata`.
+  [#129](https://github.com/lovell/sharp/issues/129)
+  [@homerjam](https://github.com/homerjam)
+
+* Allow image header updates via a parameter passed to existing `withMetadata` method.
+  Provide initial support for EXIF `Orientation` tag,
+  which if present is now removed when using `rotate`, `flip` or `flop`.
+  [#189](https://github.com/lovell/sharp/issues/189)
+  [@h2non](https://github.com/h2non)
+
+* Tighten constructor parameter checks.
+  [#221](https://github.com/lovell/sharp/issues/221)
+  [@mikemorris](https://github.com/mikemorris)
+
+* Allow one input Stream to be shared with two or more output Streams via new `clone` method.
+  [#235](https://github.com/lovell/sharp/issues/235)
+  [@jaubourg](https://github.com/jaubourg)
+
+* Use `round` instead of `floor` when auto-scaling dimensions to avoid floating-point rounding errors.
+  [#238](https://github.com/lovell/sharp/issues/238)
+  [@richardadjogah](https://github.com/richardadjogah)
+
+### v0.10 - "*judgment*"
+
+#### v0.10.1 - 1<sup>st</sup> June 2015
+
+* Allow embed of image with alpha transparency onto non-transparent background.
+  [#204](https://github.com/lovell/sharp/issues/204)
+  [@mikemliu](https://github.com/mikemliu)
+
+* Include C standard library for `atoi` as Xcode 6.3 appears to no longer do this.
+  [#228](https://github.com/lovell/sharp/issues/228)
+  [@doggan](https://github.com/doggan)
+
+#### v0.10.0 - 23<sup>rd</sup> April 2015
+
+* Add support for Windows (x86).
+  [#19](https://github.com/lovell/sharp/issues/19)
+  [@DullReferenceException](https://github.com/DullReferenceException)
+  [@itsananderson](https://github.com/itsananderson)
+
+* Add support for Openslide input and DeepZoom output.
+  [#146](https://github.com/lovell/sharp/issues/146)
+  [@mvictoras](https://github.com/mvictoras)
+
+* Allow arbitrary aspect ratios when resizing images via new `ignoreAspectRatio` method.
+  [#192](https://github.com/lovell/sharp/issues/192)
+  [@skedastik](https://github.com/skedastik)
+
+* Enhance output image contrast by stretching its luminance to cover the full dynamic range via new `normalize` method.
+  [#194](https://github.com/lovell/sharp/issues/194)
+  [@bkw](https://github.com/bkw)
+  [@codingforce](https://github.com/codingforce)

docs/css/extra.css

@@ -0,0 +1,5 @@
+/* Nest document subheadings in navigation */
+ul.subnav ul:not(.subnav) {
+  padding-left: 2em;
+  font-size: 80%;
+}

docs/image/sharp-logo.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="86 86 550 550">
+<!-- Copyright 2019 Lovell Fuller. This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License. -->
+<path fill="none" stroke="#9c0" stroke-width="80" d="M258.411 285.777l200.176-26.8M244.113 466.413L451.44 438.66M451.441 438.66V238.484M451.441 88.363v171.572l178.725-23.917M270.323 255.602V477.22M272.71 634.17V462.591L93.984 486.515"/>
+<path fill="none" stroke="#090" stroke-width="80" d="M451.441 610.246V438.66l178.725-23.91M269.688 112.59v171.58L90.964 308.093"/>
+</svg>

docs/index.md

@@ -0,0 +1,143 @@
+# sharp
+
+<img src="image/sharp-logo.svg" width="160" height="160" alt="sharp logo" align="right">
+
+The typical use case for this high speed Node.js module
+is to convert large images in common formats to
+smaller, web-friendly JPEG, PNG and WebP images of varying dimensions.
+
+Resizing an image is typically 4x-5x faster than using the
+quickest ImageMagick and GraphicsMagick settings.
+
+Colour spaces, embedded ICC profiles and alpha transparency channels are all handled correctly.
+Lanczos resampling ensures quality is not sacrificed for speed.
+
+As well as image resizing, operations such as
+rotation, extraction, compositing and gamma correction are available.
+
+Most modern 64-bit OS X, Windows and Linux systems running
+Node versions 6, 8 and 10
+do not require any additional install or runtime dependencies.
+
+[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.png?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
+
+### Formats
+
+This module supports reading JPEG, PNG, WebP, TIFF, GIF and SVG images.
+
+Output images can be in JPEG, PNG, WebP and TIFF formats as well as uncompressed raw pixel data.
+
+Streams, Buffer objects and the filesystem can be used for input and output.
+
+A single input Stream can be split into multiple processing pipelines and output Streams.
+
+Deep Zoom image pyramids can be generated,
+suitable for use with "slippy map" tile viewers like
+[OpenSeadragon](https://github.com/openseadragon/openseadragon)
+and [Leaflet](https://github.com/turban/Leaflet.Zoomify).
+
+### Fast
+
+This module is powered by the blazingly fast
+[libvips](https://github.com/libvips/libvips) image processing library,
+originally created in 1989 at Birkbeck College
+and currently maintained by
+[John Cupitt](https://github.com/jcupitt).
+
+Only small regions of uncompressed image data
+are held in memory and processed at a time,
+taking full advantage of multiple CPU cores and L1/L2/L3 cache.
+
+Everything remains non-blocking thanks to _libuv_,
+no child processes are spawned and Promises/async/await are supported.
+
+### Optimal
+
+Huffman tables are optimised when generating JPEG output images
+without having to use separate command line tools like
+[jpegoptim](https://github.com/tjko/jpegoptim) and
+[jpegtran](http://jpegclub.org/jpegtran/).
+
+PNG filtering is disabled by default,
+which for diagrams and line art often produces the same result
+as [pngcrush](https://pmt.sourceforge.io/pngcrush/).
+
+### Contributing
+
+A [guide for contributors](https://github.com/lovell/sharp/blob/master/CONTRIBUTING.md)
+covers reporting bugs, requesting features and submitting code changes.
+
+### Credits
+
+This module would never have been possible without
+the help and code contributions of the following people:
+
+* [John Cupitt](https://github.com/jcupitt)
+* [Pierre Inglebert](https://github.com/pierreinglebert)
+* [Jonathan Ong](https://github.com/jonathanong)
+* [Chanon Sajjamanochai](https://github.com/chanon)
+* [Juliano Julio](https://github.com/julianojulio)
+* [Daniel Gasienica](https://github.com/gasi)
+* [Julian Walker](https://github.com/julianwa)
+* [Amit Pitaru](https://github.com/apitaru)
+* [Brandon Aaron](https://github.com/brandonaaron)
+* [Andreas Lind](https://github.com/papandreou)
+* [Maurus Cuelenaere](https://github.com/mcuelenaere)
+* [Linus Unnebäck](https://github.com/LinusU)
+* [Victor Mateevitsi](https://github.com/mvictoras)
+* [Alaric Holloway](https://github.com/skedastik)
+* [Bernhard K. Weisshuhn](https://github.com/bkw)
+* [David A. Carley](https://github.com/dacarley)
+* [John Tobin](https://github.com/jtobinisaniceguy)
+* [Kenton Gray](https://github.com/kentongray)
+* [Felix Bünemann](https://github.com/felixbuenemann)
+* [Samy Al Zahrani](https://github.com/salzhrani)
+* [Chintan Thakkar](https://github.com/lemnisk8)
+* [F. Orlando Galashan](https://github.com/frulo)
+* [Kleis Auke Wolthuizen](https://github.com/kleisauke)
+* [Matt Hirsch](https://github.com/mhirsch)
+* [Rahul Nanwani](https://github.com/rnanwani)
+* [Matthias Thoemmes](https://github.com/cmtt)
+* [Patrick Paskaris](https://github.com/ppaskaris)
+* [Jérémy Lal](https://github.com/kapouer)
+* [Alice Monday](https://github.com/alice0meta)
+* [Kristo Jorgenson](https://github.com/kristojorg)
+* [Yves Bos](https://github.com/YvesBos)
+* [Nicolas Coden](https://github.com/ncoden)
+* [Matt Parrish](https://github.com/pbomb)
+* [Matthew McEachen](https://github.com/mceachen)
+* [Jarda Kotěšovec](https://github.com/jardakotesovec)
+* [Kenric D'Souza](https://github.com/AzureByte)
+* [Oleh Aleinyk](https://github.com/oaleynik)
+* [Marcel Bretschneider](https://github.com/3epnm)
+* [Andrea Bianco](https://github.com/BiancoA)
+* [Rik Heywood](https://github.com/rikh42)
+* [Thomas Parisot](https://github.com/oncletom)
+* [Nathan Graves](https://github.com/woolite64)
+* [Tom Lokhorst](https://github.com/tomlokhorst)
+* [Espen Hovlandsdal](https://github.com/rexxars)
+* [Sylvain Dumont](https://github.com/sylvaindumont)
+* [Alun Davies](https://github.com/alundavies)
+* [Aidan Hoolachan](https://github.com/ajhool)
+* [Axel Eirola](https://github.com/aeirola)
+* [Freezy](https://github.com/freezy)
+* [Julian Aubourg](https://github.com/jaubourg)
+* [Keith Belovay](https://github.com/fromkeith)
+* [Michael B. Klein](https://github.com/mbklein)
+
+Thank you!
+
+### Licensing
+
+Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+[https://www.apache.org/licenses/LICENSE-2.0](https://www.apache.org/licenses/LICENSE-2.0)
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

docs/install.md

@@ -0,0 +1,285 @@
+# Installation
+
+```sh
+npm install sharp
+```
+
+```sh
+yarn add sharp
+```
+
+## Prerequisites
+
+* Node v4.5.0+
+
+### Building from source
+
+Pre-compiled binaries for sharp are provided for use with
+Node versions 6, 8, 10 and 11 on
+64-bit Windows, OS X and Linux platforms.
+
+Sharp will be built from source at install time when:
+
+* a globally-installed libvips is detected,
+* pre-compiled binaries do not exist for the current platform and Node version, or
+* when the `npm install --build-from-source` flag is used.
+
+Building from source requires:
+
+* C++11 compatible compiler such as gcc 4.8+, clang 3.0+ or MSVC 2013+
+* [node-gyp](https://github.com/nodejs/node-gyp#installation) and its dependencies (includes Python 2.7)
+
+## libvips
+
+### Linux
+
+[![Ubuntu 16.04 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+
+libvips and its dependencies are fetched and stored within `node_modules/sharp/vendor` during `npm install`.
+This involves an automated HTTPS download of approximately 9MB.
+
+Most Linux-based (glibc, musl) operating systems running on x64 and ARMv6+ CPUs should "just work", e.g.:
+
+* Debian 7+
+* Ubuntu 14.04+
+* Centos 7+
+* Alpine 3.8+ (Node 8 and 10)
+* Fedora
+* openSUSE 13.2+
+* Archlinux
+* Raspbian Jessie
+* Amazon Linux
+* Solus
+
+To use a globally-installed version of libvips instead of the provided binaries,
+make sure it is at least the version listed under `config.libvips` in the `package.json` file
+and that it can be located using `pkg-config --modversion vips-cpp`.
+
+If you are using non-standard paths (anything other than `/usr` or `/usr/local`),
+you might need to set `PKG_CONFIG_PATH` during `npm install`
+and `LD_LIBRARY_PATH` at runtime.
+
+This allows the use of newer versions of libvips with older versions of sharp.
+
+For 32-bit Intel CPUs and older Linux-based operating systems such as Centos 6,
+compiling libvips from source is recommended.
+
+[https://libvips.github.io/libvips/install.html#building-libvips-from-a-source-tarball](https://libvips.github.io/libvips/install.html#building-libvips-from-a-source-tarball)
+
+#### Alpine Linux
+
+libvips is available in the
+[testing repository](https://pkgs.alpinelinux.org/packages?name=vips-dev):
+
+```sh
+apk add vips-dev fftw-dev build-base --update-cache \
+    --repository https://alpine.global.ssl.fastly.net/alpine/edge/testing/ \
+    --repository https://alpine.global.ssl.fastly.net/alpine/edge/main
+```
+
+The smaller stack size of musl libc means
+libvips may need to be used without a cache
+via `sharp.cache(false)` to avoid a stack overflow.
+
+### Mac OS
+
+[![OS X 10.12 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+
+libvips and its dependencies are fetched and stored within `node_modules/sharp/vendor` during `npm install`.
+This involves an automated HTTPS download of approximately 8MB.
+
+To use your own version of libvips instead of the provided binaries, make sure it is
+at least the version listed under `config.libvips` in the `package.json` file and
+that it can be located using `pkg-config --modversion vips-cpp`.
+
+### Windows x64
+
+[![Windows x64 Build Status](https://ci.appveyor.com/api/projects/status/pgtul704nkhhg6sg)](https://ci.appveyor.com/project/lovell/sharp)
+
+libvips and its dependencies are fetched and stored within `node_modules\sharp\vendor` during `npm install`.
+This involves an automated HTTPS download of approximately 14MB.
+If you are having issues during installation consider removing the directory
+`C:\Users\[user]\AppData\Roaming\npm-cache\_libvips`.
+
+Only 64-bit (x64) `node.exe` is supported.
+
+### FreeBSD
+
+libvips must be installed before `npm install` is run.
+
+This can be achieved via package or ports:
+
+```sh
+pkg install -y pkgconf vips
+```
+
+```sh
+cd /usr/ports/graphics/vips/ && make install clean
+```
+
+FreeBSD's gcc v4 and v5 need `CXXFLAGS=-D_GLIBCXX_USE_C99` set for C++11 support due to
+https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193528
+
+### Heroku
+
+Set [NODE_MODULES_CACHE](https://devcenter.heroku.com/articles/nodejs-support#cache-behavior)
+to `false` when using the `yarn` package manager.
+
+### Docker
+
+[Marc Bachmann](https://github.com/marcbachmann) maintains an
+[Ubuntu-based Dockerfile for libvips](https://github.com/marcbachmann/dockerfile-libvips).
+
+```sh
+docker pull marcbachmann/libvips
+```
+
+[Will Jordan](https://github.com/wjordan) maintains an
+[Alpine-based Dockerfile for libvips](https://github.com/wjordan/dockerfile-libvips).
+
+```sh
+docker pull wjordan/libvips
+```
+
+[Tailor Brands](https://github.com/TailorBrands) maintain
+[Debian-based Dockerfiles for libvips and nodejs](https://github.com/TailorBrands/docker-libvips).
+
+```sh
+docker pull tailor/docker-libvips
+```
+
+### AWS Lambda
+
+Set the Lambda runtime to Node.js 8.10.
+
+The binaries in the `node_modules` directory of the
+[deployment package](https://docs.aws.amazon.com/lambda/latest/dg/nodejs-create-deployment-pkg.html)
+must be for the Linux x64 platform/architecture.
+
+On non-Linux machines such as OS X and Windows run the following:
+
+```sh
+rm -rf node_modules/sharp
+npm install --arch=x64 --platform=linux --target=8.10.0 sharp
+```
+
+Alternatively a Docker container closely matching the Lambda runtime can be used:
+
+```sh
+rm -rf node_modules/sharp
+docker run -v "$PWD":/var/task lambci/lambda:build-nodejs8.10 npm install sharp
+```
+
+To get the best performance select the largest memory available.
+A 1536 MB function provides ~12x more CPU time than a 128 MB function.
+
+### NW.js
+
+Run the `nw-gyp` tool after installation.
+
+```sh
+cd node-modules/sharp
+nw-gyp rebuild --arch=x64 --target=[your nw version]
+node node_modules/sharp/install/dll-copy
+```
+
+[http://docs.nwjs.io/en/latest/For%20Users/Advanced/Use%20Native%20Node%20Modules/](http://docs.nwjs.io/en/latest/For%20Users/Advanced/Use%20Native%20Node%20Modules/)
+
+### Build tools
+
+* [gulp-responsive](https://www.npmjs.com/package/gulp-responsive)
+* [grunt-sharp](https://www.npmjs.com/package/grunt-sharp)
+
+### Coding tools
+
+* [Sharp TypeScript Types](https://www.npmjs.com/package/@types/sharp)
+
+### CLI tools
+
+* [sharp-cli](https://www.npmjs.com/package/sharp-cli)
+
+### Security
+
+Many users of this module process untrusted, user-supplied images,
+but there are aspects of security to consider when doing so.
+
+It is possible to compile libvips with support for various third-party image loaders.
+Each of these libraries has undergone differing levels of security testing.
+
+Whilst tools such as [American Fuzzy Lop](http://lcamtuf.coredump.cx/afl/)
+and [Valgrind](http://valgrind.org/) have been used to test
+the most popular web-based formats, as well as libvips itself,
+you are advised to perform your own testing and sandboxing.
+
+### Pre-compiled libvips binaries
+
+This module will attempt to download a pre-compiled bundle of libvips
+and its dependencies on Linux and Windows machines under either of these
+conditions:
+
+1. If a global installation of libvips that meets the
+minimum version requirement cannot be found;
+1. If `SHARP_IGNORE_GLOBAL_LIBVIPS` environment variable is set.
+
+```sh
+SHARP_IGNORE_GLOBAL_LIBVIPS=1 npm install sharp
+```
+
+Should you need to manually download and inspect these files,
+you can do so via
+[https://github.com/lovell/sharp-libvips/releases](https://github.com/lovell/sharp-libvips/releases)
+
+Should you wish to install these from your own location,
+set the `sharp_dist_base_url` npm config option, e.g.
+
+```sh
+npm config set sharp_dist_base_url "https://hostname/path/"
+npm install sharp
+```
+
+or set the `SHARP_DIST_BASE_URL` environment variable, e.g.
+
+```sh
+SHARP_DIST_BASE_URL="https://hostname/path/" npm install sharp
+```
+
+to use `https://hostname/path/libvips-x.y.z-platform.tar.gz`.
+
+### Licences
+
+This module is licensed under the terms of the
+[Apache 2.0 Licence](https://github.com/lovell/sharp/blob/master/LICENSE).
+
+The libraries downloaded and used by this module
+are done so under the terms of the following licences,
+all of which are compatible with the Apache 2.0 Licence.
+
+Use of libraries under the terms of the LGPLv3 is via the
+"any later version" clause of the LGPLv2 or LGPLv2.1.
+
+| Library       | Used under the terms of                                                                                  |
+|---------------|----------------------------------------------------------------------------------------------------------|
+| cairo         | Mozilla Public License 2.0                                                                               |
+| expat         | MIT Licence                                                                                              |
+| fontconfig    | [fontconfig Licence](https://cgit.freedesktop.org/fontconfig/tree/COPYING) (BSD-like)                    |
+| freetype      | [freetype Licence](http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/docs/FTL.TXT) (BSD-like) |
+| fribidi       | LGPLv3                                                                                                   |
+| gettext       | LGPLv3                                                                                                   |
+| giflib        | MIT Licence                                                                                              |
+| glib          | LGPLv3                                                                                                   |
+| harfbuzz      | MIT Licence                                                                                              |
+| lcms          | MIT Licence                                                                                              |
+| libcroco      | LGPLv3                                                                                                   |
+| libexif       | LGPLv3                                                                                                   |
+| libffi        | MIT Licence                                                                                              |
+| libgsf        | LGPLv3                                                                                                   |
+| libjpeg-turbo | [zlib License, IJG License](https://github.com/libjpeg-turbo/libjpeg-turbo/blob/master/LICENSE.md)       |
+| libpng        | [libpng License](http://www.libpng.org/pub/png/src/libpng-LICENSE.txt)                                   |
+| librsvg       | LGPLv3                                                                                                   |
+| libtiff       | [libtiff License](http://www.libtiff.org/misc.html) (BSD-like)                                           |
+| libvips       | LGPLv3                                                                                                   |
+| libwebp       | New BSD License                                                                                          |
+| libxml2       | MIT Licence                                                                                              |
+| pango         | LGPLv3                                                                                                   |
+| pixman        | MIT Licence                                                                                              |
+| zlib          | [zlib Licence](https://github.com/madler/zlib/blob/master/zlib.h)                                        |

docs/performance.md

@@ -0,0 +1,69 @@
+# Performance
+
+### Test environment
+
+* AWS EC2 eu-west-1 [c5.large](https://aws.amazon.com/ec2/instance-types/c5/) (2x Xeon Platinum 8124M CPU @ 3.00GHz)
+* Ubuntu 18.04 (hvm-ssd/ubuntu-bionic-18.04-amd64-server-20180912 ami-00035f41c82244dab)
+* Node.js v10.11.0
+
+### The contenders
+
+* [jimp](https://www.npmjs.com/package/jimp) v0.5.3 - Image processing in pure JavaScript. Provides bicubic interpolation.
+* [mapnik](https://www.npmjs.org/package/mapnik) v4.0.1 - Whilst primarily a map renderer, Mapnik contains bitmap image utilities.
+* [imagemagick-native](https://www.npmjs.com/package/imagemagick-native) v1.9.3 - Wrapper around libmagick++, supports Buffers only.
+* [imagemagick](https://www.npmjs.com/package/imagemagick) v0.1.3 - Supports filesystem only and "*has been unmaintained for a long time*".
+* [gm](https://www.npmjs.com/package/gm) v1.23.1 - Fully featured wrapper around GraphicsMagick's `gm` command line utility.
+* sharp v0.21.0 / libvips v8.7.0 - Caching within libvips disabled to ensure a fair comparison.
+
+### The task
+
+Decompress a 2725x2225 JPEG image,
+resize to 720x588 using Lanczos 3 resampling (where available),
+then compress to JPEG at a "quality" setting of 80.
+
+### Results
+
+| Module             | Input  | Output | Ops/sec | Speed-up |
+| :----------------- | :----- | :----- | ------: | -------: |
+| jimp               | buffer | buffer |    0.71 |      1.0 |
+| mapnik             | buffer | buffer |    3.32 |      4.7 |
+| gm                 | buffer | buffer |    3.97 |      5.6 |
+| imagemagick-native | buffer | buffer |    4.06 |      5.7 |
+| imagemagick        | file   | file   |    4.24 |      6.0 |
+| sharp              | stream | stream |   25.30 |     35.6 |
+| sharp              | file   | file   |   26.17 |     36.9 |
+| sharp              | buffer | buffer |   26.45 |     37.3 |
+
+Greater libvips performance can be expected with caching enabled (default)
+and using 8+ core machines, especially those with larger L1/L2 CPU caches.
+
+The I/O limits of the relevant (de)compression library will generally determine maximum throughput.
+
+### Benchmark test prerequisites
+
+Requires _ImageMagick_, _GraphicsMagick_ and _Mapnik_:
+
+```sh
+brew install imagemagick
+brew install graphicsmagick
+brew install mapnik
+```
+
+```sh
+sudo apt-get install imagemagick libmagick++-dev graphicsmagick libmapnik-dev
+```
+
+```sh
+sudo yum install ImageMagick-devel ImageMagick-c++-devel GraphicsMagick mapnik-devel
+```
+
+### Running the benchmark test
+
+```sh
+git clone https://github.com/lovell/sharp.git
+cd sharp
+npm install
+cd test/bench
+npm install
+npm test
+```

index.js

@@ -1,588 +0,0 @@
-'use strict';
-
-var path = require('path');
-var util = require('util');
-var stream = require('stream');
-
-var semver = require('semver');
-var color = require('color');
-var BluebirdPromise = require('bluebird');
-
-var sharp = require('./build/Release/sharp');
-var libvipsVersion = sharp.libvipsVersion();
-
-var Sharp = function(input) {
-  if (!(this instanceof Sharp)) {
-    return new Sharp(input);
-  }
-  stream.Duplex.call(this);
-  this.options = {
-    // input options
-    streamIn: false,
-    sequentialRead: false,
-    // ICC profile to use when input CMYK image has no embedded profile
-    iccProfileCmyk: path.join(__dirname, 'icc', 'USWebCoatedSWOP.icc'),
-    // resize options
-    topOffsetPre: -1,
-    leftOffsetPre: -1,
-    widthPre: -1,
-    heightPre: -1,
-    topOffsetPost: -1,
-    leftOffsetPost: -1,
-    widthPost: -1,
-    heightPost: -1,
-    width: -1,
-    height: -1,
-    canvas: 'c',
-    gravity: 0,
-    angle: 0,
-    flip: false,
-    flop: false,
-    withoutEnlargement: false,
-    interpolator: 'bilinear',
-    // operations
-    background: [0, 0, 0, 255],
-    flatten: false,
-    blurRadius: 0,
-    sharpenRadius: 0,
-    sharpenFlat: 1,
-    sharpenJagged: 2,
-    gamma: 0,
-    greyscale: false,
-    // output options
-    output: '__input',
-    progressive: false,
-    quality: 80,
-    compressionLevel: 6,
-    withoutAdaptiveFiltering: false,
-    streamOut: false,
-    withMetadata: false
-  };
-  if (typeof input === 'string') {
-    // input=file
-    this.options.fileIn = input;
-  } else if (typeof input === 'object' && input instanceof Buffer) {
-    // input=buffer
-    if (
-      (input.length > 3) &&
-      // JPEG
-      (input[0] === 0xFF && input[1] === 0xD8) ||
-      // PNG
-      (input[0] === 0x89 && input[1] === 0x50) ||
-      // WebP
-      (input[0] === 0x52 && input[1] === 0x49) ||
-      // TIFF
-      (input[0] === 0x4D && input[1] === 0x4D && input[2] === 0x00 && (input[3] === 0x2A || input[3] === 0x2B)) ||
-      (input[0] === 0x49 && input[1] === 0x49 && (input[2] === 0x2A || input[2] === 0x2B) && input[3] === 0x00)
-    ) {
-      this.options.bufferIn = input;
-    } else {
-      throw new Error('Buffer contains an unsupported image format. JPEG, PNG, WebP and TIFF are currently supported.');
-    }
-  } else {
-    // input=stream
-    this.options.streamIn = true;
-  }
-  return this;
-};
-module.exports = Sharp;
-util.inherits(Sharp, stream.Duplex);
-
-/*
-  Handle incoming chunk on Writable Stream
-*/
-Sharp.prototype._write = function(chunk, encoding, callback) {
-  /*jslint unused: false */
-  if (this.options.streamIn) {
-    if (typeof chunk === 'object' && chunk instanceof Buffer) {
-      if (typeof this.options.bufferIn === 'undefined') {
-        // Create new Buffer
-        this.options.bufferIn = new Buffer(chunk.length);
-        chunk.copy(this.options.bufferIn);
-      } else {
-        // Append to existing Buffer
-        this.options.bufferIn = Buffer.concat(
-          [this.options.bufferIn, chunk],
-          this.options.bufferIn.length + chunk.length
-        );
-      }
-      callback();
-    } else {
-      callback(new Error('Non-Buffer data on Writable Stream'));
-    }
-  } else {
-    callback(new Error('Unexpected data on Writable Stream'));
-  }
-};
-
-// Crop this part of the resized image (Center/Centre, North, East, South, West)
-module.exports.gravity = {'center': 0, 'centre': 0, 'north': 1, 'east': 2, 'south': 3, 'west': 4};
-
-Sharp.prototype.crop = function(gravity) {
-  this.options.canvas = 'c';
-  if (typeof gravity === 'number' && !Number.isNaN(gravity) && gravity >= 0 && gravity <= 4) {
-    this.options.gravity = gravity;
-  } else {
-    throw new Error('Unsupported crop gravity ' + gravity);
-  }
-  return this;
-};
-
-Sharp.prototype.extract = function(topOffset, leftOffset, width, height) {
-  /*jslint unused: false */
-  var suffix = this.options.width === -1 && this.options.height === -1 ? 'Pre' : 'Post';
-  var values = arguments;
-  ['topOffset', 'leftOffset', 'width', 'height'].forEach(function(name, index) {
-    this.options[name + suffix] = values[index];
-  }.bind(this));
-  return this;
-};
-
-/*
-  Set the background colour for embed and flatten operations.
-  Delegates to the 'Color' module, which can throw an Error
-  but is liberal in what it accepts, clamping values to sensible min/max.
-*/
-Sharp.prototype.background = function(rgba) {
-  var colour = color(rgba);
-  this.options.background = colour.rgbArray();
-  this.options.background.push(colour.alpha() * 255);
-  return this;
-};
-
-Sharp.prototype.embed = function() {
-  this.options.canvas = 'e';
-  return this;
-};
-
-Sharp.prototype.max = function() {
-  this.options.canvas = 'm';
-  return this;
-};
-
-Sharp.prototype.flatten = function(flatten) {
-  this.options.flatten = (typeof flatten === 'boolean') ? flatten : true;
-  return this;
-};
-
-/*
-  Rotate output image by 0, 90, 180 or 270 degrees
-  Auto-rotation based on the EXIF Orientation tag is represented by an angle of -1
-*/
-Sharp.prototype.rotate = function(angle) {
-  if (typeof angle === 'undefined') {
-    this.options.angle = -1;
-  } else if (!Number.isNaN(angle) && [0, 90, 180, 270].indexOf(angle) !== -1) {
-    this.options.angle = angle;
-  } else {
-    throw new Error('Unsupported angle (0, 90, 180, 270) ' + angle);
-  }
-  return this;
-};
-
-/*
-  Flip the image vertically, about the Y axis
-*/
-Sharp.prototype.flip = function(flip) {
-  this.options.flip = (typeof flip === 'boolean') ? flip : true;
-  return this;
-};
-
-/*
-  Flop the image horizontally, about the X axis
-*/
-Sharp.prototype.flop = function(flop) {
-  this.options.flop = (typeof flop === 'boolean') ? flop : true;
-  return this;
-};
-
-/*
-  Do not enlarge the output if the input width *or* height are already less than the required dimensions
-  This is equivalent to GraphicsMagick's ">" geometry option:
-    "change the dimensions of the image only if its width or height exceeds the geometry specification"
-*/
-Sharp.prototype.withoutEnlargement = function(withoutEnlargement) {
-  this.options.withoutEnlargement = (typeof withoutEnlargement === 'boolean') ? withoutEnlargement : true;
-  return this;
-};
-
-/*
-  Blur the output image.
-  Call without a radius to use a fast, mild blur.
-  Call with a radius to use a slower, more accurate Gaussian blur.
-*/
-Sharp.prototype.blur = function(radius) {
-  if (typeof radius === 'undefined') {
-    // No arguments: default to mild blur
-    this.options.blurRadius = -1;
-  } else if (typeof radius === 'boolean') {
-    // Boolean argument: apply mild blur?
-    this.options.blurRadius = radius ? -1 : 0;
-  } else if (typeof radius === 'number' && !Number.isNaN(radius) && (radius % 1 === 0) && radius >= 1) {
-    // Numeric argument: specific radius
-    this.options.blurRadius = radius;
-  } else {
-    throw new Error('Invalid blur radius ' + radius + ' (expected integer >= 1)');
-  }
-  return this;
-};
-
-/*
-  Sharpen the output image.
-  Call without a radius to use a fast, mild sharpen.
-  Call with a radius to use a slow, accurate sharpen using the L of LAB colour space.
-    radius - size of mask in pixels, must be integer
-    flat - level of "flat" area sharpen, default 1
-    jagged - level of "jagged" area sharpen, default 2
-*/
-Sharp.prototype.sharpen = function(radius, flat, jagged) {
-  if (typeof radius === 'undefined') {
-    // No arguments: default to mild sharpen
-    this.options.sharpenRadius = -1;
-  } else if (typeof radius === 'boolean') {
-    // Boolean argument: apply mild sharpen?
-    this.options.sharpenRadius = radius ? -1 : 0;
-  } else if (typeof radius === 'number' && !Number.isNaN(radius) && (radius % 1 === 0) && radius >= 1) {
-    // Numeric argument: specific radius
-    this.options.sharpenRadius = radius;
-    // Control over flat areas
-    if (typeof flat !== 'undefined' && flat !== null) {
-      if (typeof flat === 'number' && !Number.isNaN(flat) && flat >= 0) {
-        this.options.sharpenFlat = flat;
-      } else {
-        throw new Error('Invalid sharpen level for flat areas ' + flat + ' (expected >= 0)');
-      }
-    }
-    // Control over jagged areas
-    if (typeof jagged !== 'undefined' && jagged !== null) {
-      if (typeof jagged === 'number' && !Number.isNaN(jagged) && jagged >= 0) {
-        this.options.sharpenJagged = jagged;
-      } else {
-        throw new Error('Invalid sharpen level for jagged areas ' + jagged + ' (expected >= 0)');
-      }
-    }
-  } else {
-    throw new Error('Invalid sharpen radius ' + radius + ' (expected integer >= 1)');
-  }
-  return this;
-};
-
-/*
-  Set the interpolator to use for the affine transformation
-*/
-module.exports.interpolator = {
-  nearest: 'nearest',
-  bilinear: 'bilinear',
-  bicubic: 'bicubic',
-  nohalo: 'nohalo',
-  locallyBoundedBicubic: 'lbb',
-  vertexSplitQuadraticBasisSpline: 'vsqbs'
-};
-Sharp.prototype.interpolateWith = function(interpolator) {
-  this.options.interpolator = interpolator;
-  return this;
-};
-
-/*
-  Darken image pre-resize (1/gamma) and brighten post-resize (gamma).
-  Improves brightness of resized image in non-linear colour spaces.
-*/
-Sharp.prototype.gamma = function(gamma) {
-  if (typeof gamma === 'undefined') {
-    // Default gamma correction of 2.2 (sRGB)
-    this.options.gamma = 2.2;
-  } else if (!Number.isNaN(gamma) && gamma >= 1 && gamma <= 3) {
-    this.options.gamma = gamma;
-  } else {
-    throw new Error('Invalid gamma correction (1.0 to 3.0) ' + gamma);
-  }
-  return this;
-};
-
-/*
-  Convert to greyscale
-*/
-Sharp.prototype.greyscale = function(greyscale) {
-  this.options.greyscale = (typeof greyscale === 'boolean') ? greyscale : true;
-  return this;
-};
-Sharp.prototype.grayscale = Sharp.prototype.greyscale;
-
-Sharp.prototype.progressive = function(progressive) {
-  this.options.progressive = (typeof progressive === 'boolean') ? progressive : true;
-  return this;
-};
-
-Sharp.prototype.sequentialRead = function(sequentialRead) {
-  this.options.sequentialRead = (typeof sequentialRead === 'boolean') ? sequentialRead : true;
-  return this;
-};
-
-Sharp.prototype.quality = function(quality) {
-  if (!Number.isNaN(quality) && quality >= 1 && quality <= 100) {
-    this.options.quality = quality;
-  } else {
-    throw new Error('Invalid quality (1 to 100) ' + quality);
-  }
-  return this;
-};
-
-/*
-  zlib compression level for PNG output
-*/
-Sharp.prototype.compressionLevel = function(compressionLevel) {
-  if (!Number.isNaN(compressionLevel) && compressionLevel >= 0 && compressionLevel <= 9) {
-    this.options.compressionLevel = compressionLevel;
-  } else {
-    throw new Error('Invalid compressionLevel (0 to 9) ' + compressionLevel);
-  }
-  return this;
-};
-
-/*
-  Disable the use of adaptive row filtering for PNG output - requires libvips 7.41.0+
-*/
-Sharp.prototype.withoutAdaptiveFiltering = function(withoutAdaptiveFiltering) {
-  if (semver.gte(libvipsVersion, '7.41.0')) {
-    this.options.withoutAdaptiveFiltering = (typeof withoutAdaptiveFiltering === 'boolean') ? withoutAdaptiveFiltering : true;
-  } else {
-    console.error('withoutAdaptiveFiltering requires libvips 7.41.0+');
-  }
-  return this;
-};
-
-Sharp.prototype.withMetadata = function(withMetadata) {
-  this.options.withMetadata = (typeof withMetadata === 'boolean') ? withMetadata : true;
-  return this;
-};
-
-Sharp.prototype.resize = function(width, height) {
-  if (!width) {
-    this.options.width = -1;
-  } else {
-    if (typeof width === 'number' && !Number.isNaN(width)) {
-      this.options.width = width;
-    } else {
-      throw new Error('Invalid width ' + width);
-    }
-  }
-  if (!height) {
-    this.options.height = -1;
-  } else {
-    if (typeof height === 'number' && !Number.isNaN(height)) {
-      this.options.height = height;
-    } else {
-      throw new Error('Invalid height ' + height);
-    }
-  }
-  return this;
-};
-
-/*
-  Write output image data to a file
-*/
-Sharp.prototype.toFile = function(output, callback) {
-  if (!output || output.length === 0) {
-    var errOutputInvalid = new Error('Invalid output');
-    if (typeof callback === 'function') {
-      callback(errOutputInvalid);
-    } else {
-      return BluebirdPromise.reject(errOutputInvalid);
-    }
-  } else {
-    if (this.options.fileIn === output) {
-      var errOutputIsInput = new Error('Cannot use same file for input and output');
-      if (typeof callback === 'function') {
-        callback(errOutputIsInput);
-      } else {
-        return BluebirdPromise.reject(errOutputIsInput);
-      }
-    } else {
-      this.options.output = output;
-      return this._sharp(callback);
-    }
-  }
-  return this;
-};
-
-Sharp.prototype.toBuffer = function(callback) {
-  return this._sharp(callback);
-};
-
-Sharp.prototype.jpeg = function() {
-  this.options.output = '__jpeg';
-  return this;
-};
-
-Sharp.prototype.png = function() {
-  this.options.output = '__png';
-  return this;
-};
-
-Sharp.prototype.webp = function() {
-  this.options.output = '__webp';
-  return this;
-};
-
-/*
-  Used by a Writable Stream to notify that it is ready for data
-*/
-Sharp.prototype._read = function() {
-  if (!this.options.streamOut) {
-    this.options.streamOut = true;
-    this._sharp();
-  }
-};
-
-/*
-  Invoke the C++ image processing pipeline
-  Supports callback, stream and promise variants
-*/
-Sharp.prototype._sharp = function(callback) {
-  var that = this;
-  if (typeof callback === 'function') {
-    // output=file/buffer
-    if (this.options.streamIn) {
-      // output=file/buffer, input=stream
-      this.on('finish', function() {
-        sharp.resize(that.options, callback);
-      });
-    } else {
-      // output=file/buffer, input=file/buffer
-      sharp.resize(this.options, callback);
-    }
-    return this;
-  } else if (this.options.streamOut) {
-    // output=stream
-    if (this.options.streamIn) {
-      // output=stream, input=stream
-      this.on('finish', function() {
-        sharp.resize(that.options, function(err, data) {
-          if (err) {
-            that.emit('error', new Error(err));
-          } else {
-            that.push(data);
-          }
-          that.push(null);
-        });
-      });
-    } else {
-      // output=stream, input=file/buffer
-      sharp.resize(this.options, function(err, data) {
-        if (err) {
-          that.emit('error', new Error(err));
-        } else {
-          that.push(data);
-        }
-        that.push(null);
-      });
-    }
-    return this;
-  } else {
-    // output=promise
-    if (this.options.streamIn) {
-      // output=promise, input=stream
-      return new BluebirdPromise(function(resolve, reject) {
-        that.on('finish', function() {
-          sharp.resize(that.options, function(err, data) {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(data);
-            }
-          });
-        });
-      });
-    } else {
-      // output=promise, input=file/buffer
-      return new BluebirdPromise(function(resolve, reject) {
-        sharp.resize(that.options, function(err, data) {
-          if (err) {
-            reject(err);
-          } else {
-            resolve(data);
-          }
-        });
-      });
-    }
-  }
-};
-
-/*
-  Reads the image header and returns metadata
-  Supports callback, stream and promise variants
-*/
-Sharp.prototype.metadata = function(callback) {
-  var that = this;
-  if (typeof callback === 'function') {
-    if (this.options.streamIn) {
-      this.on('finish', function() {
-        sharp.metadata(that.options, callback);
-      });
-    } else {
-      sharp.metadata(this.options, callback);
-    }
-    return this;
-  } else {
-    if (this.options.streamIn) {
-      return new BluebirdPromise(function(resolve, reject) {
-        that.on('finish', function() {
-          sharp.metadata(that.options, function(err, data) {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(data);
-            }
-          });
-        });
-      });
-    } else {
-      return new BluebirdPromise(function(resolve, reject) {
-        sharp.metadata(that.options, function(err, data) {
-          if (err) {
-            reject(err);
-          } else {
-            resolve(data);
-          }
-        });
-      });
-    }
-  }
-};
-
-/*
-  Get and set cache memory and item limits
-*/
-module.exports.cache = function(memory, items) {
-  if (typeof memory !== 'number' || Number.isNaN(memory)) {
-    memory = null;
-  }
-  if (typeof items !== 'number' || Number.isNaN(items)) {
-    items = null;
-  }
-  return sharp.cache(memory, items);
-};
-
-/*
-  Get and set size of thread pool
-*/
-module.exports.concurrency = function(concurrency) {
-  if (typeof concurrency !== 'number' || Number.isNaN(concurrency)) {
-    concurrency = null;
-  }
-  return sharp.concurrency(concurrency);
-};
-
-/*
-  Get internal counters
-*/
-module.exports.counters = function() {
-  return sharp.counters();
-};
-
-/*
-  Get the version of the libvips library
-*/
-module.exports.libvipsVersion = function() {
-  return libvipsVersion;
-};

install/dll-copy.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+const copyFileSync = require('fs-copy-file-sync');
+const libvips = require('../lib/libvips');
+const npmLog = require('npmlog');
+
+if (process.platform === 'win32') {
+  const buildDir = path.join(__dirname, '..', 'build');
+  const buildReleaseDir = path.join(buildDir, 'Release');
+  npmLog.info('sharp', `Creating ${buildReleaseDir}`);
+  try {
+    libvips.mkdirSync(buildDir);
+    libvips.mkdirSync(buildReleaseDir);
+  } catch (err) {}
+  const vendorLibDir = path.join(__dirname, '..', 'vendor', 'lib');
+  npmLog.info('sharp', `Copying DLLs from ${vendorLibDir} to ${buildReleaseDir}`);
+  try {
+    fs
+      .readdirSync(vendorLibDir)
+      .filter(function (filename) {
+        return /\.dll$/.test(filename);
+      })
+      .forEach(function (filename) {
+        copyFileSync(
+          path.join(vendorLibDir, filename),
+          path.join(buildReleaseDir, filename)
+        );
+      });
+  } catch (err) {
+    npmLog.error('sharp', err.message);
+  }
+}

install/libvips.js

@@ -0,0 +1,109 @@
+'use strict';
+
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+const detectLibc = require('detect-libc');
+const npmLog = require('npmlog');
+const semver = require('semver');
+const simpleGet = require('simple-get');
+const tar = require('tar');
+const copyFileSync = require('fs-copy-file-sync');
+
+const agent = require('../lib/agent');
+const libvips = require('../lib/libvips');
+const platform = require('../lib/platform');
+
+const minimumLibvipsVersion = libvips.minimumLibvipsVersion;
+const distBaseUrl = process.env.npm_config_sharp_dist_base_url || process.env.SHARP_DIST_BASE_URL || `https://github.com/lovell/sharp-libvips/releases/download/v${minimumLibvipsVersion}/`;
+
+const fail = function (err) {
+  npmLog.error('sharp', err.message);
+  npmLog.info('sharp', 'Attempting to build from source via node-gyp but this may fail due to the above error');
+  npmLog.info('sharp', 'Please see https://sharp.pixelplumbing.com/page/install for required dependencies');
+  process.exit(1);
+};
+
+const extractTarball = function (tarPath) {
+  const vendorPath = path.join(__dirname, '..', 'vendor');
+  libvips.mkdirSync(vendorPath);
+  tar
+    .extract({
+      file: tarPath,
+      cwd: vendorPath,
+      strict: true
+    })
+    .catch(function (err) {
+      if (/unexpected end of file/.test(err.message)) {
+        npmLog.error('sharp', `Please delete ${tarPath} as it is not a valid tarball`);
+      }
+      fail(err);
+    });
+};
+
+try {
+  const useGlobalLibvips = libvips.useGlobalLibvips();
+  if (useGlobalLibvips) {
+    const globalLibvipsVersion = libvips.globalLibvipsVersion();
+    npmLog.info('sharp', `Detected globally-installed libvips v${globalLibvipsVersion}`);
+    npmLog.info('sharp', 'Building from source via node-gyp');
+    process.exit(1);
+  } else if (libvips.hasVendoredLibvips()) {
+    npmLog.info('sharp', `Using existing vendored libvips v${minimumLibvipsVersion}`);
+  } else {
+    // Is this arch/platform supported?
+    const arch = process.env.npm_config_arch || process.arch;
+    const platformAndArch = platform();
+    if (platformAndArch === 'win32-ia32') {
+      throw new Error('Windows x86 (32-bit) node.exe is not supported');
+    }
+    if (arch === 'ia32') {
+      throw new Error(`Intel Architecture 32-bit systems require manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    if (platformAndArch === 'freebsd-x64' || platformAndArch === 'openbsd-x64' || platformAndArch === 'sunos-x64') {
+      throw new Error(`BSD/SunOS systems require manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    if (detectLibc.family === detectLibc.GLIBC && detectLibc.version && semver.lt(`${detectLibc.version}.0`, '2.13.0')) {
+      throw new Error(`Use with glibc version ${detectLibc.version} requires manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    // Download to per-process temporary file
+    const tarFilename = ['libvips', minimumLibvipsVersion, platformAndArch].join('-') + '.tar.gz';
+    const tarPathCache = path.join(libvips.cachePath(), tarFilename);
+    if (fs.existsSync(tarPathCache)) {
+      npmLog.info('sharp', `Using cached ${tarPathCache}`);
+      extractTarball(tarPathCache);
+    } else {
+      const tarPathTemp = path.join(os.tmpdir(), `${process.pid}-${tarFilename}`);
+      const tmpFile = fs.createWriteStream(tarPathTemp);
+      const url = distBaseUrl + tarFilename;
+      npmLog.info('sharp', `Downloading ${url}`);
+      simpleGet({ url: url, agent: agent() }, function (err, response) {
+        if (err) {
+          throw err;
+        }
+        if (response.statusCode !== 200) {
+          throw new Error(`Status ${response.statusCode}`);
+        }
+        response
+          .on('error', fail)
+          .pipe(tmpFile);
+      });
+      tmpFile
+        .on('error', fail)
+        .on('close', function () {
+          try {
+            // Attempt to rename
+            fs.renameSync(tarPathTemp, tarPathCache);
+          } catch (err) {
+            // Fall back to copy and unlink
+            copyFileSync(tarPathTemp, tarPathCache);
+            fs.unlinkSync(tarPathTemp);
+          }
+          extractTarball(tarPathCache);
+        });
+    }
+  }
+} catch (err) {
+  fail(err);
+}

lib/agent.js

@@ -0,0 +1,37 @@
+'use strict';
+
+const url = require('url');
+const tunnelAgent = require('tunnel-agent');
+
+const is = require('./is');
+
+const proxies = [
+  'HTTPS_PROXY',
+  'https_proxy',
+  'HTTP_PROXY',
+  'http_proxy',
+  'npm_config_https_proxy',
+  'npm_config_proxy'
+];
+
+function env (key) {
+  return process.env[key];
+}
+
+module.exports = function () {
+  try {
+    const proxy = url.parse(proxies.map(env).find(is.string));
+    const tunnel = proxy.protocol === 'https:'
+      ? tunnelAgent.httpsOverHttps
+      : tunnelAgent.httpsOverHttp;
+    return tunnel({
+      proxy: {
+        port: Number(proxy.port),
+        host: proxy.hostname,
+        proxyAuth: proxy.auth
+      }
+    });
+  } catch (err) {
+    return null;
+  }
+};

lib/channel.js

@@ -0,0 +1,147 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Boolean operations for bandbool.
+ * @private
+ */
+const bool = {
+  and: 'and',
+  or: 'or',
+  eor: 'eor'
+};
+
+/**
+ * Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
+ *
+ * @example
+ * sharp('rgba.png')
+ *   .removeAlpha()
+ *   .toFile('rgb.png', function(err, info) {
+ *     // rgb.png is a 3 channel image without an alpha channel
+ *   });
+ *
+ * @returns {Sharp}
+ */
+function removeAlpha () {
+  this.options.removeAlpha = true;
+  return this;
+}
+
+/**
+ * Ensure alpha channel, if missing. The added alpha channel will be fully opaque. This is a no-op if the image already has an alpha channel.
+ *
+ * @example
+ * sharp('rgb.jpg')
+ *   .ensureAlpha()
+ *   .toFile('rgba.png', function(err, info) {
+ *     // rgba.png is a 4 channel image with a fully opaque alpha channel
+ *   });
+ *
+ * @returns {Sharp}
+ */
+function ensureAlpha () {
+  this.options.ensureAlpha = true;
+  return this;
+}
+
+/**
+ * Extract a single channel from a multi-channel image.
+ *
+ * @example
+ * sharp(input)
+ *   .extractChannel('green')
+ *   .toFile('input_green.jpg', function(err, info) {
+ *     // info.channels === 1
+ *     // input_green.jpg contains the green channel of the input image
+ *    });
+ *
+ * @param {Number|String} channel - zero-indexed band number to extract, or `red`, `green` or `blue` as alternative to `0`, `1` or `2` respectively.
+ * @returns {Sharp}
+ * @throws {Error} Invalid channel
+ */
+function extractChannel (channel) {
+  if (channel === 'red') {
+    channel = 0;
+  } else if (channel === 'green') {
+    channel = 1;
+  } else if (channel === 'blue') {
+    channel = 2;
+  }
+  if (is.integer(channel) && is.inRange(channel, 0, 4)) {
+    this.options.extractChannel = channel;
+  } else {
+    throw new Error('Cannot extract invalid channel ' + channel);
+  }
+  return this;
+}
+
+/**
+ * Join one or more channels to the image.
+ * The meaning of the added channels depends on the output colourspace, set with `toColourspace()`.
+ * By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+ * Channel ordering follows vips convention:
+ * - sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha.
+ * - CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha.
+ *
+ * Buffers may be any of the image formats supported by sharp: JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data.
+ * For raw pixel input, the `options` object should contain a `raw` attribute, which follows the format of the attribute of the same name in the `sharp()` constructor.
+ *
+ * @param {Array<String|Buffer>|String|Buffer} images - one or more images (file paths, Buffers).
+ * @param {Object} options - image options, see `sharp()` constructor.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function joinChannel (images, options) {
+  if (Array.isArray(images)) {
+    images.forEach(function (image) {
+      this.options.joinChannelIn.push(this._createInputDescriptor(image, options));
+    }, this);
+  } else {
+    this.options.joinChannelIn.push(this._createInputDescriptor(images, options));
+  }
+  return this;
+}
+
+/**
+ * Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.
+ *
+ * @example
+ * sharp('3-channel-rgb-input.png')
+ *   .bandbool(sharp.bool.and)
+ *   .toFile('1-channel-output.png', function (err, info) {
+ *     // The output will be a single channel image where each pixel `P = R & G & B`.
+ *     // If `I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111]`
+ *     // then `O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2`.
+ *   });
+ *
+ * @param {String} boolOp - one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function bandbool (boolOp) {
+  if (is.string(boolOp) && is.inArray(boolOp, ['and', 'or', 'eor'])) {
+    this.options.bandBoolOp = boolOp;
+  } else {
+    throw new Error('Invalid bandbool operation ' + boolOp);
+  }
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with channel-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    // Public instance functions
+    removeAlpha,
+    ensureAlpha,
+    extractChannel,
+    joinChannel,
+    bandbool
+  });
+  // Class attributes
+  Sharp.bool = bool;
+};

lib/colour.js

@@ -0,0 +1,119 @@
+'use strict';
+
+const color = require('color');
+const is = require('./is');
+
+/**
+ * Colourspaces.
+ * @private
+ */
+const colourspace = {
+  multiband: 'multiband',
+  'b-w': 'b-w',
+  bw: 'b-w',
+  cmyk: 'cmyk',
+  srgb: 'srgb'
+};
+
+/**
+ * Tint the image using the provided chroma while preserving the image luminance.
+ * An alpha channel may be present and will be unchanged by the operation.
+ *
+ * @param {String|Object} rgb - parsed by the [color](https://www.npmjs.org/package/color) module to extract chroma values.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameter
+ */
+function tint (rgb) {
+  const colour = color(rgb);
+  this.options.tintA = colour.a();
+  this.options.tintB = colour.b();
+  return this;
+}
+
+/**
+ * Convert to 8-bit greyscale; 256 shades of grey.
+ * This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use `gamma()` with `greyscale()` for the best results.
+ * By default the output image will be web-friendly sRGB and contain three (identical) color channels.
+ * This may be overridden by other sharp operations such as `toColourspace('b-w')`,
+ * which will produce an output image containing one color channel.
+ * An alpha channel may be present, and will be unchanged by the operation.
+ * @param {Boolean} [greyscale=true]
+ * @returns {Sharp}
+ */
+function greyscale (greyscale) {
+  this.options.greyscale = is.bool(greyscale) ? greyscale : true;
+  return this;
+}
+
+/**
+ * Alternative spelling of `greyscale`.
+ * @param {Boolean} [grayscale=true]
+ * @returns {Sharp}
+ */
+function grayscale (grayscale) {
+  return this.greyscale(grayscale);
+}
+
+/**
+ * Set the output colourspace.
+ * By default output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+ * @param {String} [colourspace] - output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function toColourspace (colourspace) {
+  if (!is.string(colourspace)) {
+    throw new Error('Invalid output colourspace ' + colourspace);
+  }
+  this.options.colourspace = colourspace;
+  return this;
+}
+
+/**
+ * Alternative spelling of `toColourspace`.
+ * @param {String} [colorspace] - output colorspace.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function toColorspace (colorspace) {
+  return this.toColourspace(colorspace);
+}
+
+/**
+ * Update a colour attribute of the this.options Object.
+ * @private
+ * @param {String} key
+ * @param {String|Object} val
+ * @throws {Error} Invalid key
+ */
+function _setColourOption (key, val) {
+  if (is.object(val) || is.string(val)) {
+    const colour = color(val);
+    this.options[key] = [
+      colour.red(),
+      colour.green(),
+      colour.blue(),
+      Math.round(colour.alpha() * 255)
+    ];
+  }
+}
+
+/**
+ * Decorate the Sharp prototype with colour-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    // Public
+    tint,
+    greyscale,
+    grayscale,
+    toColourspace,
+    toColorspace,
+    // Private
+    _setColourOption
+  });
+  // Class attributes
+  Sharp.colourspace = colourspace;
+  Sharp.colorspace = colourspace;
+};

lib/composite.js

@@ -0,0 +1,174 @@
+'use strict';
+
+const deprecate = require('util').deprecate;
+
+const is = require('./is');
+
+/**
+ * Blend modes.
+ * @member
+ * @private
+ */
+const blend = {
+  clear: 'clear',
+  source: 'source',
+  over: 'over',
+  in: 'in',
+  out: 'out',
+  atop: 'atop',
+  dest: 'dest',
+  'dest-over': 'dest-over',
+  'dest-in': 'dest-in',
+  'dest-out': 'dest-out',
+  'dest-atop': 'dest-atop',
+  xor: 'xor',
+  add: 'add',
+  saturate: 'saturate',
+  multiply: 'multiply',
+  screen: 'screen',
+  overlay: 'overlay',
+  darken: 'darken',
+  lighten: 'lighten',
+  'colour-dodge': 'colour-dodge',
+  'color-dodge': 'colour-dodge',
+  'colour-burn': 'colour-burn',
+  'color-burn': 'colour-burn',
+  'hard-light': 'hard-light',
+  'soft-light': 'soft-light',
+  difference: 'difference',
+  exclusion: 'exclusion'
+};
+
+/**
+ * Composite image(s) over the processed (resized, extracted etc.) image.
+ *
+ * The images to composite must be the same size or smaller than the processed image.
+ * If both `top` and `left` options are provided, they take precedence over `gravity`.
+ *
+ * The `blend` option can be one of `clear`, `source`, `over`, `in`, `out`, `atop`,
+ * `dest`, `dest-over`, `dest-in`, `dest-out`, `dest-atop`,
+ * `xor`, `add`, `saturate`, `multiply`, `screen`, `overlay`, `darken`, `lighten`,
+ * `colour-dodge`, `color-dodge`, `colour-burn`,`color-burn`,
+ * `hard-light`, `soft-light`, `difference`, `exclusion`.
+ *
+ * More information about blend modes can be found at
+ * https://libvips.github.io/libvips/API/current/libvips-conversion.html#VipsBlendMode
+ * and https://www.cairographics.org/operators/
+ *
+ * @example
+ * sharp('input.png')
+ *   .rotate(180)
+ *   .resize(300)
+ *   .flatten( { background: '#ff6600' } )
+ *   .composite([{ input: 'overlay.png', gravity: 'southeast' }])
+ *   .sharpen()
+ *   .withMetadata()
+ *   .webp( { quality: 90 } )
+ *   .toBuffer()
+ *   .then(function(outputBuffer) {
+ *     // outputBuffer contains upside down, 300px wide, alpha channel flattened
+ *     // onto orange background, composited with overlay.png with SE gravity,
+ *     // sharpened, with metadata, 90% quality WebP image data. Phew!
+ *   });
+ *
+ * @param {Object[]} images - Ordered list of images to composite
+ * @param {Buffer|String} [images[].input] - Buffer containing image data or String containing the path to an image file.
+ * @param {String} [images[].blend='over'] - how to blend this image with the image below.
+ * @param {String} [images[].gravity='centre'] - gravity at which to place the overlay.
+ * @param {Number} [images[].top] - the pixel offset from the top edge.
+ * @param {Number} [images[].left] - the pixel offset from the left edge.
+ * @param {Boolean} [images[].tile=false] - set to true to repeat the overlay image across the entire image with the given `gravity`.
+ * @param {Number} [images[].density=72] - number representing the DPI for vector overlay image.
+ * @param {Object} [images[].raw] - describes overlay when using raw pixel data.
+ * @param {Number} [images[].raw.width]
+ * @param {Number} [images[].raw.height]
+ * @param {Number} [images[].raw.channels]
+ * @param {Object} [images[].create] - describes a blank overlay to be created.
+ * @param {Number} [images[].create.width]
+ * @param {Number} [images[].create.height]
+ * @param {Number} [images[].create.channels] - 3-4
+ * @param {String|Object} [images[].create.background] - parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function composite (images) {
+  if (!Array.isArray(images)) {
+    throw is.invalidParameterError('images to composite', 'array', images);
+  }
+  this.options.composite = images.map(image => {
+    if (!is.object(image)) {
+      throw is.invalidParameterError('image to composite', 'object', image);
+    }
+    const { raw, density } = image;
+    const inputOptions = (raw || density) ? { raw, density } : undefined;
+    const composite = {
+      input: this._createInputDescriptor(image.input, inputOptions, { allowStream: false }),
+      blend: 'over',
+      tile: false,
+      left: -1,
+      top: -1,
+      gravity: 0
+    };
+    if (is.defined(image.blend)) {
+      if (is.string(blend[image.blend])) {
+        composite.blend = blend[image.blend];
+      } else {
+        throw is.invalidParameterError('blend', 'valid blend name', image.blend);
+      }
+    }
+    if (is.defined(image.tile)) {
+      if (is.bool(image.tile)) {
+        composite.tile = image.tile;
+      } else {
+        throw is.invalidParameterError('tile', 'boolean', image.tile);
+      }
+    }
+    if (is.defined(image.left)) {
+      if (is.integer(image.left) && image.left >= 0) {
+        composite.left = image.left;
+      } else {
+        throw is.invalidParameterError('left', 'positive integer', image.left);
+      }
+    }
+    if (is.defined(image.top)) {
+      if (is.integer(image.top) && image.top >= 0) {
+        composite.top = image.top;
+      } else {
+        throw is.invalidParameterError('top', 'positive integer', image.top);
+      }
+    }
+    if (composite.left !== composite.top && Math.min(composite.left, composite.top) === -1) {
+      throw new Error('Expected both left and top to be set');
+    }
+    if (is.defined(image.gravity)) {
+      if (is.integer(image.gravity) && is.inRange(image.gravity, 0, 8)) {
+        composite.gravity = image.gravity;
+      } else if (is.string(image.gravity) && is.integer(this.constructor.gravity[image.gravity])) {
+        composite.gravity = this.constructor.gravity[image.gravity];
+      } else {
+        throw is.invalidParameterError('gravity', 'valid gravity', image.gravity);
+      }
+    }
+    return composite;
+  });
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+ */
+function overlayWith (input, options) {
+  const blend = (is.object(options) && options.cutout) ? 'dest-in' : 'over';
+  return this.composite([Object.assign({ input, blend }, options)]);
+}
+
+/**
+ * Decorate the Sharp prototype with composite-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Sharp.prototype.composite = composite;
+  Sharp.prototype.overlayWith = deprecate(overlayWith, 'overlayWith(input, options) is deprecated, use composite([{ input, ...options }]) instead');
+  Sharp.blend = blend;
+};

lib/constructor.js

@@ -0,0 +1,241 @@
+'use strict';
+
+const path = require('path');
+const util = require('util');
+const stream = require('stream');
+const events = require('events');
+const is = require('./is');
+
+require('./libvips').hasVendoredLibvips();
+const sharp = require('bindings')('sharp.node');
+
+// Use NODE_DEBUG=sharp to enable libvips warnings
+const debuglog = util.debuglog('sharp');
+
+/**
+ * @class Sharp
+ *
+ * Constructor factory to create an instance of `sharp`, to which further methods are chained.
+ *
+ * JPEG, PNG, WebP or TIFF format image data can be streamed out from this object.
+ * When using Stream based output, derived attributes are available from the `info` event.
+ *
+ * Implements the [stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
+ *
+ * @example
+ * sharp('input.jpg')
+ *   .resize(300, 200)
+ *   .toFile('output.jpg', function(err) {
+ *     // output.jpg is a 300 pixels wide and 200 pixels high image
+ *     // containing a scaled and cropped version of input.jpg
+ *   });
+ *
+ * @example
+ * // Read image data from readableStream,
+ * // resize to 300 pixels wide,
+ * // emit an 'info' event with calculated dimensions
+ * // and finally write image data to writableStream
+ * var transformer = sharp()
+ *   .resize(300)
+ *   .on('info', function(info) {
+ *     console.log('Image height is ' + info.height);
+ *   });
+ * readableStream.pipe(transformer).pipe(writableStream);
+ *
+ * @example
+ * // Create a blank 300x200 PNG image of semi-transluent red pixels
+ * sharp({
+ *   create: {
+ *     width: 300,
+ *     height: 200,
+ *     channels: 4,
+ *     background: { r: 255, g: 0, b: 0, alpha: 0.5 }
+ *   }
+ * })
+ * .png()
+ * .toBuffer()
+ * .then( ... );
+ *
+ * @param {(Buffer|String)} [input] - if present, can be
+ *  a Buffer containing JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data, or
+ *  a String containing the path to an JPEG, PNG, WebP, GIF, SVG or TIFF image file.
+ *  JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data can be streamed into the object when not present.
+ * @param {Object} [options] - if present, is an Object with optional attributes.
+ * @param {Boolean} [options.failOnError=true] - by default halt processing and raise an error when loading invalid images.
+ *  Set this flag to `false` if you'd rather apply a "best effort" to decode images, even if the data is corrupt or invalid.
+ * @param {Number} [options.density=72] - number representing the DPI for vector images.
+ * @param {Number} [options.pages=1] - number of pages to extract for multi-page input (GIF, TIFF, PDF), use -1 for all pages.
+ * @param {Number} [options.page=0] - page number to start extracting from for multi-page input (GIF, TIFF, PDF), zero based.
+ * @param {Object} [options.raw] - describes raw pixel input image data. See `raw()` for pixel ordering.
+ * @param {Number} [options.raw.width]
+ * @param {Number} [options.raw.height]
+ * @param {Number} [options.raw.channels] - 1-4
+ * @param {Object} [options.create] - describes a new image to be created.
+ * @param {Number} [options.create.width]
+ * @param {Number} [options.create.height]
+ * @param {Number} [options.create.channels] - 3-4
+ * @param {String|Object} [options.create.background] - parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const Sharp = function (input, options) {
+  if (arguments.length === 1 && !is.defined(input)) {
+    throw new Error('Invalid input');
+  }
+  if (!(this instanceof Sharp)) {
+    return new Sharp(input, options);
+  }
+  stream.Duplex.call(this);
+  this.options = {
+    // input options
+    sequentialRead: false,
+    limitInputPixels: Math.pow(0x3FFF, 2),
+    // ICC profiles
+    iccProfilePath: path.join(__dirname, 'icc') + path.sep,
+    // resize options
+    topOffsetPre: -1,
+    leftOffsetPre: -1,
+    widthPre: -1,
+    heightPre: -1,
+    topOffsetPost: -1,
+    leftOffsetPost: -1,
+    widthPost: -1,
+    heightPost: -1,
+    width: -1,
+    height: -1,
+    canvas: 'crop',
+    position: 0,
+    resizeBackground: [0, 0, 0, 255],
+    useExifOrientation: false,
+    angle: 0,
+    rotationAngle: 0,
+    rotationBackground: [0, 0, 0, 255],
+    rotateBeforePreExtract: false,
+    flip: false,
+    flop: false,
+    extendTop: 0,
+    extendBottom: 0,
+    extendLeft: 0,
+    extendRight: 0,
+    extendBackground: [0, 0, 0, 255],
+    withoutEnlargement: false,
+    kernel: 'lanczos3',
+    fastShrinkOnLoad: true,
+    // operations
+    tintA: 128,
+    tintB: 128,
+    flatten: false,
+    flattenBackground: [0, 0, 0],
+    negate: false,
+    medianSize: 0,
+    blurSigma: 0,
+    sharpenSigma: 0,
+    sharpenFlat: 1,
+    sharpenJagged: 2,
+    threshold: 0,
+    thresholdGrayscale: true,
+    trimThreshold: 0,
+    gamma: 0,
+    gammaOut: 0,
+    greyscale: false,
+    normalise: 0,
+    booleanBufferIn: null,
+    booleanFileIn: '',
+    joinChannelIn: [],
+    extractChannel: -1,
+    removeAlpha: false,
+    ensureAlpha: false,
+    colourspace: 'srgb',
+    composite: [],
+    // output
+    fileOut: '',
+    formatOut: 'input',
+    streamOut: false,
+    withMetadata: false,
+    withMetadataOrientation: -1,
+    resolveWithObject: false,
+    // output format
+    jpegQuality: 80,
+    jpegProgressive: false,
+    jpegChromaSubsampling: '4:2:0',
+    jpegTrellisQuantisation: false,
+    jpegOvershootDeringing: false,
+    jpegOptimiseScans: false,
+    jpegOptimiseCoding: true,
+    jpegQuantisationTable: 0,
+    pngProgressive: false,
+    pngCompressionLevel: 9,
+    pngAdaptiveFiltering: false,
+    pngPalette: false,
+    pngQuality: 100,
+    pngColours: 256,
+    pngDither: 1,
+    webpQuality: 80,
+    webpAlphaQuality: 100,
+    webpLossless: false,
+    webpNearLossless: false,
+    tiffQuality: 80,
+    tiffCompression: 'jpeg',
+    tiffPredictor: 'horizontal',
+    tiffPyramid: false,
+    tiffSquash: false,
+    tiffTile: false,
+    tiffTileHeight: 256,
+    tiffTileWidth: 256,
+    tiffXres: 1.0,
+    tiffYres: 1.0,
+    tileSize: 256,
+    tileOverlap: 0,
+    linearA: 1,
+    linearB: 0,
+    // Function to notify of libvips warnings
+    debuglog: debuglog,
+    // Function to notify of queue length changes
+    queueListener: function (queueLength) {
+      queue.emit('change', queueLength);
+    }
+  };
+  this.options.input = this._createInputDescriptor(input, options, { allowStream: true });
+  return this;
+};
+util.inherits(Sharp, stream.Duplex);
+
+/**
+ * An EventEmitter that emits a `change` event when a task is either:
+ * - queued, waiting for _libuv_ to provide a worker thread
+ * - complete
+ * @member
+ * @example
+ * sharp.queue.on('change', function(queueLength) {
+ *   console.log('Queue contains ' + queueLength + ' task(s)');
+ * });
+ */
+const queue = new events.EventEmitter();
+Sharp.queue = queue;
+
+/**
+ * An Object containing nested boolean values representing the available input and output formats/methods.
+ * @example
+ * console.log(sharp.format);
+ * @returns {Object}
+ */
+Sharp.format = sharp.format();
+
+/**
+ * An Object containing the version numbers of libvips and its dependencies.
+ * @member
+ * @example
+ * console.log(sharp.versions);
+ */
+Sharp.versions = {
+  vips: sharp.libvipsVersion()
+};
+try {
+  Sharp.versions = require('../vendor/versions.json');
+} catch (err) {}
+
+/**
+ * Export constructor.
+ * @private
+ */
+module.exports = Sharp;

lib/index.js

@@ -0,0 +1,13 @@
+'use strict';
+
+const Sharp = require('./constructor');
+require('./input')(Sharp);
+require('./resize')(Sharp);
+require('./composite')(Sharp);
+require('./operation')(Sharp);
+require('./colour')(Sharp);
+require('./channel')(Sharp);
+require('./output')(Sharp);
+require('./utility')(Sharp);
+
+module.exports = Sharp;

lib/input.js

@@ -0,0 +1,389 @@
+'use strict';
+
+const color = require('color');
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Create Object containing input and input-related options.
+ * @private
+ */
+function _createInputDescriptor (input, inputOptions, containerOptions) {
+  const inputDescriptor = { failOnError: true };
+  if (is.string(input)) {
+    // filesystem
+    inputDescriptor.file = input;
+  } else if (is.buffer(input)) {
+    // Buffer
+    inputDescriptor.buffer = input;
+  } else if (is.plainObject(input) && !is.defined(inputOptions)) {
+    // Plain Object descriptor, e.g. create
+    inputOptions = input;
+    if (is.plainObject(inputOptions.raw)) {
+      // Raw Stream
+      inputDescriptor.buffer = [];
+    }
+  } else if (!is.defined(input) && is.object(containerOptions) && containerOptions.allowStream) {
+    // Stream
+    inputDescriptor.buffer = [];
+  } else {
+    throw new Error('Unsupported input ' + typeof input);
+  }
+  if (is.object(inputOptions)) {
+    // Fail on error
+    if (is.defined(inputOptions.failOnError)) {
+      if (is.bool(inputOptions.failOnError)) {
+        inputDescriptor.failOnError = inputOptions.failOnError;
+      } else {
+        throw new Error('Invalid failOnError (boolean) ' + inputOptions.failOnError);
+      }
+    }
+    // Density
+    if (is.defined(inputOptions.density)) {
+      if (is.inRange(inputOptions.density, 1, 2400)) {
+        inputDescriptor.density = inputOptions.density;
+      } else {
+        throw new Error('Invalid density (1 to 2400) ' + inputOptions.density);
+      }
+    }
+    // Raw pixel input
+    if (is.defined(inputOptions.raw)) {
+      if (
+        is.object(inputOptions.raw) &&
+        is.integer(inputOptions.raw.width) && inputOptions.raw.width > 0 &&
+        is.integer(inputOptions.raw.height) && inputOptions.raw.height > 0 &&
+        is.integer(inputOptions.raw.channels) && is.inRange(inputOptions.raw.channels, 1, 4)
+      ) {
+        inputDescriptor.rawWidth = inputOptions.raw.width;
+        inputDescriptor.rawHeight = inputOptions.raw.height;
+        inputDescriptor.rawChannels = inputOptions.raw.channels;
+      } else {
+        throw new Error('Expected width, height and channels for raw pixel input');
+      }
+    }
+    // Multi-page input (GIF, TIFF, PDF)
+    if (is.defined(inputOptions.pages)) {
+      if (is.integer(inputOptions.pages) && is.inRange(inputOptions.pages, -1, 100000)) {
+        inputDescriptor.pages = inputOptions.pages;
+      }
+    }
+    if (is.defined(inputOptions.page)) {
+      if (is.integer(inputOptions.page) && is.inRange(inputOptions.page, 0, 100000)) {
+        inputDescriptor.page = inputOptions.page;
+      }
+    }
+    // Create new image
+    if (is.defined(inputOptions.create)) {
+      if (
+        is.object(inputOptions.create) &&
+        is.integer(inputOptions.create.width) && inputOptions.create.width > 0 &&
+        is.integer(inputOptions.create.height) && inputOptions.create.height > 0 &&
+        is.integer(inputOptions.create.channels) && is.inRange(inputOptions.create.channels, 3, 4) &&
+        is.defined(inputOptions.create.background)
+      ) {
+        inputDescriptor.createWidth = inputOptions.create.width;
+        inputDescriptor.createHeight = inputOptions.create.height;
+        inputDescriptor.createChannels = inputOptions.create.channels;
+        const background = color(inputOptions.create.background);
+        inputDescriptor.createBackground = [
+          background.red(),
+          background.green(),
+          background.blue(),
+          Math.round(background.alpha() * 255)
+        ];
+        delete inputDescriptor.buffer;
+      } else {
+        throw new Error('Expected width, height, channels and background to create a new input image');
+      }
+    }
+  } else if (is.defined(inputOptions)) {
+    throw new Error('Invalid input options ' + inputOptions);
+  }
+  return inputDescriptor;
+}
+
+/**
+ * Handle incoming Buffer chunk on Writable Stream.
+ * @private
+ * @param {Buffer} chunk
+ * @param {String} encoding - unused
+ * @param {Function} callback
+ */
+function _write (chunk, encoding, callback) {
+  /* istanbul ignore else */
+  if (Array.isArray(this.options.input.buffer)) {
+    /* istanbul ignore else */
+    if (is.buffer(chunk)) {
+      if (this.options.input.buffer.length === 0) {
+        const that = this;
+        this.on('finish', function () {
+          that.streamInFinished = true;
+        });
+      }
+      this.options.input.buffer.push(chunk);
+      callback();
+    } else {
+      callback(new Error('Non-Buffer data on Writable Stream'));
+    }
+  } else {
+    callback(new Error('Unexpected data on Writable Stream'));
+  }
+}
+
+/**
+ * Flattens the array of chunks accumulated in input.buffer.
+ * @private
+ */
+function _flattenBufferIn () {
+  if (this._isStreamInput()) {
+    this.options.input.buffer = Buffer.concat(this.options.input.buffer);
+  }
+}
+
+/**
+ * Are we expecting Stream-based input?
+ * @private
+ * @returns {Boolean}
+ */
+function _isStreamInput () {
+  return Array.isArray(this.options.input.buffer);
+}
+
+/**
+ * Take a "snapshot" of the Sharp instance, returning a new instance.
+ * Cloned instances inherit the input of their parent instance.
+ * This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.
+ *
+ * @example
+ * const pipeline = sharp().rotate();
+ * pipeline.clone().resize(800, 600).pipe(firstWritableStream);
+ * pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
+ * readableStream.pipe(pipeline);
+ * // firstWritableStream receives auto-rotated, resized readableStream
+ * // secondWritableStream receives auto-rotated, extracted region of readableStream
+ *
+ * @returns {Sharp}
+ */
+function clone () {
+  const that = this;
+  // Clone existing options
+  const clone = this.constructor.call();
+  clone.options = Object.assign({}, this.options);
+  // Pass 'finish' event to clone for Stream-based input
+  if (this._isStreamInput()) {
+    this.on('finish', function () {
+      // Clone inherits input data
+      that._flattenBufferIn();
+      clone.options.bufferIn = that.options.bufferIn;
+      clone.emit('finish');
+    });
+  }
+  return clone;
+}
+
+/**
+ * Fast access to (uncached) image metadata without decoding any compressed image data.
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * - `format`: Name of decoder used to decompress image data e.g. `jpeg`, `png`, `webp`, `gif`, `svg`
+ * - `size`: Total size of image in bytes, for Stream and Buffer input only
+ * - `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
+ * - `height`: Number of pixels high (EXIF orientation is not taken into consideration)
+ * - `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636)
+ * - `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+ * - `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672)
+ * - `density`: Number of pixels per inch (DPI), if present
+ * - `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
+ * - `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+ * - `pages`: Number of pages/frames contained within the image, with support for TIFF, PDF, animated GIF and animated WebP
+ * - `pageHeight`: Number of pixels high each page in this PDF image will be.
+ * - `hasProfile`: Boolean indicating the presence of an embedded ICC profile
+ * - `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
+ * - `orientation`: Number value of the EXIF Orientation header, if present
+ * - `exif`: Buffer containing raw EXIF data, if present
+ * - `icc`: Buffer containing raw [ICC](https://www.npmjs.com/package/icc) profile data, if present
+ * - `iptc`: Buffer containing raw IPTC data, if present
+ * - `xmp`: Buffer containing raw XMP data, if present
+ *
+ * @example
+ * const image = sharp(inputJpg);
+ * image
+ *   .metadata()
+ *   .then(function(metadata) {
+ *     return image
+ *       .resize(Math.round(metadata.width / 2))
+ *       .webp()
+ *       .toBuffer();
+ *   })
+ *   .then(function(data) {
+ *     // data contains a WebP image half the width and height of the original JPEG
+ *   });
+ *
+ * @param {Function} [callback] - called with the arguments `(err, metadata)`
+ * @returns {Promise<Object>|Sharp}
+ */
+function metadata (callback) {
+  const that = this;
+  if (is.fn(callback)) {
+    if (this._isStreamInput()) {
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.metadata(that.options, callback);
+      });
+    } else {
+      sharp.metadata(this.options, callback);
+    }
+    return this;
+  } else {
+    if (this._isStreamInput()) {
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.metadata(that.options, function (err, metadata) {
+            if (err) {
+              reject(err);
+            } else {
+              resolve(metadata);
+            }
+          });
+        });
+      });
+    } else {
+      return new Promise(function (resolve, reject) {
+        sharp.metadata(that.options, function (err, metadata) {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(metadata);
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Access to pixel-derived image statistics for every channel in the image.
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * - `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
+ *     - `min` (minimum value in the channel)
+ *     - `max` (maximum value in the channel)
+ *     - `sum` (sum of all values in a channel)
+ *     - `squaresSum` (sum of squared values in a channel)
+ *     - `mean` (mean of the values in a channel)
+ *     - `stdev` (standard deviation for the values in a channel)
+ *     - `minX` (x-coordinate of one of the pixel where the minimum lies)
+ *     - `minY` (y-coordinate of one of the pixel where the minimum lies)
+ *     - `maxX` (x-coordinate of one of the pixel where the maximum lies)
+ *     - `maxY` (y-coordinate of one of the pixel where the maximum lies)
+ * - `isOpaque`: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel
+ * - `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
+ *
+ * @example
+ * const image = sharp(inputJpg);
+ * image
+ *   .stats()
+ *   .then(function(stats) {
+ *      // stats contains the channel-wise statistics array and the isOpaque value
+ *   });
+ *
+ * @param {Function} [callback] - called with the arguments `(err, stats)`
+ * @returns {Promise<Object>}
+ */
+function stats (callback) {
+  const that = this;
+  if (is.fn(callback)) {
+    if (this._isStreamInput()) {
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.stats(that.options, callback);
+      });
+    } else {
+      sharp.stats(this.options, callback);
+    }
+    return this;
+  } else {
+    if (this._isStreamInput()) {
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.stats(that.options, function (err, stats) {
+            if (err) {
+              reject(err);
+            } else {
+              resolve(stats);
+            }
+          });
+        });
+      });
+    } else {
+      return new Promise(function (resolve, reject) {
+        sharp.stats(that.options, function (err, stats) {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(stats);
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Do not process input images where the number of pixels (width x height) exceeds this limit.
+ * Assumes image dimensions contained in the input metadata can be trusted.
+ * The default limit is 268402689 (0x3FFF x 0x3FFF) pixels.
+ * @param {(Number|Boolean)} limit - an integral Number of pixels, zero or false to remove limit, true to use default limit.
+ * @returns {Sharp}
+ * @throws {Error} Invalid limit
+*/
+function limitInputPixels (limit) {
+  // if we pass in false we represent the integer as 0 to disable
+  if (limit === false) {
+    limit = 0;
+  } else if (limit === true) {
+    limit = Math.pow(0x3FFF, 2);
+  }
+  if (is.integer(limit) && limit >= 0) {
+    this.options.limitInputPixels = limit;
+  } else {
+    throw is.invalidParameterError('limitInputPixels', 'integer', limit);
+  }
+  return this;
+}
+
+/**
+ * An advanced setting that switches the libvips access method to `VIPS_ACCESS_SEQUENTIAL`.
+ * This will reduce memory usage and can improve performance on some systems.
+ *
+ * The default behaviour *before* function call is `false`, meaning the libvips access method is not sequential.
+ *
+ * @param {Boolean} [sequentialRead=true]
+ * @returns {Sharp}
+ */
+function sequentialRead (sequentialRead) {
+  this.options.sequentialRead = is.bool(sequentialRead) ? sequentialRead : true;
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with input-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    // Private
+    _createInputDescriptor,
+    _write,
+    _flattenBufferIn,
+    _isStreamInput,
+    // Public
+    clone,
+    metadata,
+    stats,
+    limitInputPixels,
+    sequentialRead
+  });
+};

lib/is.js

@@ -0,0 +1,119 @@
+'use strict';
+
+/**
+ * Is this value defined and not null?
+ * @private
+ */
+const defined = function (val) {
+  return typeof val !== 'undefined' && val !== null;
+};
+
+/**
+ * Is this value an object?
+ * @private
+ */
+const object = function (val) {
+  return typeof val === 'object';
+};
+
+/**
+ * Is this value a plain object?
+ * @private
+ */
+const plainObject = function (val) {
+  return object(val) && Object.prototype.toString.call(val) === '[object Object]';
+};
+
+/**
+ * Is this value a function?
+ * @private
+ */
+const fn = function (val) {
+  return typeof val === 'function';
+};
+
+/**
+ * Is this value a boolean?
+ * @private
+ */
+const bool = function (val) {
+  return typeof val === 'boolean';
+};
+
+/**
+ * Is this value a Buffer object?
+ * @private
+ */
+const buffer = function (val) {
+  return object(val) && val instanceof Buffer;
+};
+
+/**
+ * Is this value a non-empty string?
+ * @private
+ */
+const string = function (val) {
+  return typeof val === 'string' && val.length > 0;
+};
+
+/**
+ * Is this value a real number?
+ * @private
+ */
+const number = function (val) {
+  return typeof val === 'number' && !Number.isNaN(val);
+};
+
+/**
+ * Is this value an integer?
+ * @private
+ */
+const integer = function (val) {
+  return number(val) && val % 1 === 0;
+};
+
+/**
+ * Is this value within an inclusive given range?
+ * @private
+ */
+const inRange = function (val, min, max) {
+  return val >= min && val <= max;
+};
+
+/**
+ * Is this value within the elements of an array?
+ * @private
+ */
+const inArray = function (val, list) {
+  return list.indexOf(val) !== -1;
+};
+
+/**
+ * Create an Error with a message relating to an invalid parameter.
+ *
+ * @param {String} name - parameter name.
+ * @param {String} expected - description of the type/value/range expected.
+ * @param {*} actual - the value received.
+ * @returns {Error} Containing the formatted message.
+ * @private
+ */
+const invalidParameterError = function (name, expected, actual) {
+  return new Error(
+    `Expected ${expected} for ${name} but received ${actual} of type ${typeof actual}`
+  );
+};
+
+module.exports = {
+  defined: defined,
+  object: object,
+  plainObject: plainObject,
+  fn: fn,
+  bool: bool,
+  buffer: buffer,
+  string: string,
+  number: number,
+  integer: integer,
+  inRange: inRange,
+  inArray: inArray,
+  invalidParameterError: invalidParameterError
+};

lib/libvips.js

@@ -0,0 +1,95 @@
+'use strict';
+
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const spawnSync = require('child_process').spawnSync;
+const semver = require('semver');
+const platform = require('./platform');
+
+const env = process.env;
+const minimumLibvipsVersion = env.npm_package_config_libvips || require('../package.json').config.libvips;
+
+const spawnSyncOptions = {
+  encoding: 'utf8',
+  shell: true
+};
+
+const mkdirSync = function (dirPath) {
+  try {
+    fs.mkdirSync(dirPath);
+  } catch (err) {
+    if (err.code !== 'EEXIST') {
+      throw err;
+    }
+  }
+};
+
+const cachePath = function () {
+  const npmCachePath = env.npm_config_cache || (env.APPDATA ? path.join(env.APPDATA, 'npm-cache') : path.join(os.homedir(), '.npm'));
+  mkdirSync(npmCachePath);
+  const libvipsCachePath = path.join(npmCachePath, '_libvips');
+  mkdirSync(libvipsCachePath);
+  return libvipsCachePath;
+};
+
+const globalLibvipsVersion = function () {
+  if (process.platform !== 'win32') {
+    const globalLibvipsVersion = spawnSync(`PKG_CONFIG_PATH="${pkgConfigPath()}" pkg-config --modversion vips-cpp`, spawnSyncOptions).stdout || '';
+    return globalLibvipsVersion.trim();
+  } else {
+    return '';
+  }
+};
+
+const hasVendoredLibvips = function () {
+  const currentPlatformId = platform();
+  const vendorPath = path.join(__dirname, '..', 'vendor');
+  let vendorVersionId;
+  let vendorPlatformId;
+  try {
+    vendorVersionId = require(path.join(vendorPath, 'versions.json')).vips;
+    vendorPlatformId = require(path.join(vendorPath, 'platform.json'));
+  } catch (err) {}
+  if (vendorVersionId && vendorVersionId !== minimumLibvipsVersion) {
+    throw new Error(`Found vendored libvips v${vendorVersionId} but require v${minimumLibvipsVersion}. Please remove the 'node_modules/sharp/vendor' directory and run 'npm install'.`);
+  }
+  if (vendorPlatformId) {
+    if (currentPlatformId === vendorPlatformId) {
+      return true;
+    } else {
+      throw new Error(`'${vendorPlatformId}' binaries cannot be used on the '${currentPlatformId}' platform. Please remove the 'node_modules/sharp/vendor' directory and run 'npm install'.`);
+    }
+  }
+  return false;
+};
+
+const pkgConfigPath = function () {
+  if (process.platform !== 'win32') {
+    const brewPkgConfigPath = spawnSync('which brew >/dev/null 2>&1 && eval $(brew --env) && echo $PKG_CONFIG_LIBDIR', spawnSyncOptions).stdout || '';
+    return [brewPkgConfigPath.trim(), env.PKG_CONFIG_PATH, '/usr/local/lib/pkgconfig', '/usr/lib/pkgconfig']
+      .filter(function (p) { return !!p; })
+      .join(':');
+  } else {
+    return '';
+  }
+};
+
+const useGlobalLibvips = function () {
+  if (Boolean(env.SHARP_IGNORE_GLOBAL_LIBVIPS) === true) {
+    return false;
+  }
+
+  const globalVipsVersion = globalLibvipsVersion();
+  return !!globalVipsVersion && semver.gte(globalVipsVersion, minimumLibvipsVersion);
+};
+
+module.exports = {
+  minimumLibvipsVersion: minimumLibvipsVersion,
+  cachePath: cachePath,
+  globalLibvipsVersion: globalLibvipsVersion,
+  hasVendoredLibvips: hasVendoredLibvips,
+  pkgConfigPath: pkgConfigPath,
+  useGlobalLibvips: useGlobalLibvips,
+  mkdirSync: mkdirSync
+};

lib/operation.js

@@ -0,0 +1,441 @@
+'use strict';
+
+const color = require('color');
+const is = require('./is');
+
+/**
+ * Rotate the output image by either an explicit angle
+ * or auto-orient based on the EXIF `Orientation` tag.
+ *
+ * If an angle is provided, it is converted to a valid positive degree rotation.
+ * For example, `-450` will produce a 270deg rotation.
+ *
+ * When rotating by an angle other than a multiple of 90,
+ * the background colour can be provided with the `background` option.
+ *
+ * If no angle is provided, it is determined from the EXIF data.
+ * Mirroring is supported and may infer the use of a flip operation.
+ *
+ * The use of `rotate` implies the removal of the EXIF `Orientation` tag, if any.
+ *
+ * Method order is important when both rotating and extracting regions,
+ * for example `rotate(x).extract(y)` will produce a different result to `extract(y).rotate(x)`.
+ *
+ * @example
+ * const pipeline = sharp()
+ *   .rotate()
+ *   .resize(null, 200)
+ *   .toBuffer(function (err, outputBuffer, info) {
+ *     // outputBuffer contains 200px high JPEG image data,
+ *     // auto-rotated using EXIF Orientation tag
+ *     // info.width and info.height contain the dimensions of the resized image
+ *   });
+ * readableStream.pipe(pipeline);
+ *
+ * @param {Number} [angle=auto] angle of rotation.
+ * @param {Object} [options] - if present, is an Object with optional attributes.
+ * @param {String|Object} [options.background="#000000"] parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function rotate (angle, options) {
+  if (!is.defined(angle)) {
+    this.options.useExifOrientation = true;
+  } else if (is.integer(angle) && !(angle % 90)) {
+    this.options.angle = angle;
+  } else if (is.number(angle)) {
+    this.options.rotationAngle = angle;
+    if (is.object(options) && options.background) {
+      const backgroundColour = color(options.background);
+      this.options.rotationBackground = [
+        backgroundColour.red(),
+        backgroundColour.green(),
+        backgroundColour.blue(),
+        Math.round(backgroundColour.alpha() * 255)
+      ];
+    }
+  } else {
+    throw new Error('Unsupported angle: must be a number.');
+  }
+  return this;
+}
+
+/**
+ * Flip the image about the vertical Y axis. This always occurs after rotation, if any.
+ * The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.
+ * @param {Boolean} [flip=true]
+ * @returns {Sharp}
+ */
+function flip (flip) {
+  this.options.flip = is.bool(flip) ? flip : true;
+  return this;
+}
+
+/**
+ * Flop the image about the horizontal X axis. This always occurs after rotation, if any.
+ * The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.
+ * @param {Boolean} [flop=true]
+ * @returns {Sharp}
+ */
+function flop (flop) {
+  this.options.flop = is.bool(flop) ? flop : true;
+  return this;
+}
+
+/**
+ * Sharpen the image.
+ * When used without parameters, performs a fast, mild sharpen of the output image.
+ * When a `sigma` is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space.
+ * Separate control over the level of sharpening in "flat" and "jagged" areas is available.
+ *
+ * @param {Number} [sigma] - the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+ * @param {Number} [flat=1.0] - the level of sharpening to apply to "flat" areas.
+ * @param {Number} [jagged=2.0] - the level of sharpening to apply to "jagged" areas.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function sharpen (sigma, flat, jagged) {
+  if (!is.defined(sigma)) {
+    // No arguments: default to mild sharpen
+    this.options.sharpenSigma = -1;
+  } else if (is.bool(sigma)) {
+    // Boolean argument: apply mild sharpen?
+    this.options.sharpenSigma = sigma ? -1 : 0;
+  } else if (is.number(sigma) && is.inRange(sigma, 0.01, 10000)) {
+    // Numeric argument: specific sigma
+    this.options.sharpenSigma = sigma;
+    // Control over flat areas
+    if (is.defined(flat)) {
+      if (is.number(flat) && is.inRange(flat, 0, 10000)) {
+        this.options.sharpenFlat = flat;
+      } else {
+        throw new Error('Invalid sharpen level for flat areas (0.0 - 10000.0) ' + flat);
+      }
+    }
+    // Control over jagged areas
+    if (is.defined(jagged)) {
+      if (is.number(jagged) && is.inRange(jagged, 0, 10000)) {
+        this.options.sharpenJagged = jagged;
+      } else {
+        throw new Error('Invalid sharpen level for jagged areas (0.0 - 10000.0) ' + jagged);
+      }
+    }
+  } else {
+    throw new Error('Invalid sharpen sigma (0.01 - 10000) ' + sigma);
+  }
+  return this;
+}
+
+/**
+ * Apply median filter.
+ * When used without parameters the default window is 3x3.
+ * @param {Number} [size=3] square mask size: size x size
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function median (size) {
+  if (!is.defined(size)) {
+    // No arguments: default to 3x3
+    this.options.medianSize = 3;
+  } else if (is.integer(size) && is.inRange(size, 1, 1000)) {
+    // Numeric argument: specific sigma
+    this.options.medianSize = size;
+  } else {
+    throw new Error('Invalid median size ' + size);
+  }
+  return this;
+}
+
+/**
+ * Blur the image.
+ * When used without parameters, performs a fast, mild blur of the output image.
+ * When a `sigma` is provided, performs a slower, more accurate Gaussian blur.
+ * @param {Number} [sigma] a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function blur (sigma) {
+  if (!is.defined(sigma)) {
+    // No arguments: default to mild blur
+    this.options.blurSigma = -1;
+  } else if (is.bool(sigma)) {
+    // Boolean argument: apply mild blur?
+    this.options.blurSigma = sigma ? -1 : 0;
+  } else if (is.number(sigma) && is.inRange(sigma, 0.3, 1000)) {
+    // Numeric argument: specific sigma
+    this.options.blurSigma = sigma;
+  } else {
+    throw new Error('Invalid blur sigma (0.3 - 1000.0) ' + sigma);
+  }
+  return this;
+}
+
+/**
+ * Merge alpha transparency channel, if any, with a background.
+ * @param {Object} [options]
+ * @param {String|Object} [options.background={r: 0, g: 0, b: 0}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black.
+ * @returns {Sharp}
+ */
+function flatten (options) {
+  this.options.flatten = is.bool(options) ? options : true;
+  if (is.object(options)) {
+    this._setColourOption('flattenBackground', options.background);
+  }
+  return this;
+}
+
+/**
+ * Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of `1/gamma`
+ * then increasing the encoding (brighten) post-resize at a factor of `gamma`.
+ * This can improve the perceived brightness of a resized image in non-linear colour spaces.
+ * JPEG and WebP input images will not take advantage of the shrink-on-load performance optimisation
+ * when applying a gamma correction.
+ *
+ * Supply a second argument to use a different output gamma value, otherwise the first value is used in both cases.
+ *
+ * @param {Number} [gamma=2.2] value between 1.0 and 3.0.
+ * @param {Number} [gammaOut] value between 1.0 and 3.0. (optional, defaults to same as `gamma`)
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function gamma (gamma, gammaOut) {
+  if (!is.defined(gamma)) {
+    // Default gamma correction of 2.2 (sRGB)
+    this.options.gamma = 2.2;
+  } else if (is.number(gamma) && is.inRange(gamma, 1, 3)) {
+    this.options.gamma = gamma;
+  } else {
+    throw new Error('Invalid gamma correction (1.0 to 3.0) ' + gamma);
+  }
+  if (!is.defined(gammaOut)) {
+    // Default gamma correction for output is same as input
+    this.options.gammaOut = this.options.gamma;
+  } else if (is.number(gammaOut) && is.inRange(gammaOut, 1, 3)) {
+    this.options.gammaOut = gammaOut;
+  } else {
+    throw new Error('Invalid output gamma correction (1.0 to 3.0) ' + gammaOut);
+  }
+  return this;
+}
+
+/**
+ * Produce the "negative" of the image.
+ * @param {Boolean} [negate=true]
+ * @returns {Sharp}
+ */
+function negate (negate) {
+  this.options.negate = is.bool(negate) ? negate : true;
+  return this;
+}
+
+/**
+ * Enhance output image contrast by stretching its luminance to cover the full dynamic range.
+ * @param {Boolean} [normalise=true]
+ * @returns {Sharp}
+ */
+function normalise (normalise) {
+  this.options.normalise = is.bool(normalise) ? normalise : true;
+  return this;
+}
+
+/**
+ * Alternative spelling of normalise.
+ * @param {Boolean} [normalize=true]
+ * @returns {Sharp}
+ */
+function normalize (normalize) {
+  return this.normalise(normalize);
+}
+
+/**
+ * Convolve the image with the specified kernel.
+ *
+ * @example
+ * sharp(input)
+ *   .convolve({
+ *     width: 3,
+ *     height: 3,
+ *     kernel: [-1, 0, 1, -2, 0, 2, -1, 0, 1]
+ *   })
+ *   .raw()
+ *   .toBuffer(function(err, data, info) {
+ *     // data contains the raw pixel data representing the convolution
+ *     // of the input image with the horizontal Sobel operator
+ *   });
+ *
+ * @param {Object} kernel
+ * @param {Number} kernel.width - width of the kernel in pixels.
+ * @param {Number} kernel.height - width of the kernel in pixels.
+ * @param {Array<Number>} kernel.kernel - Array of length `width*height` containing the kernel values.
+ * @param {Number} [kernel.scale=sum] - the scale of the kernel in pixels.
+ * @param {Number} [kernel.offset=0] - the offset of the kernel in pixels.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function convolve (kernel) {
+  if (!is.object(kernel) || !Array.isArray(kernel.kernel) ||
+      !is.integer(kernel.width) || !is.integer(kernel.height) ||
+      !is.inRange(kernel.width, 3, 1001) || !is.inRange(kernel.height, 3, 1001) ||
+      kernel.height * kernel.width !== kernel.kernel.length
+  ) {
+    // must pass in a kernel
+    throw new Error('Invalid convolution kernel');
+  }
+  // Default scale is sum of kernel values
+  if (!is.integer(kernel.scale)) {
+    kernel.scale = kernel.kernel.reduce(function (a, b) {
+      return a + b;
+    }, 0);
+  }
+  // Clip scale to a minimum value of 1
+  if (kernel.scale < 1) {
+    kernel.scale = 1;
+  }
+  if (!is.integer(kernel.offset)) {
+    kernel.offset = 0;
+  }
+  this.options.convKernel = kernel;
+  return this;
+}
+
+/**
+ * Any pixel value greather than or equal to the threshold value will be set to 255, otherwise it will be set to 0.
+ * @param {Number} [threshold=128] - a value in the range 0-255 representing the level at which the threshold will be applied.
+ * @param {Object} [options]
+ * @param {Boolean} [options.greyscale=true] - convert to single channel greyscale.
+ * @param {Boolean} [options.grayscale=true] - alternative spelling for greyscale.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function threshold (threshold, options) {
+  if (!is.defined(threshold)) {
+    this.options.threshold = 128;
+  } else if (is.bool(threshold)) {
+    this.options.threshold = threshold ? 128 : 0;
+  } else if (is.integer(threshold) && is.inRange(threshold, 0, 255)) {
+    this.options.threshold = threshold;
+  } else {
+    throw new Error('Invalid threshold (0 to 255) ' + threshold);
+  }
+  if (!is.object(options) || options.greyscale === true || options.grayscale === true) {
+    this.options.thresholdGrayscale = true;
+  } else {
+    this.options.thresholdGrayscale = false;
+  }
+  return this;
+}
+
+/**
+ * Perform a bitwise boolean operation with operand image.
+ *
+ * This operation creates an output image where each pixel is the result of
+ * the selected bitwise boolean `operation` between the corresponding pixels of the input images.
+ *
+ * @param {Buffer|String} operand - Buffer containing image data or String containing the path to an image file.
+ * @param {String} operator - one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+ * @param {Object} [options]
+ * @param {Object} [options.raw] - describes operand when using raw pixel data.
+ * @param {Number} [options.raw.width]
+ * @param {Number} [options.raw.height]
+ * @param {Number} [options.raw.channels]
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function boolean (operand, operator, options) {
+  this.options.boolean = this._createInputDescriptor(operand, options);
+  if (is.string(operator) && is.inArray(operator, ['and', 'or', 'eor'])) {
+    this.options.booleanOp = operator;
+  } else {
+    throw new Error('Invalid boolean operator ' + operator);
+  }
+  return this;
+}
+
+/**
+ * Apply the linear formula a * input + b to the image (levels adjustment)
+ * @param {Number} [a=1.0] multiplier
+ * @param {Number} [b=0.0] offset
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function linear (a, b) {
+  if (!is.defined(a)) {
+    this.options.linearA = 1.0;
+  } else if (is.number(a)) {
+    this.options.linearA = a;
+  } else {
+    throw new Error('Invalid linear transform multiplier ' + a);
+  }
+
+  if (!is.defined(b)) {
+    this.options.linearB = 0.0;
+  } else if (is.number(b)) {
+    this.options.linearB = b;
+  } else {
+    throw new Error('Invalid linear transform offset ' + b);
+  }
+
+  return this;
+}
+
+/**
+ * Recomb the image with the specified matrix.
+ *
+ * @example
+ * sharp(input)
+ *   .recomb([
+ *    [0.3588, 0.7044, 0.1368],
+ *    [0.2990, 0.5870, 0.1140],
+ *    [0.2392, 0.4696, 0.0912],
+ *   ])
+ *   .raw()
+ *   .toBuffer(function(err, data, info) {
+ *     // data contains the raw pixel data after applying the recomb
+ *     // With this example input, a sepia filter has been applied
+ *   });
+ *
+ * @param {Array<Array<Number>>} 3x3 Recombination matrix
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function recomb (inputMatrix) {
+  if (!Array.isArray(inputMatrix) || inputMatrix.length !== 3 ||
+      inputMatrix[0].length !== 3 ||
+      inputMatrix[1].length !== 3 ||
+      inputMatrix[2].length !== 3
+  ) {
+    // must pass in a kernel
+    throw new Error('Invalid Recomb Matrix');
+  }
+  this.options.recombMatrix = [
+    inputMatrix[0][0], inputMatrix[0][1], inputMatrix[0][2],
+    inputMatrix[1][0], inputMatrix[1][1], inputMatrix[1][2],
+    inputMatrix[2][0], inputMatrix[2][1], inputMatrix[2][2]
+  ].map(Number);
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with operation-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    rotate,
+    flip,
+    flop,
+    sharpen,
+    median,
+    blur,
+    flatten,
+    gamma,
+    negate,
+    normalise,
+    normalize,
+    convolve,
+    threshold,
+    boolean,
+    linear,
+    recomb
+  });
+};

lib/output.js

@@ -0,0 +1,732 @@
+'use strict';
+
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Write output image data to a file.
+ *
+ * If an explicit output format is not selected, it will be inferred from the extension,
+ * with JPEG, PNG, WebP, TIFF, DZI, and libvips' V format supported.
+ * Note that raw pixel data is only supported for buffer output.
+ *
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * @example
+ * sharp(input)
+ *   .toFile('output.png', (err, info) => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toFile('output.png')
+ *   .then(info => { ... })
+ *   .catch(err => { ... });
+ *
+ * @param {String} fileOut - the path to write the image data to.
+ * @param {Function} [callback] - called on completion with two arguments `(err, info)`.
+ * `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+ * `channels` and `premultiplied` (indicating if premultiplication was used).
+ * When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+ * @returns {Promise<Object>} - when no callback is provided
+ * @throws {Error} Invalid parameters
+ */
+function toFile (fileOut, callback) {
+  if (!fileOut || fileOut.length === 0) {
+    const errOutputInvalid = new Error('Missing output file path');
+    if (is.fn(callback)) {
+      callback(errOutputInvalid);
+    } else {
+      return Promise.reject(errOutputInvalid);
+    }
+  } else {
+    if (this.options.input.file === fileOut) {
+      const errOutputIsInput = new Error('Cannot use same file for input and output');
+      if (is.fn(callback)) {
+        callback(errOutputIsInput);
+      } else {
+        return Promise.reject(errOutputIsInput);
+      }
+    } else {
+      this.options.fileOut = fileOut;
+      return this._pipeline(callback);
+    }
+  }
+  return this;
+}
+
+/**
+ * Write output to a Buffer.
+ * JPEG, PNG, WebP, TIFF and RAW output are supported.
+ * By default, the format will match the input image, except GIF and SVG input which become PNG output.
+ *
+ * `callback`, if present, gets three arguments `(err, data, info)` where:
+ * - `err` is an error, if any.
+ * - `data` is the output image data.
+ * - `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+ * `channels` and `premultiplied` (indicating if premultiplication was used).
+ * When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+ *
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer((err, data, info) => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer()
+ *   .then(data => { ... })
+ *   .catch(err => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer({ resolveWithObject: true })
+ *   .then(({ data, info }) => { ... })
+ *   .catch(err => { ... });
+ *
+ * @param {Object} [options]
+ * @param {Boolean} [options.resolveWithObject] Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
+ * @param {Function} [callback]
+ * @returns {Promise<Buffer>} - when no callback is provided
+ */
+function toBuffer (options, callback) {
+  if (is.object(options)) {
+    if (is.bool(options.resolveWithObject)) {
+      this.options.resolveWithObject = options.resolveWithObject;
+    }
+  }
+  return this._pipeline(is.fn(options) ? options : callback);
+}
+
+/**
+ * Include all metadata (EXIF, XMP, IPTC) from the input image in the output image.
+ * The default behaviour, when `withMetadata` is not used, is to strip all metadata and convert to the device-independent sRGB colour space.
+ * This will also convert to and add a web-friendly sRGB ICC profile.
+ *
+ * @example
+ * sharp('input.jpg')
+ *   .withMetadata()
+ *   .toFile('output-with-metadata.jpg')
+ *   .then(info => { ... });
+ *
+ * @param {Object} [withMetadata]
+ * @param {Number} [withMetadata.orientation] value between 1 and 8, used to update the EXIF `Orientation` tag.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function withMetadata (withMetadata) {
+  this.options.withMetadata = is.bool(withMetadata) ? withMetadata : true;
+  if (is.object(withMetadata)) {
+    if (is.defined(withMetadata.orientation)) {
+      if (is.integer(withMetadata.orientation) && is.inRange(withMetadata.orientation, 1, 8)) {
+        this.options.withMetadataOrientation = withMetadata.orientation;
+      } else {
+        throw new Error('Invalid orientation (1 to 8) ' + withMetadata.orientation);
+      }
+    }
+  }
+  return this;
+}
+
+/**
+ * Use these JPEG options for output image.
+ *
+ * @example
+ * // Convert any input to very high quality JPEG output
+ * const data = await sharp(input)
+ *   .jpeg({
+ *     quality: 100,
+ *     chromaSubsampling: '4:4:4'
+ *   })
+ *   .toBuffer();
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Boolean} [options.progressive=false] - use progressive (interlace) scan
+ * @param {String} [options.chromaSubsampling='4:2:0'] - set to '4:4:4' to prevent chroma subsampling when quality <= 90
+ * @param {Boolean} [options.trellisQuantisation=false] - apply trellis quantisation, requires mozjpeg
+ * @param {Boolean} [options.overshootDeringing=false] - apply overshoot deringing, requires mozjpeg
+ * @param {Boolean} [options.optimiseScans=false] - optimise progressive scans, forces progressive, requires mozjpeg
+ * @param {Boolean} [options.optimizeScans=false] - alternative spelling of optimiseScans
+ * @param {Boolean} [options.optimiseCoding=true] - optimise Huffman coding tables
+ * @param {Boolean} [options.optimizeCoding=true] - alternative spelling of optimiseCoding
+ * @param {Number} [options.quantisationTable=0] - quantization table to use, integer 0-8, requires mozjpeg
+ * @param {Number} [options.quantizationTable=0] - alternative spelling of quantisationTable
+ * @param {Boolean} [options.force=true] - force JPEG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function jpeg (options) {
+  if (is.object(options)) {
+    if (is.defined(options.quality)) {
+      if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+        this.options.jpegQuality = options.quality;
+      } else {
+        throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+      }
+    }
+    if (is.defined(options.progressive)) {
+      this._setBooleanOption('jpegProgressive', options.progressive);
+    }
+    if (is.defined(options.chromaSubsampling)) {
+      if (is.string(options.chromaSubsampling) && is.inArray(options.chromaSubsampling, ['4:2:0', '4:4:4'])) {
+        this.options.jpegChromaSubsampling = options.chromaSubsampling;
+      } else {
+        throw new Error('Invalid chromaSubsampling (4:2:0, 4:4:4) ' + options.chromaSubsampling);
+      }
+    }
+    const trellisQuantisation = is.bool(options.trellisQuantization) ? options.trellisQuantization : options.trellisQuantisation;
+    if (is.defined(trellisQuantisation)) {
+      this._setBooleanOption('jpegTrellisQuantisation', trellisQuantisation);
+    }
+    if (is.defined(options.overshootDeringing)) {
+      this._setBooleanOption('jpegOvershootDeringing', options.overshootDeringing);
+    }
+    const optimiseScans = is.bool(options.optimizeScans) ? options.optimizeScans : options.optimiseScans;
+    if (is.defined(optimiseScans)) {
+      this._setBooleanOption('jpegOptimiseScans', optimiseScans);
+      if (optimiseScans) {
+        this.options.jpegProgressive = true;
+      }
+    }
+    const optimiseCoding = is.bool(options.optimizeCoding) ? options.optimizeCoding : options.optimiseCoding;
+    if (is.defined(optimiseCoding)) {
+      this._setBooleanOption('jpegOptimiseCoding', optimiseCoding);
+    }
+    const quantisationTable = is.number(options.quantizationTable) ? options.quantizationTable : options.quantisationTable;
+    if (is.defined(quantisationTable)) {
+      if (is.integer(quantisationTable) && is.inRange(quantisationTable, 0, 8)) {
+        this.options.jpegQuantisationTable = quantisationTable;
+      } else {
+        throw new Error('Invalid quantisation table (integer, 0-8) ' + quantisationTable);
+      }
+    }
+  }
+  return this._updateFormatOut('jpeg', options);
+}
+
+/**
+ * Use these PNG options for output image.
+ *
+ * PNG output is always full colour at 8 or 16 bits per pixel.
+ * Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.
+ *
+ * @example
+ * // Convert any input to PNG output
+ * const data = await sharp(input)
+ *   .png()
+ *   .toBuffer();
+ *
+ * @param {Object} [options]
+ * @param {Boolean} [options.progressive=false] - use progressive (interlace) scan
+ * @param {Number} [options.compressionLevel=9] - zlib compression level, 0-9
+ * @param {Boolean} [options.adaptiveFiltering=false] - use adaptive row filtering
+ * @param {Boolean} [options.palette=false] - quantise to a palette-based image with alpha transparency support, requires libimagequant
+ * @param {Number} [options.quality=100] - use the lowest number of colours needed to achieve given quality, requires libimagequant
+ * @param {Number} [options.colours=256] - maximum number of palette entries, requires libimagequant
+ * @param {Number} [options.colors=256] - alternative spelling of `options.colours`, requires libimagequant
+ * @param {Number} [options.dither=1.0] - level of Floyd-Steinberg error diffusion, requires libimagequant
+ * @param {Boolean} [options.force=true] - force PNG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function png (options) {
+  if (is.object(options)) {
+    if (is.defined(options.progressive)) {
+      this._setBooleanOption('pngProgressive', options.progressive);
+    }
+    if (is.defined(options.compressionLevel)) {
+      if (is.integer(options.compressionLevel) && is.inRange(options.compressionLevel, 0, 9)) {
+        this.options.pngCompressionLevel = options.compressionLevel;
+      } else {
+        throw new Error('Invalid compressionLevel (integer, 0-9) ' + options.compressionLevel);
+      }
+    }
+    if (is.defined(options.adaptiveFiltering)) {
+      this._setBooleanOption('pngAdaptiveFiltering', options.adaptiveFiltering);
+    }
+    if (is.defined(options.palette)) {
+      this._setBooleanOption('pngPalette', options.palette);
+      if (this.options.pngPalette) {
+        if (is.defined(options.quality)) {
+          if (is.integer(options.quality) && is.inRange(options.quality, 0, 100)) {
+            this.options.pngQuality = options.quality;
+          } else {
+            throw is.invalidParameterError('quality', 'integer between 0 and 100', options.quality);
+          }
+        }
+        const colours = options.colours || options.colors;
+        if (is.defined(colours)) {
+          if (is.integer(colours) && is.inRange(colours, 2, 256)) {
+            this.options.pngColours = colours;
+          } else {
+            throw is.invalidParameterError('colours', 'integer between 2 and 256', colours);
+          }
+        }
+        if (is.defined(options.dither)) {
+          if (is.number(options.dither) && is.inRange(options.dither, 0, 1)) {
+            this.options.pngDither = options.dither;
+          } else {
+            throw is.invalidParameterError('dither', 'number between 0.0 and 1.0', options.dither);
+          }
+        }
+      }
+    }
+  }
+  return this._updateFormatOut('png', options);
+}
+
+/**
+ * Use these WebP options for output image.
+ *
+ * @example
+ * // Convert any input to lossless WebP output
+ * const data = await sharp(input)
+ *   .webp({ lossless: true })
+ *   .toBuffer();
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Number} [options.alphaQuality=100] - quality of alpha layer, integer 0-100
+ * @param {Boolean} [options.lossless=false] - use lossless compression mode
+ * @param {Boolean} [options.nearLossless=false] - use near_lossless compression mode
+ * @param {Boolean} [options.force=true] - force WebP output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function webp (options) {
+  if (is.object(options) && is.defined(options.quality)) {
+    if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+      this.options.webpQuality = options.quality;
+    } else {
+      throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+    }
+  }
+  if (is.object(options) && is.defined(options.alphaQuality)) {
+    if (is.integer(options.alphaQuality) && is.inRange(options.alphaQuality, 0, 100)) {
+      this.options.webpAlphaQuality = options.alphaQuality;
+    } else {
+      throw new Error('Invalid webp alpha quality (integer, 0-100) ' + options.alphaQuality);
+    }
+  }
+  if (is.object(options) && is.defined(options.lossless)) {
+    this._setBooleanOption('webpLossless', options.lossless);
+  }
+  if (is.object(options) && is.defined(options.nearLossless)) {
+    this._setBooleanOption('webpNearLossless', options.nearLossless);
+  }
+  return this._updateFormatOut('webp', options);
+}
+
+/**
+ * Use these TIFF options for output image.
+ *
+ * @example
+ * // Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
+ * sharp('input.svg')
+ *   .tiff({
+ *     compression: 'lzw',
+ *     squash: true
+ *   })
+ *   .toFile('1-bpp-output.tiff')
+ *   .then(info => { ... });
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Boolean} [options.force=true] - force TIFF output, otherwise attempt to use input format
+ * @param {Boolean} [options.compression='jpeg'] - compression options: lzw, deflate, jpeg, ccittfax4
+ * @param {Boolean} [options.predictor='horizontal'] - compression predictor options: none, horizontal, float
+ * @param {Boolean} [options.pyramid=false] - write an image pyramid
+ * @param {Boolean} [options.tile=false] - write a tiled tiff
+ * @param {Boolean} [options.tileWidth=256] - horizontal tile size
+ * @param {Boolean} [options.tileHeight=256] - vertical tile size
+ * @param {Number} [options.xres=1.0] - horizontal resolution in pixels/mm
+ * @param {Number} [options.yres=1.0] - vertical resolution in pixels/mm
+ * @param {Boolean} [options.squash=false] - squash 8-bit images down to 1 bit
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function tiff (options) {
+  if (is.object(options)) {
+    if (is.defined(options.quality)) {
+      if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+        this.options.tiffQuality = options.quality;
+      } else {
+        throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+      }
+    }
+    if (is.defined(options.squash)) {
+      if (is.bool(options.squash)) {
+        this.options.tiffSquash = options.squash;
+      } else {
+        throw new Error('Invalid Value for squash ' + options.squash + ' Only Boolean Values allowed for options.squash.');
+      }
+    }
+    // tiling
+    if (is.defined(options.tile)) {
+      if (is.bool(options.tile)) {
+        this.options.tiffTile = options.tile;
+      } else {
+        throw new Error('Invalid Value for tile ' + options.tile + ' Only Boolean values allowed for options.tile');
+      }
+    }
+    if (is.defined(options.tileWidth)) {
+      if (is.number(options.tileWidth) && options.tileWidth > 0) {
+        this.options.tiffTileWidth = options.tileWidth;
+      } else {
+        throw new Error('Invalid Value for tileWidth ' + options.tileWidth + ' Only positive numeric values allowed for options.tileWidth');
+      }
+    }
+    if (is.defined(options.tileHeight)) {
+      if (is.number(options.tileHeight) && options.tileHeight > 0) {
+        this.options.tiffTileHeight = options.tileHeight;
+      } else {
+        throw new Error('Invalid Value for tileHeight ' + options.tileHeight + ' Only positive numeric values allowed for options.tileHeight');
+      }
+    }
+    // pyramid
+    if (is.defined(options.pyramid)) {
+      if (is.bool(options.pyramid)) {
+        this.options.tiffPyramid = options.pyramid;
+      } else {
+        throw new Error('Invalid Value for pyramid ' + options.pyramid + ' Only Boolean values allowed for options.pyramid');
+      }
+    }
+    // resolution
+    if (is.defined(options.xres)) {
+      if (is.number(options.xres)) {
+        this.options.tiffXres = options.xres;
+      } else {
+        throw new Error('Invalid Value for xres ' + options.xres + ' Only numeric values allowed for options.xres');
+      }
+    }
+    if (is.defined(options.yres)) {
+      if (is.number(options.yres)) {
+        this.options.tiffYres = options.yres;
+      } else {
+        throw new Error('Invalid Value for yres ' + options.yres + ' Only numeric values allowed for options.yres');
+      }
+    }
+    // compression
+    if (is.defined(options.compression)) {
+      if (is.string(options.compression) && is.inArray(options.compression, ['lzw', 'deflate', 'jpeg', 'ccittfax4', 'none'])) {
+        this.options.tiffCompression = options.compression;
+      } else {
+        const message = `Invalid compression option "${options.compression}". Should be one of: lzw, deflate, jpeg, ccittfax4, none`;
+        throw new Error(message);
+      }
+    }
+    // predictor
+    if (is.defined(options.predictor)) {
+      if (is.string(options.predictor) && is.inArray(options.predictor, ['none', 'horizontal', 'float'])) {
+        this.options.tiffPredictor = options.predictor;
+      } else {
+        const message = `Invalid predictor option "${options.predictor}". Should be one of: none, horizontal, float`;
+        throw new Error(message);
+      }
+    }
+  }
+  return this._updateFormatOut('tiff', options);
+}
+
+/**
+ * Force output to be raw, uncompressed uint8 pixel data.
+ *
+ * @example
+ * // Extract raw RGB pixel data from JPEG input
+ * const { data, info } = await sharp('input.jpg')
+ *   .raw()
+ *   .toBuffer({ resolveWithObject: true });
+ *
+ * @returns {Sharp}
+ */
+function raw () {
+  return this._updateFormatOut('raw');
+}
+
+/**
+ * Force output to a given format.
+ *
+ * @example
+ * // Convert any input to PNG output
+ * const data = await sharp(input)
+ *   .toFormat('png')
+ *   .toBuffer();
+ *
+ * @param {(String|Object)} format - as a String or an Object with an 'id' attribute
+ * @param {Object} options - output options
+ * @returns {Sharp}
+ * @throws {Error} unsupported format or options
+ */
+function toFormat (format, options) {
+  if (is.object(format) && is.string(format.id)) {
+    format = format.id;
+  }
+  if (format === 'jpg') format = 'jpeg';
+  if (!is.inArray(format, ['jpeg', 'png', 'webp', 'tiff', 'raw'])) {
+    throw new Error('Unsupported output format ' + format);
+  }
+  return this[format](options);
+}
+
+/**
+ * Use tile-based deep zoom (image pyramid) output.
+ * Set the format and options for tile images via the `toFormat`, `jpeg`, `png` or `webp` functions.
+ * Use a `.zip` or `.szi` file extension with `toFile` to write to a compressed archive file format.
+ *
+ * Warning: multiple sharp instances concurrently producing tile output can expose a possible race condition in some versions of libgsf.
+ *
+ * @example
+ *  sharp('input.tiff')
+ *   .png()
+ *   .tile({
+ *     size: 512
+ *   })
+ *   .toFile('output.dz', function(err, info) {
+ *     // output.dzi is the Deep Zoom XML definition
+ *     // output_files contains 512x512 tiles grouped by zoom level
+ *   });
+ *
+ * @param {Object} [tile]
+ * @param {Number} [tile.size=256] tile size in pixels, a value between 1 and 8192.
+ * @param {Number} [tile.overlap=0] tile overlap in pixels, a value between 0 and 8192.
+ * @param {Number} [tile.angle=0] tile angle of rotation, must be a multiple of 90.
+ * @param {String} [tile.depth] how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
+ * @param {String} [tile.container='fs'] tile container, with value `fs` (filesystem) or `zip` (compressed file).
+ * @param {String} [tile.layout='dz'] filesystem layout, possible values are `dz`, `zoomify` or `google`.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function tile (tile) {
+  if (is.object(tile)) {
+    // Size of square tiles, in pixels
+    if (is.defined(tile.size)) {
+      if (is.integer(tile.size) && is.inRange(tile.size, 1, 8192)) {
+        this.options.tileSize = tile.size;
+      } else {
+        throw new Error('Invalid tile size (1 to 8192) ' + tile.size);
+      }
+    }
+    // Overlap of tiles, in pixels
+    if (is.defined(tile.overlap)) {
+      if (is.integer(tile.overlap) && is.inRange(tile.overlap, 0, 8192)) {
+        if (tile.overlap > this.options.tileSize) {
+          throw new Error('Tile overlap ' + tile.overlap + ' cannot be larger than tile size ' + this.options.tileSize);
+        }
+        this.options.tileOverlap = tile.overlap;
+      } else {
+        throw new Error('Invalid tile overlap (0 to 8192) ' + tile.overlap);
+      }
+    }
+    // Container
+    if (is.defined(tile.container)) {
+      if (is.string(tile.container) && is.inArray(tile.container, ['fs', 'zip'])) {
+        this.options.tileContainer = tile.container;
+      } else {
+        throw new Error('Invalid tile container ' + tile.container);
+      }
+    }
+    // Layout
+    if (is.defined(tile.layout)) {
+      if (is.string(tile.layout) && is.inArray(tile.layout, ['dz', 'google', 'zoomify'])) {
+        this.options.tileLayout = tile.layout;
+      } else {
+        throw new Error('Invalid tile layout ' + tile.layout);
+      }
+    }
+
+    // Angle of rotation,
+    if (is.defined(tile.angle)) {
+      if (is.integer(tile.angle) && !(tile.angle % 90)) {
+        this.options.tileAngle = tile.angle;
+      } else {
+        throw new Error('Unsupported angle: angle must be a positive/negative multiple of 90 ' + tile.angle);
+      }
+    }
+
+    // Depth of tiles
+    if (is.defined(tile.depth)) {
+      if (is.string(tile.depth) && is.inArray(tile.depth, ['onepixel', 'onetile', 'one'])) {
+        this.options.tileDepth = tile.depth;
+      } else {
+        throw new Error("Invalid tile depth '" + tile.depth + "', should be one of 'onepixel', 'onetile' or 'one'");
+      }
+    }
+  }
+  // Format
+  if (is.inArray(this.options.formatOut, ['jpeg', 'png', 'webp'])) {
+    this.options.tileFormat = this.options.formatOut;
+  } else if (this.options.formatOut !== 'input') {
+    throw new Error('Invalid tile format ' + this.options.formatOut);
+  }
+
+  return this._updateFormatOut('dz');
+}
+
+/**
+ * Update the output format unless options.force is false,
+ * in which case revert to input format.
+ * @private
+ * @param {String} formatOut
+ * @param {Object} [options]
+ * @param {Boolean} [options.force=true] - force output format, otherwise attempt to use input format
+ * @returns {Sharp}
+ */
+function _updateFormatOut (formatOut, options) {
+  if (!(is.object(options) && options.force === false)) {
+    this.options.formatOut = formatOut;
+  }
+  return this;
+}
+
+/**
+ * Update a Boolean attribute of the this.options Object.
+ * @private
+ * @param {String} key
+ * @param {Boolean} val
+ * @throws {Error} Invalid key
+ */
+function _setBooleanOption (key, val) {
+  if (is.bool(val)) {
+    this.options[key] = val;
+  } else {
+    throw new Error('Invalid ' + key + ' (boolean) ' + val);
+  }
+}
+
+/**
+ * Called by a WriteableStream to notify us it is ready for data.
+ * @private
+ */
+function _read () {
+  if (!this.options.streamOut) {
+    this.options.streamOut = true;
+    this._pipeline();
+  }
+}
+
+/**
+ * Invoke the C++ image processing pipeline
+ * Supports callback, stream and promise variants
+ * @private
+ */
+function _pipeline (callback) {
+  const that = this;
+  if (typeof callback === 'function') {
+    // output=file/buffer
+    if (this._isStreamInput()) {
+      // output=file/buffer, input=stream
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.pipeline(that.options, callback);
+      });
+    } else {
+      // output=file/buffer, input=file/buffer
+      sharp.pipeline(this.options, callback);
+    }
+    return this;
+  } else if (this.options.streamOut) {
+    // output=stream
+    if (this._isStreamInput()) {
+      // output=stream, input=stream
+      if (this.streamInFinished) {
+        this._flattenBufferIn();
+        sharp.pipeline(this.options, function (err, data, info) {
+          if (err) {
+            that.emit('error', err);
+          } else {
+            that.emit('info', info);
+            that.push(data);
+          }
+          that.push(null);
+        });
+      } else {
+        this.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.pipeline(that.options, function (err, data, info) {
+            if (err) {
+              that.emit('error', err);
+            } else {
+              that.emit('info', info);
+              that.push(data);
+            }
+            that.push(null);
+          });
+        });
+      }
+    } else {
+      // output=stream, input=file/buffer
+      sharp.pipeline(this.options, function (err, data, info) {
+        if (err) {
+          that.emit('error', err);
+        } else {
+          that.emit('info', info);
+          that.push(data);
+        }
+        that.push(null);
+      });
+    }
+    return this;
+  } else {
+    // output=promise
+    if (this._isStreamInput()) {
+      // output=promise, input=stream
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.pipeline(that.options, function (err, data, info) {
+            if (err) {
+              reject(err);
+            } else {
+              if (that.options.resolveWithObject) {
+                resolve({ data: data, info: info });
+              } else {
+                resolve(data);
+              }
+            }
+          });
+        });
+      });
+    } else {
+      // output=promise, input=file/buffer
+      return new Promise(function (resolve, reject) {
+        sharp.pipeline(that.options, function (err, data, info) {
+          if (err) {
+            reject(err);
+          } else {
+            if (that.options.resolveWithObject) {
+              resolve({ data: data, info: info });
+            } else {
+              resolve(data);
+            }
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Decorate the Sharp prototype with output-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    // Public
+    toFile,
+    toBuffer,
+    withMetadata,
+    jpeg,
+    png,
+    webp,
+    tiff,
+    raw,
+    toFormat,
+    tile,
+    // Private
+    _updateFormatOut,
+    _setBooleanOption,
+    _read,
+    _pipeline
+  });
+};

lib/platform.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const detectLibc = require('detect-libc');
+
+const env = process.env;
+
+module.exports = function () {
+  const arch = env.npm_config_arch || process.arch;
+  const platform = env.npm_config_platform || process.platform;
+  const libc = (platform === 'linux' && detectLibc.isNonGlibcLinux) ? detectLibc.family : '';
+
+  const platformId = [`${platform}${libc}`];
+
+  if (arch === 'arm') {
+    platformId.push(`armv${env.npm_config_arm_version || process.config.variables.arm_version || '6'}`);
+  } else if (arch === 'arm64') {
+    platformId.push(`arm64v${env.npm_config_arm_version || '8'}`);
+  } else {
+    platformId.push(arch);
+  }
+
+  return platformId.join('-');
+};

lib/resize.js

@@ -0,0 +1,397 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Weighting to apply when using contain/cover fit.
+ * @member
+ * @private
+ */
+const gravity = {
+  center: 0,
+  centre: 0,
+  north: 1,
+  east: 2,
+  south: 3,
+  west: 4,
+  northeast: 5,
+  southeast: 6,
+  southwest: 7,
+  northwest: 8
+};
+
+/**
+ * Position to apply when using contain/cover fit.
+ * @member
+ * @private
+ */
+const position = {
+  top: 1,
+  right: 2,
+  bottom: 3,
+  left: 4,
+  'right top': 5,
+  'right bottom': 6,
+  'left bottom': 7,
+  'left top': 8
+};
+
+/**
+ * Strategies for automagic cover behaviour.
+ * @member
+ * @private
+ */
+const strategy = {
+  entropy: 16,
+  attention: 17
+};
+
+/**
+ * Reduction kernels.
+ * @member
+ * @private
+ */
+const kernel = {
+  nearest: 'nearest',
+  cubic: 'cubic',
+  mitchell: 'mitchell',
+  lanczos2: 'lanczos2',
+  lanczos3: 'lanczos3'
+};
+
+/**
+ * Methods by which an image can be resized to fit the provided dimensions.
+ * @member
+ * @private
+ */
+const fit = {
+  contain: 'contain',
+  cover: 'cover',
+  fill: 'fill',
+  inside: 'inside',
+  outside: 'outside'
+};
+
+/**
+ * Map external fit property to internal canvas property.
+ * @member
+ * @private
+ */
+const mapFitToCanvas = {
+  contain: 'embed',
+  cover: 'crop',
+  fill: 'ignore_aspect',
+  inside: 'max',
+  outside: 'min'
+};
+
+/**
+ * Resize image to `width`, `height` or `width x height`.
+ *
+ * When both a `width` and `height` are provided, the possible methods by which the image should **fit** these are:
+ * - `cover`: Crop to cover both provided dimensions (the default).
+ * - `contain`: Embed within both provided dimensions.
+ * - `fill`: Ignore the aspect ratio of the input and stretch to both provided dimensions.
+ * - `inside`: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to both those specified.
+ * - `outside`: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to both those specified.
+ * Some of these values are based on the [object-fit](https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit) CSS property.
+ *
+ * When using a `fit` of `cover` or `contain`, the default **position** is `centre`. Other options are:
+ * - `sharp.position`: `top`, `right top`, `right`, `right bottom`, `bottom`, `left bottom`, `left`, `left top`.
+ * - `sharp.gravity`: `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` or `centre`.
+ * - `sharp.strategy`: `cover` only, dynamically crop using either the `entropy` or `attention` strategy.
+ * Some of these values are based on the [object-position](https://developer.mozilla.org/en-US/docs/Web/CSS/object-position) CSS property.
+ *
+ * The experimental strategy-based approach resizes so one dimension is at its target length
+ * then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.
+ * - `entropy`: focus on the region with the highest [Shannon entropy](https://en.wikipedia.org/wiki/Entropy_%28information_theory%29).
+ * - `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.
+ *
+ * Possible interpolation kernels are:
+ * - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
+ * - `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
+ * - `mitchell`: Use a [Mitchell-Netravali spline](https://www.cs.utexas.edu/~fussell/courses/cs384g-fall2013/lectures/mitchell/Mitchell.pdf).
+ * - `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
+ * - `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
+ *
+ * @example
+ * sharp(input)
+ *   .resize({ width: 100 })
+ *   .toBuffer()
+ *   .then(data => {
+ *     // 100 pixels wide, auto-scaled height
+ *   });
+ *
+ * @example
+ * sharp(input)
+ *   .resize({ height: 100 })
+ *   .toBuffer()
+ *   .then(data => {
+ *     // 100 pixels high, auto-scaled width
+ *   });
+ *
+ * @example
+ * sharp(input)
+ *   .resize(200, 300, {
+ *     kernel: sharp.kernel.nearest,
+ *     fit: 'contain',
+ *     position: 'right top',
+ *     background: { r: 255, g: 255, b: 255, alpha: 0.5 }
+ *   })
+ *   .toFile('output.png')
+ *   .then(() => {
+ *     // output.png is a 200 pixels wide and 300 pixels high image
+ *     // containing a nearest-neighbour scaled version
+ *     // contained within the north-east corner of a semi-transparent white canvas
+ *   });
+ *
+ * @example
+ * const transformer = sharp()
+ *   .resize({
+ *     width: 200,
+ *     height: 200,
+ *     fit: sharp.fit.cover,
+ *     position: sharp.strategy.entropy
+ *   });
+ * // Read image data from readableStream
+ * // Write 200px square auto-cropped image data to writableStream
+ * readableStream
+ *   .pipe(transformer)
+ *   .pipe(writableStream);
+ *
+ * @example
+ * sharp(input)
+ *   .resize(200, 200, {
+ *     fit: sharp.fit.inside,
+ *     withoutEnlargement: true
+ *   })
+ *   .toFormat('jpeg')
+ *   .toBuffer()
+ *   .then(function(outputBuffer) {
+ *     // outputBuffer contains JPEG image data
+ *     // no wider and no higher than 200 pixels
+ *     // and no larger than the input image
+ *   });
+ *
+ * @param {Number} [width] - pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
+ * @param {Number} [height] - pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
+ * @param {Object} [options]
+ * @param {String} [options.width] - alternative means of specifying `width`. If both are present this take priority.
+ * @param {String} [options.height] - alternative means of specifying `height`. If both are present this take priority.
+ * @param {String} [options.fit='cover'] - how the image should be resized to fit both provided dimensions, one of `cover`, `contain`, `fill`, `inside` or `outside`.
+ * @param {String} [options.position='centre'] - position, gravity or strategy to use when `fit` is `cover` or `contain`.
+ * @param {String|Object} [options.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour when using a `fit` of `contain`, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
+ * @param {String} [options.kernel='lanczos3'] - the kernel to use for image reduction.
+ * @param {Boolean} [options.withoutEnlargement=false] - do not enlarge if the width *or* height are already less than the specified dimensions, equivalent to GraphicsMagick's `>` geometry option.
+ * @param {Boolean} [options.fastShrinkOnLoad=true] - take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function resize (width, height, options) {
+  if (is.defined(width)) {
+    if (is.object(width) && !is.defined(options)) {
+      options = width;
+    } else if (is.integer(width) && width > 0) {
+      this.options.width = width;
+    } else {
+      throw is.invalidParameterError('width', 'positive integer', width);
+    }
+  } else {
+    this.options.width = -1;
+  }
+  if (is.defined(height)) {
+    if (is.integer(height) && height > 0) {
+      this.options.height = height;
+    } else {
+      throw is.invalidParameterError('height', 'positive integer', height);
+    }
+  } else {
+    this.options.height = -1;
+  }
+  if (is.object(options)) {
+    // Width
+    if (is.integer(options.width) && options.width > 0) {
+      this.options.width = options.width;
+    }
+    // Height
+    if (is.integer(options.height) && options.height > 0) {
+      this.options.height = options.height;
+    }
+    // Fit
+    if (is.defined(options.fit)) {
+      const canvas = mapFitToCanvas[options.fit];
+      if (is.string(canvas)) {
+        this.options.canvas = canvas;
+      } else {
+        throw is.invalidParameterError('fit', 'valid fit', options.fit);
+      }
+    }
+    // Position
+    if (is.defined(options.position)) {
+      const pos = is.integer(options.position)
+        ? options.position
+        : strategy[options.position] || position[options.position] || gravity[options.position];
+      if (is.integer(pos) && (is.inRange(pos, 0, 8) || is.inRange(pos, 16, 17))) {
+        this.options.position = pos;
+      } else {
+        throw is.invalidParameterError('position', 'valid position/gravity/strategy', options.position);
+      }
+    }
+    // Background
+    if (is.defined(options.background)) {
+      this._setColourOption('resizeBackground', options.background);
+    }
+    // Kernel
+    if (is.defined(options.kernel)) {
+      if (is.string(kernel[options.kernel])) {
+        this.options.kernel = kernel[options.kernel];
+      } else {
+        throw is.invalidParameterError('kernel', 'valid kernel name', options.kernel);
+      }
+    }
+    // Without enlargement
+    if (is.defined(options.withoutEnlargement)) {
+      this._setBooleanOption('withoutEnlargement', options.withoutEnlargement);
+    }
+    // Shrink on load
+    if (is.defined(options.fastShrinkOnLoad)) {
+      this._setBooleanOption('fastShrinkOnLoad', options.fastShrinkOnLoad);
+    }
+  }
+  return this;
+}
+
+/**
+ * Extends/pads the edges of the image with the provided background colour.
+ * This operation will always occur after resizing and extraction, if any.
+ *
+ * @example
+ * // Resize to 140 pixels wide, then add 10 transparent pixels
+ * // to the top, left and right edges and 20 to the bottom edge
+ * sharp(input)
+ *   .resize(140)
+ *   .extend({
+ *     top: 10,
+ *     bottom: 20,
+ *     left: 10,
+ *     right: 10,
+ *     background: { r: 0, g: 0, b: 0, alpha: 0 }
+ *   })
+ *   ...
+ *
+ * @param {(Number|Object)} extend - single pixel count to add to all edges or an Object with per-edge counts
+ * @param {Number} [extend.top]
+ * @param {Number} [extend.left]
+ * @param {Number} [extend.bottom]
+ * @param {Number} [extend.right]
+ * @param {String|Object} [extend.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+*/
+function extend (extend) {
+  if (is.integer(extend) && extend > 0) {
+    this.options.extendTop = extend;
+    this.options.extendBottom = extend;
+    this.options.extendLeft = extend;
+    this.options.extendRight = extend;
+  } else if (
+    is.object(extend) &&
+    is.integer(extend.top) && extend.top >= 0 &&
+    is.integer(extend.bottom) && extend.bottom >= 0 &&
+    is.integer(extend.left) && extend.left >= 0 &&
+    is.integer(extend.right) && extend.right >= 0
+  ) {
+    this.options.extendTop = extend.top;
+    this.options.extendBottom = extend.bottom;
+    this.options.extendLeft = extend.left;
+    this.options.extendRight = extend.right;
+    this._setColourOption('extendBackground', extend.background);
+  } else {
+    throw new Error('Invalid edge extension ' + extend);
+  }
+  return this;
+}
+
+/**
+ * Extract a region of the image.
+ *
+ * - Use `extract` before `resize` for pre-resize extraction.
+ * - Use `extract` after `resize` for post-resize extraction.
+ * - Use `extract` before and after for both.
+ *
+ * @example
+ * sharp(input)
+ *   .extract({ left: left, top: top, width: width, height: height })
+ *   .toFile(output, function(err) {
+ *     // Extract a region of the input image, saving in the same format.
+ *   });
+ * @example
+ * sharp(input)
+ *   .extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
+ *   .resize(width, height)
+ *   .extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
+ *   .toFile(output, function(err) {
+ *     // Extract a region, resize, then extract from the resized image
+ *   });
+ *
+ * @param {Object} options
+ * @param {Number} options.left - zero-indexed offset from left edge
+ * @param {Number} options.top - zero-indexed offset from top edge
+ * @param {Number} options.width - dimension of extracted image
+ * @param {Number} options.height - dimension of extracted image
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function extract (options) {
+  const suffix = this.options.width === -1 && this.options.height === -1 ? 'Pre' : 'Post';
+  ['left', 'top', 'width', 'height'].forEach(function (name) {
+    const value = options[name];
+    if (is.integer(value) && value >= 0) {
+      this.options[name + (name === 'left' || name === 'top' ? 'Offset' : '') + suffix] = value;
+    } else {
+      throw new Error('Non-integer value for ' + name + ' of ' + value);
+    }
+  }, this);
+  // Ensure existing rotation occurs before pre-resize extraction
+  if (suffix === 'Pre' && ((this.options.angle % 360) !== 0 || this.options.useExifOrientation === true)) {
+    this.options.rotateBeforePreExtract = true;
+  }
+  return this;
+}
+
+/**
+ * Trim "boring" pixels from all edges that contain values similar to the top-left pixel.
+ * The `info` response Object will contain `trimOffsetLeft` and `trimOffsetTop` properties.
+ * @param {Number} [threshold=10] the allowed difference from the top-left pixel, a number greater than zero.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function trim (threshold) {
+  if (!is.defined(threshold)) {
+    this.options.trimThreshold = 10;
+  } else if (is.number(threshold) && threshold > 0) {
+    this.options.trimThreshold = threshold;
+  } else {
+    throw is.invalidParameterError('threshold', 'number greater than zero', threshold);
+  }
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with resize-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Object.assign(Sharp.prototype, {
+    resize,
+    extend,
+    extract,
+    trim
+  });
+  // Class attributes
+  Sharp.gravity = gravity;
+  Sharp.strategy = strategy;
+  Sharp.kernel = kernel;
+  Sharp.fit = fit;
+  Sharp.position = position;
+};

lib/utility.js

@@ -0,0 +1,113 @@
+'use strict';
+
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Gets or, when options are provided, sets the limits of _libvips'_ operation cache.
+ * Existing entries in the cache will be trimmed after any change in limits.
+ * This method always returns cache statistics,
+ * useful for determining how much working memory is required for a particular task.
+ *
+ * @example
+ * const stats = sharp.cache();
+ * @example
+ * sharp.cache( { items: 200 } );
+ * sharp.cache( { files: 0 } );
+ * sharp.cache(false);
+ *
+ * @param {Object|Boolean} [options=true] - Object with the following attributes, or Boolean where true uses default cache settings and false removes all caching
+ * @param {Number} [options.memory=50] - is the maximum memory in MB to use for this cache
+ * @param {Number} [options.files=20] - is the maximum number of files to hold open
+ * @param {Number} [options.items=100] - is the maximum number of operations to cache
+ * @returns {Object}
+ */
+function cache (options) {
+  if (is.bool(options)) {
+    if (options) {
+      // Default cache settings of 50MB, 20 files, 100 items
+      return sharp.cache(50, 20, 100);
+    } else {
+      return sharp.cache(0, 0, 0);
+    }
+  } else if (is.object(options)) {
+    return sharp.cache(options.memory, options.files, options.items);
+  } else {
+    return sharp.cache();
+  }
+}
+cache(true);
+
+/**
+ * Gets or, when a concurrency is provided, sets
+ * the number of threads _libvips'_ should create to process each image.
+ * The default value is the number of CPU cores.
+ * A value of `0` will reset to this default.
+ *
+ * The maximum number of images that can be processed in parallel
+ * is limited by libuv's `UV_THREADPOOL_SIZE` environment variable.
+ *
+ * This method always returns the current concurrency.
+ *
+ * @example
+ * const threads = sharp.concurrency(); // 4
+ * sharp.concurrency(2); // 2
+ * sharp.concurrency(0); // 4
+ *
+ * @param {Number} [concurrency]
+ * @returns {Number} concurrency
+ */
+function concurrency (concurrency) {
+  return sharp.concurrency(is.integer(concurrency) ? concurrency : null);
+}
+
+/**
+ * Provides access to internal task counters.
+ * - queue is the number of tasks this module has queued waiting for _libuv_ to provide a worker thread from its pool.
+ * - process is the number of resize tasks currently being processed.
+ *
+ * @example
+ * const counters = sharp.counters(); // { queue: 2, process: 4 }
+ *
+ * @returns {Object}
+ */
+function counters () {
+  return sharp.counters();
+}
+
+/**
+ * Get and set use of SIMD vector unit instructions.
+ * Requires libvips to have been compiled with liborc support.
+ *
+ * Improves the performance of `resize`, `blur` and `sharpen` operations
+ * by taking advantage of the SIMD vector unit of the CPU, e.g. Intel SSE and ARM NEON.
+ *
+ * @example
+ * const simd = sharp.simd();
+ * // simd is `true` if the runtime use of liborc is currently enabled
+ * @example
+ * const simd = sharp.simd(false);
+ * // prevent libvips from using liborc at runtime
+ *
+ * @param {Boolean} [simd=true]
+ * @returns {Boolean}
+ */
+function simd (simd) {
+  return sharp.simd(is.bool(simd) ? simd : null);
+}
+simd(true);
+
+/**
+ * Decorate the Sharp class with utility-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    cache,
+    concurrency,
+    counters,
+    simd
+  ].forEach(function (f) {
+    Sharp[f.name] = f;
+  });
+};

mkdocs.yml

@@ -0,0 +1,27 @@
+site_name: sharp
+site_url: https://sharp.pixelplumbing.com/
+repo_url: https://github.com/lovell/sharp
+site_description: High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP and TIFF images
+copyright: <a href="https://pixelplumbing.com/">pixelplumbing.com</a>
+google_analytics: ['UA-13034748-12', 'sharp.pixelplumbing.com']
+theme: readthedocs
+extra_css:
+  - css/extra.css
+markdown_extensions:
+  - toc:
+      permalink: True
+pages:
+  - Home: index.md
+  - Installation: install.md
+  - API:
+    - Constructor: api-constructor.md
+    - Input: api-input.md
+    - Output: api-output.md
+    - "Resizing images": api-resize.md
+    - "Compositing images": api-composite.md
+    - "Image operations": api-operation.md
+    - "Colour manipulation": api-colour.md
+    - "Channel manipulation": api-channel.md
+    - Utilities: api-utility.md
+  - Performance: performance.md
+  - Changelog: changelog.md

package.json

@@ -1,7 +1,9 @@
 {
   "name": "sharp",
-  "version": "0.8.0",
+  "description": "High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP and TIFF images",
+  "version": "0.22.0",
   "author": "Lovell Fuller <npm@lovell.info>",
+  "homepage": "https://github.com/lovell/sharp",
   "contributors": [
     "Pierre Inglebert <pierre.inglebert@gmail.com>",
     "Jonathan Ong <jonathanrichardong@gmail.com>",
@@ -11,13 +13,65 @@
     "Julian Walker <julian@fiftythree.com>",
     "Amit Pitaru <pitaru.amit@gmail.com>",
     "Brandon Aaron <hello.brandon@aaron.sh>",
-    "Andreas Lind <andreas@one.com>"
+    "Andreas Lind <andreas@one.com>",
+    "Maurus Cuelenaere <mcuelenaere@gmail.com>",
+    "Linus Unnebäck <linus@folkdatorn.se>",
+    "Victor Mateevitsi <mvictoras@gmail.com>",
+    "Alaric Holloway <alaric.holloway@gmail.com>",
+    "Bernhard K. Weisshuhn <bkw@codingforce.com>",
+    "Chris Riley <criley@primedia.com>",
+    "David Carley <dacarley@gmail.com>",
+    "John Tobin <john@limelightmobileinc.com>",
+    "Kenton Gray <kentongray@gmail.com>",
+    "Felix Bünemann <Felix.Buenemann@gmail.com>",
+    "Samy Al Zahrani <samyalzahrany@gmail.com>",
+    "Chintan Thakkar <lemnisk8@gmail.com>",
+    "F. Orlando Galashan <frulo@gmx.de>",
+    "Kleis Auke Wolthuizen <info@kleisauke.nl>",
+    "Matt Hirsch <mhirsch@media.mit.edu>",
+    "Matthias Thoemmes <thoemmes@gmail.com>",
+    "Patrick Paskaris <patrick@paskaris.gr>",
+    "Jérémy Lal <kapouer@melix.org>",
+    "Rahul Nanwani <r.nanwani@gmail.com>",
+    "Alice Monday <alice0meta@gmail.com>",
+    "Kristo Jorgenson <kristo.jorgenson@gmail.com>",
+    "YvesBos <yves_bos@outlook.com>",
+    "Guy Maliar <guy@tailorbrands.com>",
+    "Nicolas Coden <nicolas@ncoden.fr>",
+    "Matt Parrish <matt.r.parrish@gmail.com>",
+    "Marcel Bretschneider <marcel.bretschneider@gmail.com>",
+    "Matthew McEachen <matthew+github@mceachen.org>",
+    "Jarda Kotěšovec <jarda.kotesovec@gmail.com>",
+    "Kenric D'Souza <kenric.dsouza@gmail.com>",
+    "Oleh Aleinyk <oleg.aleynik@gmail.com>",
+    "Marcel Bretschneider <marcel.bretschneider@gmail.com>",
+    "Andrea Bianco <andrea.bianco@unibas.ch>",
+    "Rik Heywood <rik@rik.org>",
+    "Thomas Parisot <hi@oncletom.io>",
+    "Nathan Graves <nathanrgraves+github@gmail.com>",
+    "Tom Lokhorst <tom@lokhorst.eu>",
+    "Espen Hovlandsdal <espen@hovlandsdal.com>",
+    "Sylvain Dumont <sylvain.dumont35@gmail.com>",
+    "Alun Davies <alun.owain.davies@googlemail.com>",
+    "Aidan Hoolachan <ajhoolachan21@gmail.com>",
+    "Axel Eirola <axel.eirola@iki.fi>",
+    "Freezy <freezy@xbmc.org>",
+    "Daiz <taneli.vatanen@gmail.com>",
+    "Julian Aubourg <j@ubourg.net>",
+    "Keith Belovay <keith@picthrive.com>",
+    "Michael B. Klein <mbklein@gmail.com>"
   ],
-  "description": "High performance Node.js module to resize JPEG, PNG, WebP and TIFF images using the libvips library",
   "scripts": {
-    "test": "node ./node_modules/istanbul/lib/cli.js cover ./node_modules/mocha/bin/_mocha -- --slow=5000 --timeout=10000 ./test/unit/*.js"
+    "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node-gyp rebuild && node install/dll-copy)",
+    "clean": "rm -rf node_modules/ build/ vendor/ .nyc_output/ coverage/ test/fixtures/output.*",
+    "test": "semistandard && cc && npm run test-unit && npm run test-licensing && prebuild-ci",
+    "test-unit": "nyc --reporter=lcov --branches=99 mocha --slow=5000 --timeout=60000 ./test/unit/*.js",
+    "test-licensing": "license-checker --production --summary --onlyAllow=\"Apache-2.0;BSD;ISC;MIT\"",
+    "test-coverage": "./test/coverage/report.sh",
+    "test-leak": "./test/leak/leak.sh",
+    "docs": "for m in constructor input resize composite operation colour channel output utility; do documentation build --shallow --format=md --markdown-toc=false lib/$m.js >docs/api-$m.md; done"
   },
-  "main": "index.js",
+  "main": "lib/index.js",
   "repository": {
     "type": "git",
     "url": "git://github.com/lovell/sharp"
@@ -28,30 +82,64 @@
     "webp",
     "tiff",
     "gif",
+    "svg",
+    "dzi",
+    "image",
     "resize",
     "thumbnail",
-    "sharpen",
     "crop",
-    "extract",
     "embed",
     "libvips",
-    "vips",
-    "stream"
+    "vips"
   ],
   "dependencies": {
-    "bluebird": "^2.3.11",
-    "color": "^0.7.1",
-    "nan": "^1.4.1",
-    "semver": "^4.1.0"
+    "bindings": "^1.5.0",
+    "color": "^3.1.0",
+    "detect-libc": "^1.0.3",
+    "fs-copy-file-sync": "^1.1.1",
+    "nan": "^2.13.1",
+    "npmlog": "^4.1.2",
+    "prebuild-install": "^5.2.5",
+    "semver": "^5.6.0",
+    "simple-get": "^3.0.3",
+    "tar": "^4.4.8",
+    "tunnel-agent": "^0.6.0"
   },
   "devDependencies": {
-    "mocha": "^2.0.1",
-    "mocha-jshint": "^0.0.9",
-    "istanbul": "^0.3.2",
-    "coveralls": "^2.11.2"
+    "async": "^2.6.2",
+    "cc": "^1.0.2",
+    "decompress-zip": "^0.3.2",
+    "documentation": "^9.3.1",
+    "exif-reader": "^1.0.2",
+    "icc": "^1.0.0",
+    "license-checker": "^25.0.1",
+    "mocha": "^6.0.2",
+    "mock-fs": "^4.8.0",
+    "nyc": "^13.3.0",
+    "prebuild": "8.1.0",
+    "prebuild-ci": "^2.3.0",
+    "rimraf": "^2.6.3",
+    "semistandard": "^13.0.1"
+  },
+  "license": "Apache-2.0",
+  "config": {
+    "libvips": "8.7.4"
   },
-  "license": "Apache 2.0",
   "engines": {
-    "node": ">=0.10"
+    "node": ">=6"
+  },
+  "semistandard": {
+    "env": [
+      "mocha"
+    ]
+  },
+  "cc": {
+    "linelength": "120",
+    "filter": [
+      "build/c++11",
+      "build/include",
+      "runtime/indentation_namespace",
+      "runtime/references"
+    ]
   }
 }

preinstall.sh

@@ -1,151 +0,0 @@
-#!/bin/sh
-
-# Ensures libvips is installed and attempts to install it if not
-# Currently supports:
-# * Mac OS
-# * Debian Linux
-#   * Debian 7, 8
-#   * Ubuntu 12.04, 14.04, 14.10, 15.04
-#   * Mint 13, 17
-# * Red Hat Linux
-#   * RHEL/Centos/Scientific 6, 7
-#   * Fedora 21, 22
-
-vips_version_minimum=7.40.0
-vips_version_latest_major=7.40
-vips_version_latest_minor=11
-
-install_libvips_from_source() {
-  echo "Compiling libvips $vips_version_latest_major.$vips_version_latest_minor from source"
-  curl -O http://www.vips.ecs.soton.ac.uk/supported/$vips_version_latest_major/vips-$vips_version_latest_major.$vips_version_latest_minor.tar.gz
-  tar zvxf vips-$vips_version_latest_major.$vips_version_latest_minor.tar.gz
-  cd vips-$vips_version_latest_major.$vips_version_latest_minor
-  ./configure --enable-debug=no --enable-docs=no --enable-cxx=yes --without-python --without-orc --without-fftw $1
-  make
-  make install
-  cd ..
-  rm -rf vips-$vips_version_latest_major.$vips_version_latest_minor
-  rm vips-$vips_version_latest_major.$vips_version_latest_minor.tar.gz
-  ldconfig
-  echo "Installed libvips $vips_version_latest_major.$vips_version_latest_minor"
-}
-
-sorry() {
-  echo "Sorry, I don't yet know how to install libvips on $1"
-  exit 1
-}
-
-# Is libvips already installed, and is it at least the minimum required version?
-
-if ! type pkg-config >/dev/null; then
-  sorry "a system without pkg-config"
-fi
-
-pkg_config_path_homebrew=`which brew >/dev/null 2>&1 && eval $(brew --env) && echo $PKG_CONFIG_LIBDIR || true`
-pkg_config_path="$pkg_config_path_homebrew:$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig:/usr/lib/pkgconfig"
-
-PKG_CONFIG_PATH=$pkg_config_path pkg-config --exists vips
-if [ $? -eq 0 ]; then
-  vips_version_found=$(PKG_CONFIG_PATH=$pkg_config_path pkg-config --modversion vips)
-  pkg-config --atleast-version=$vips_version_minimum vips
-  if [ $? -eq 0 ]; then
-    # Found suitable version of libvips
-    echo "Found libvips $vips_version_found"
-    exit 0
-  fi
-  echo "Found libvips $vips_version_found but require $vips_version_minimum"
-else
-  echo "Could not find libvips using a PKG_CONFIG_PATH of '$pkg_config_path'"
-fi
-
-# Verify root/sudo access
-if [ "$(id -u)" -ne "0" ]; then
-  echo "Sorry, I need root/sudo access to continue"
-  exit 1
-fi
-
-# OS-specific installations of libvips follows
-
-case $(uname -s) in
-  *[Dd]arwin*)
-    # Mac OS
-    echo "Detected Mac OS"
-    if type "brew" > /dev/null; then
-      echo "Installing libvips via homebrew"
-      brew install homebrew/science/vips --with-webp --with-graphicsmagick
-    elif type "port" > /dev/null; then
-      echo "Installing libvips via MacPorts"
-      port install vips
-    else
-      sorry "Mac OS without homebrew or MacPorts"
-    fi
-    ;;
-  *)
-    if [ -f /etc/debian_version ]; then
-      # Debian Linux
-      DISTRO=$(lsb_release -c -s)
-      echo "Detected Debian Linux '$DISTRO'"
-      case "$DISTRO" in
-        jessie|vivid)
-          # Debian 8, Ubuntu 15
-          echo "Installing libvips via apt-get"
-          apt-get install -y libvips-dev
-          ;;
-        trusty|utopic|qiana|rebecca)
-          # Ubuntu 14, Mint 17
-          echo "Installing libvips dependencies via apt-get"
-          apt-get install -y automake build-essential gobject-introspection gtk-doc-tools libglib2.0-dev libjpeg-turbo8-dev libpng12-dev libwebp-dev libtiff5-dev libexif-dev libxml2-dev swig libmagickwand-dev curl
-          install_libvips_from_source
-          ;;
-        precise|wheezy|maya)
-          # Debian 7, Ubuntu 12.04, Mint 13
-          echo "Installing libvips dependencies via apt-get"
-          add-apt-repository -y ppa:lyrasis/precise-backports
-          apt-get update
-          apt-get install -y automake build-essential gobject-introspection gtk-doc-tools libglib2.0-dev libjpeg-turbo8-dev libpng12-dev libwebp-dev libtiff4-dev libexif-dev libxml2-dev swig libmagickwand-dev curl
-          install_libvips_from_source
-          ;;
-        *)
-          # Unsupported Debian-based OS
-          sorry "Debian-based $DISTRO"
-          ;;
-      esac
-    elif [ -f /etc/redhat-release ]; then
-      # Red Hat Linux
-      RELEASE=$(cat /etc/redhat-release)
-      echo "Detected Red Hat Linux '$RELEASE'"
-      case $RELEASE in
-        "Red Hat Enterprise Linux release 7."*|"CentOS Linux release 7."*|"Scientific Linux release 7."*)
-          # RHEL/CentOS 7
-          echo "Installing libvips dependencies via yum"
-          yum groupinstall -y "Development Tools"
-          yum install -y gtk-doc libxml2-devel libjpeg-turbo-devel libpng-devel libtiff-devel libexif-devel ImageMagick-devel gobject-introspection-devel libwebp-devel curl
-          install_libvips_from_source "--prefix=/usr"
-          ;;
-        "Red Hat Enterprise Linux release 6."*|"CentOS release 6."*|"Scientific Linux release 6."*)
-          # RHEL/CentOS 6
-          echo "Installing libvips dependencies via yum"
-          yum groupinstall -y "Development Tools"
-          yum install -y gtk-doc libxml2-devel libjpeg-turbo-devel libpng-devel libtiff-devel libexif-devel ImageMagick-devel curl
-          yum install -y http://li.nux.ro/download/nux/dextop/el6/x86_64/nux-dextop-release-0-2.el6.nux.noarch.rpm
-          yum install -y --enablerepo=nux-dextop gobject-introspection-devel
-          yum install -y http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
-          yum install -y --enablerepo=remi libwebp-devel
-          install_libvips_from_source "--prefix=/usr"
-          ;;
-        "Fedora release 21 "*|"Fedora release 22 "*)
-          # Fedora 21, 22
-          echo "Installing libvips via yum"
-          yum install vips-devel
-          ;;
-        *)
-          # Unsupported RHEL-based OS
-          sorry "$RELEASE"
-          ;;
-      esac
-    else
-      # Unsupported OS
-      sorry "$(uname -a)"
-    fi
-    ;;
-esac

src/common.cc

@@ -1,11 +1,93 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cstdlib>
 #include <string>
 #include <string.h>
-#include <vips/vips.h>
+#include <vector>
+#include <queue>
+#include <mutex>
+
+#include <node.h>
+#include <node_buffer.h>
+#include <nan.h>
+#include <vips/vips8>
 
 #include "common.h"
 
+using vips::VImage;
+
 namespace sharp {
 
+  // Convenience methods to access the attributes of a v8::Object
+  bool HasAttr(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::Has(obj, Nan::New(attr).ToLocalChecked()).FromJust();
+  }
+  std::string AttrAsStr(v8::Handle<v8::Object> obj, std::string attr) {
+    return *Nan::Utf8String(Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked());
+  }
+  std::vector<double> AttrAsRgba(v8::Handle<v8::Object> obj, std::string attr) {
+    v8::Local<v8::Object> background = AttrAs<v8::Object>(obj, attr);
+    std::vector<double> rgba(4);
+    for (unsigned int i = 0; i < 4; i++) {
+      rgba[i] = AttrTo<double>(background, i);
+    }
+    return rgba;
+  }
+
+  // Create an InputDescriptor instance from a v8::Object describing an input image
+  InputDescriptor* CreateInputDescriptor(
+    v8::Handle<v8::Object> input, std::vector<v8::Local<v8::Object>> &buffersToPersist
+  ) {
+    Nan::HandleScope();
+    InputDescriptor *descriptor = new InputDescriptor;
+    if (HasAttr(input, "file")) {
+      descriptor->file = AttrAsStr(input, "file");
+    } else if (HasAttr(input, "buffer")) {
+      v8::Local<v8::Object> buffer = AttrAs<v8::Object>(input, "buffer");
+      descriptor->bufferLength = node::Buffer::Length(buffer);
+      descriptor->buffer = node::Buffer::Data(buffer);
+      buffersToPersist.push_back(buffer);
+    }
+    descriptor->failOnError = AttrTo<bool>(input, "failOnError");
+    // Density for vector-based input
+    if (HasAttr(input, "density")) {
+      descriptor->density = AttrTo<double>(input, "density");
+    }
+    // Raw pixel input
+    if (HasAttr(input, "rawChannels")) {
+      descriptor->rawChannels = AttrTo<uint32_t>(input, "rawChannels");
+      descriptor->rawWidth = AttrTo<uint32_t>(input, "rawWidth");
+      descriptor->rawHeight = AttrTo<uint32_t>(input, "rawHeight");
+    }
+    // Multi-page input (GIF, TIFF, PDF)
+    if (HasAttr(input, "pages")) {
+      descriptor->pages = AttrTo<int32_t>(input, "pages");
+    }
+    if (HasAttr(input, "page")) {
+      descriptor->page = AttrTo<uint32_t>(input, "page");
+    }
+    // Create new image
+    if (HasAttr(input, "createChannels")) {
+      descriptor->createChannels = AttrTo<uint32_t>(input, "createChannels");
+      descriptor->createWidth = AttrTo<uint32_t>(input, "createWidth");
+      descriptor->createHeight = AttrTo<uint32_t>(input, "createHeight");
+      descriptor->createBackground = AttrAsRgba(input, "createBackground");
+    }
+    return descriptor;
+  }
+
   // How many tasks are in the queue?
   volatile int counterQueue = 0;
 
@@ -28,19 +110,39 @@ namespace sharp {
   bool IsTiff(std::string const &str) {
     return EndsWith(str, ".tif") || EndsWith(str, ".tiff") || EndsWith(str, ".TIF") || EndsWith(str, ".TIFF");
   }
+  bool IsDz(std::string const &str) {
+    return EndsWith(str, ".dzi") || EndsWith(str, ".DZI");
+  }
+  bool IsDzZip(std::string const &str) {
+    return EndsWith(str, ".zip") || EndsWith(str, ".ZIP") || EndsWith(str, ".szi") || EndsWith(str, ".SZI");
+  }
+  bool IsV(std::string const &str) {
+    return EndsWith(str, ".v") || EndsWith(str, ".V") || EndsWith(str, ".vips") || EndsWith(str, ".VIPS");
+  }
 
-  // Buffer content checkers
-  unsigned char const MARKER_JPEG[] = {0xff, 0xd8};
-  unsigned char const MARKER_PNG[] = {0x89, 0x50};
-  unsigned char const MARKER_WEBP[] = {0x52, 0x49};
-
-  static bool buffer_is_tiff(char *buffer, size_t len) {
-    return (
-      len >= 4 && (
-        (buffer[0] == 'M' && buffer[1] == 'M' && buffer[2] == '\0' && (buffer[3] == '*' || buffer[3] == '+')) ||
-        (buffer[0] == 'I' && buffer[1] == 'I' && (buffer[2] == '*' || buffer[2] == '+') && buffer[3] == '\0')
-      )
-    );
+  /*
+    Provide a string identifier for the given image type.
+  */
+  std::string ImageTypeId(ImageType const imageType) {
+    std::string id;
+    switch (imageType) {
+      case ImageType::JPEG: id = "jpeg"; break;
+      case ImageType::PNG: id = "png"; break;
+      case ImageType::WEBP: id = "webp"; break;
+      case ImageType::TIFF: id = "tiff"; break;
+      case ImageType::GIF: id = "gif"; break;
+      case ImageType::SVG: id = "svg"; break;
+      case ImageType::PDF: id = "pdf"; break;
+      case ImageType::MAGICK: id = "magick"; break;
+      case ImageType::OPENSLIDE: id = "openslide"; break;
+      case ImageType::PPM: id = "ppm"; break;
+      case ImageType::FITS: id = "fits"; break;
+      case ImageType::VIPS: id = "v"; break;
+      case ImageType::RAW: id = "raw"; break;
+      case ImageType::UNKNOWN: id = "unknown"; break;
+      case ImageType::MISSING: id = "missing"; break;
+    }
+    return id;
   }
 
   /*
@@ -48,111 +150,520 @@ namespace sharp {
   */
   ImageType DetermineImageType(void *buffer, size_t const length) {
     ImageType imageType = ImageType::UNKNOWN;
-    if (length >= 4) {
-      if (memcmp(MARKER_JPEG, buffer, 2) == 0) {
+    char const *load = vips_foreign_find_load_buffer(buffer, length);
+    if (load != NULL) {
+      std::string const loader = load;
+      if (EndsWith(loader, "JpegBuffer")) {
         imageType = ImageType::JPEG;
-      } else if (memcmp(MARKER_PNG, buffer, 2) == 0) {
+      } else if (EndsWith(loader, "PngBuffer")) {
         imageType = ImageType::PNG;
-      } else if (memcmp(MARKER_WEBP, buffer, 2) == 0) {
+      } else if (EndsWith(loader, "WebpBuffer")) {
         imageType = ImageType::WEBP;
-      } else if (buffer_is_tiff(static_cast<char*>(buffer), length)) {
+      } else if (EndsWith(loader, "TiffBuffer")) {
         imageType = ImageType::TIFF;
+      } else if (EndsWith(loader, "GifBuffer")) {
+        imageType = ImageType::GIF;
+      } else if (EndsWith(loader, "SvgBuffer")) {
+        imageType = ImageType::SVG;
+      } else if (EndsWith(loader, "PdfBuffer")) {
+        imageType = ImageType::PDF;
+      } else if (EndsWith(loader, "MagickBuffer")) {
+        imageType = ImageType::MAGICK;
       }
     }
     return imageType;
   }
 
   /*
-    Initialise and return a VipsImage from a buffer. Supports JPEG, PNG, WebP and TIFF.
-  */
-  VipsImage* InitImage(ImageType imageType, void *buffer, size_t const length, VipsAccess const access) {
-    VipsImage *image = NULL;
-    if (imageType == ImageType::JPEG) {
-      vips_jpegload_buffer(buffer, length, &image, "access", access, NULL);
-    } else if (imageType == ImageType::PNG) {
-      vips_pngload_buffer(buffer, length, &image, "access", access, NULL);
-    } else if (imageType == ImageType::WEBP) {
-      vips_webpload_buffer(buffer, length, &image, "access", access, NULL);
-    } else if (imageType == ImageType::TIFF) {
-      vips_tiffload_buffer(buffer, length, &image, "access", access, NULL);
-    }
-    return image;
-  }
-
-  /*
-    Inpect the first 2-4 bytes of a file to determine image format
+    Determine image format, reads the first few bytes of the file
   */
   ImageType DetermineImageType(char const *file) {
     ImageType imageType = ImageType::UNKNOWN;
-    if (vips_foreign_is_a("jpegload", file)) {
-      imageType = ImageType::JPEG;
-    } else if (vips_foreign_is_a("pngload", file)) {
-      imageType = ImageType::PNG;
-    } else if (vips_foreign_is_a("webpload", file)) {
-      imageType = ImageType::WEBP;
-    } else if (vips_foreign_is_a("tiffload", file)) {
-      imageType = ImageType::TIFF;
-    } else if(vips_foreign_is_a("magickload", file)) {
-      imageType = ImageType::MAGICK;
+    char const *load = vips_foreign_find_load(file);
+    if (load != nullptr) {
+      std::string const loader = load;
+      if (EndsWith(loader, "JpegFile")) {
+        imageType = ImageType::JPEG;
+      } else if (EndsWith(loader, "Png")) {
+        imageType = ImageType::PNG;
+      } else if (EndsWith(loader, "WebpFile")) {
+        imageType = ImageType::WEBP;
+      } else if (EndsWith(loader, "Openslide")) {
+        imageType = ImageType::OPENSLIDE;
+      } else if (EndsWith(loader, "TiffFile")) {
+        imageType = ImageType::TIFF;
+      } else if (EndsWith(loader, "GifFile")) {
+        imageType = ImageType::GIF;
+      } else if (EndsWith(loader, "SvgFile")) {
+        imageType = ImageType::SVG;
+      } else if (EndsWith(loader, "PdfFile")) {
+        imageType = ImageType::PDF;
+      } else if (EndsWith(loader, "Ppm")) {
+        imageType = ImageType::PPM;
+      } else if (EndsWith(loader, "Fits")) {
+        imageType = ImageType::FITS;
+      } else if (EndsWith(loader, "Vips")) {
+        imageType = ImageType::VIPS;
+      } else if (EndsWith(loader, "Magick") || EndsWith(loader, "MagickFile")) {
+        imageType = ImageType::MAGICK;
+      }
+    } else {
+      if (EndsWith(vips::VError().what(), " not found\n")) {
+        imageType = ImageType::MISSING;
+      }
     }
     return imageType;
   }
 
   /*
-    Initialise and return a VipsImage from a file.
+    Does this image type support multiple pages?
   */
-  VipsImage* InitImage(ImageType imageType, char const *file, VipsAccess const access) {
-    VipsImage *image = NULL;
-    if (imageType == ImageType::JPEG) {
-      vips_jpegload(file, &image, "access", access, NULL);
-    } else if (imageType == ImageType::PNG) {
-      vips_pngload(file, &image, "access", access, NULL);
-    } else if (imageType == ImageType::WEBP) {
-      vips_webpload(file, &image, "access", access, NULL);
-    } else if (imageType == ImageType::TIFF) {
-      vips_tiffload(file, &image, "access", access, NULL);
-    } else if (imageType == ImageType::MAGICK) {
-      vips_magickload(file, &image, "access", access, NULL);
+  bool ImageTypeSupportsPage(ImageType imageType) {
+    return
+      imageType == ImageType::GIF ||
+      imageType == ImageType::TIFF ||
+      imageType == ImageType::PDF;
+  }
+
+  /*
+    Open an image from the given InputDescriptor (filesystem, compressed buffer, raw pixel data)
+  */
+  std::tuple<VImage, ImageType> OpenInput(InputDescriptor *descriptor, VipsAccess accessMethod) {
+    VImage image;
+    ImageType imageType;
+    if (descriptor->buffer != nullptr) {
+      if (descriptor->rawChannels > 0) {
+        // Raw, uncompressed pixel data
+        image = VImage::new_from_memory(descriptor->buffer, descriptor->bufferLength,
+          descriptor->rawWidth, descriptor->rawHeight, descriptor->rawChannels, VIPS_FORMAT_UCHAR);
+        if (descriptor->rawChannels < 3) {
+          image.get_image()->Type = VIPS_INTERPRETATION_B_W;
+        } else {
+          image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
+        }
+        imageType = ImageType::RAW;
+      } else {
+        // Compressed data
+        imageType = DetermineImageType(descriptor->buffer, descriptor->bufferLength);
+        if (imageType != ImageType::UNKNOWN) {
+          try {
+            vips::VOption *option = VImage::option()
+              ->set("access", accessMethod)
+              ->set("fail", descriptor->failOnError);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+              option->set("dpi", descriptor->density);
+            }
+            if (imageType == ImageType::MAGICK) {
+              option->set("density", std::to_string(descriptor->density).data());
+            }
+            if (ImageTypeSupportsPage(imageType)) {
+              option->set("n", descriptor->pages);
+              option->set("page", descriptor->page);
+            }
+            image = VImage::new_from_buffer(descriptor->buffer, descriptor->bufferLength, nullptr, option);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
+              SetDensity(image, descriptor->density);
+            }
+          } catch (vips::VError const &err) {
+            throw vips::VError(std::string("Input buffer has corrupt header: ") + err.what());
+          }
+        } else {
+          throw vips::VError("Input buffer contains unsupported image format");
+        }
+      }
+    } else {
+      if (descriptor->createChannels > 0) {
+        // Create new image
+        std::vector<double> background = {
+          descriptor->createBackground[0],
+          descriptor->createBackground[1],
+          descriptor->createBackground[2]
+        };
+        if (descriptor->createChannels == 4) {
+          background.push_back(descriptor->createBackground[3]);
+        }
+        image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight).new_from_image(background);
+        image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
+        imageType = ImageType::RAW;
+      } else {
+        // From filesystem
+        imageType = DetermineImageType(descriptor->file.data());
+        if (imageType == ImageType::MISSING) {
+          throw vips::VError("Input file is missing");
+        }
+        if (imageType != ImageType::UNKNOWN) {
+          try {
+            vips::VOption *option = VImage::option()
+              ->set("access", accessMethod)
+              ->set("fail", descriptor->failOnError);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+              option->set("dpi", descriptor->density);
+            }
+            if (imageType == ImageType::MAGICK) {
+              option->set("density", std::to_string(descriptor->density).data());
+            }
+            if (ImageTypeSupportsPage(imageType)) {
+              option->set("n", descriptor->pages);
+              option->set("page", descriptor->page);
+            }
+            image = VImage::new_from_file(descriptor->file.data(), option);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
+              SetDensity(image, descriptor->density);
+            }
+          } catch (vips::VError const &err) {
+            throw vips::VError(std::string("Input file has corrupt header: ") + err.what());
+          }
+        } else {
+          throw vips::VError("Input file contains unsupported image format");
+        }
+      }
     }
-    return image;
+    return std::make_tuple(image, imageType);
+  }
+
+  /*
+    Does this image have an embedded profile?
+  */
+  bool HasProfile(VImage image) {
+    return (image.get_typeof(VIPS_META_ICC_NAME) != 0) ? TRUE : FALSE;
   }
 
   /*
     Does this image have an alpha channel?
     Uses colour space interpretation with number of channels to guess this.
   */
-  bool HasAlpha(VipsImage *image) {
+  bool HasAlpha(VImage image) {
+    int const bands = image.bands();
+    VipsInterpretation const interpretation = image.interpretation();
     return (
-      (image->Bands == 2 && image->Type == VIPS_INTERPRETATION_B_W) ||
-      (image->Bands == 4 && image->Type != VIPS_INTERPRETATION_CMYK) ||
-      (image->Bands == 5 && image->Type == VIPS_INTERPRETATION_CMYK)
-    );
+      (bands == 2 && interpretation == VIPS_INTERPRETATION_B_W) ||
+      (bands == 4 && interpretation != VIPS_INTERPRETATION_CMYK) ||
+      (bands == 5 && interpretation == VIPS_INTERPRETATION_CMYK));
   }
 
   /*
     Get EXIF Orientation of image, if any.
   */
-  int ExifOrientation(VipsImage const *image) {
+  int ExifOrientation(VImage image) {
     int orientation = 0;
-    const char *exif;
-    if (
-      vips_image_get_typeof(image, "exif-ifd0-Orientation") != 0 &&
-      !vips_image_get_string(image, "exif-ifd0-Orientation", &exif)
-    ) {
-      orientation = atoi(&exif[0]);
+    if (image.get_typeof(VIPS_META_ORIENTATION) != 0) {
+      orientation = image.get_int(VIPS_META_ORIENTATION);
     }
     return orientation;
   }
 
   /*
-    Returns the window size for the named interpolator. For example,
-    a window size of 3 means a 3x3 pixel grid is used for the calculation.
+    Set EXIF Orientation of image.
   */
-  int InterpolatorWindowSize(char const *name) {
-    VipsInterpolate *interpolator = vips_interpolate_new(name);
-    int window_size = vips_interpolate_get_window_size(interpolator);
-    g_object_unref(interpolator);
-    return window_size;
+  void SetExifOrientation(VImage image, int const orientation) {
+    image.set(VIPS_META_ORIENTATION, orientation);
   }
 
-} // namespace
+  /*
+    Remove EXIF Orientation from image.
+  */
+  void RemoveExifOrientation(VImage image) {
+    vips_image_remove(image.get_image(), VIPS_META_ORIENTATION);
+  }
+
+  /*
+    Does this image have a non-default density?
+  */
+  bool HasDensity(VImage image) {
+    return image.xres() > 1.0;
+  }
+
+  /*
+    Get pixels/mm resolution as pixels/inch density.
+  */
+  int GetDensity(VImage image) {
+    return static_cast<int>(round(image.xres() * 25.4));
+  }
+
+  /*
+    Set pixels/mm resolution based on a pixels/inch density.
+  */
+  void SetDensity(VImage image, const double density) {
+    const double pixelsPerMm = density / 25.4;
+    image.set("Xres", pixelsPerMm);
+    image.set("Yres", pixelsPerMm);
+    image.set(VIPS_META_RESOLUTION_UNIT, "in");
+  }
+
+  /*
+    Check the proposed format supports the current dimensions.
+  */
+  void AssertImageTypeDimensions(VImage image, ImageType const imageType) {
+    if (imageType == ImageType::JPEG) {
+      if (image.width() > 65535 || image.height() > 65535) {
+        throw vips::VError("Processed image is too large for the JPEG format");
+      }
+    } else if (imageType == ImageType::WEBP) {
+      if (image.width() > 16383 || image.height() > 16383) {
+        throw vips::VError("Processed image is too large for the WebP format");
+      }
+    }
+  }
+
+  /*
+    Called when a Buffer undergoes GC, required to support mixed runtime libraries in Windows
+  */
+  void FreeCallback(char* data, void* hint) {
+    if (data != nullptr) {
+      g_free(data);
+    }
+  }
+
+  /*
+    Temporary buffer of warnings
+  */
+  std::queue<std::string> vipsWarnings;
+  std::mutex vipsWarningsMutex;
+
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore) {
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    vipsWarnings.emplace(message);
+  }
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop() {
+    std::string warning;
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    if (!vipsWarnings.empty()) {
+      warning = vipsWarnings.front();
+      vipsWarnings.pop();
+    }
+    return warning;
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during an embed.
+
+    @Azurebyte: We are basically swapping the inWidth and outWidth, inHeight and outHeight from the CalculateCrop function.
+  */
+  std::tuple<int, int> CalculateEmbedPosition(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity) {
+
+    int left = 0;
+    int top = 0;
+    switch (gravity) {
+      case 1:
+        // North
+        left = (outWidth - inWidth) / 2;
+        break;
+      case 2:
+        // East
+        left = outWidth - inWidth;
+        top = (outHeight - inHeight) / 2;
+        break;
+      case 3:
+        // South
+        left = (outWidth - inWidth) / 2;
+        top = outHeight - inHeight;
+        break;
+      case 4:
+        // West
+        top = (outHeight - inHeight) / 2;
+        break;
+      case 5:
+        // Northeast
+        left = outWidth - inWidth;
+        break;
+      case 6:
+        // Southeast
+        left = outWidth - inWidth;
+        top = outHeight - inHeight;
+        break;
+      case 7:
+        // Southwest
+        top = outHeight - inHeight;
+        break;
+      case 8:
+        // Northwest
+        // Which is the default is 0,0 so we do not assign anything here.
+        break;
+      default:
+        // Centre
+        left = (outWidth - inWidth) / 2;
+        top = (outHeight - inHeight) / 2;
+    }
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during a crop.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity) {
+
+    int left = 0;
+    int top = 0;
+    switch (gravity) {
+      case 1:
+        // North
+        left = (inWidth - outWidth + 1) / 2;
+        break;
+      case 2:
+        // East
+        left = inWidth - outWidth;
+        top = (inHeight - outHeight + 1) / 2;
+        break;
+      case 3:
+        // South
+        left = (inWidth - outWidth + 1) / 2;
+        top = inHeight - outHeight;
+        break;
+      case 4:
+        // West
+        top = (inHeight - outHeight + 1) / 2;
+        break;
+      case 5:
+        // Northeast
+        left = inWidth - outWidth;
+        break;
+      case 6:
+        // Southeast
+        left = inWidth - outWidth;
+        top = inHeight - outHeight;
+        break;
+      case 7:
+        // Southwest
+        top = inHeight - outHeight;
+        break;
+      case 8:
+        // Northwest
+        break;
+      default:
+        // Centre
+        left = (inWidth - outWidth + 1) / 2;
+        top = (inHeight - outHeight + 1) / 2;
+    }
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given x and y offsets.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const x, int const y) {
+
+    // default values
+    int left = 0;
+    int top = 0;
+
+    // assign only if valid
+    if (x >= 0 && x < (inWidth - outWidth)) {
+      left = x;
+    } else if (x >= (inWidth - outWidth)) {
+      left = inWidth - outWidth;
+    }
+
+    if (y >= 0 && y < (inHeight - outHeight)) {
+      top = y;
+    } else if (y >= (inHeight - outHeight)) {
+      top = inHeight - outHeight;
+    }
+
+    // the resulting left and top could have been outside the image after calculation from bottom/right edges
+    if (left < 0) {
+      left = 0;
+    }
+    if (top < 0) {
+      top = 0;
+    }
+
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Are pixel values in this image 16-bit integer?
+  */
+  bool Is16Bit(VipsInterpretation const interpretation) {
+    return interpretation == VIPS_INTERPRETATION_RGB16 || interpretation == VIPS_INTERPRETATION_GREY16;
+  }
+
+  /*
+    Return the image alpha maximum. Useful for combining alpha bands. scRGB
+    images are 0 - 1 for image data, but the alpha is 0 - 255.
+  */
+  double MaximumImageAlpha(VipsInterpretation const interpretation) {
+    return Is16Bit(interpretation) ? 65535.0 : 255.0;
+  }
+
+  /*
+    Get boolean operation type from string
+  */
+  VipsOperationBoolean GetBooleanOperation(std::string const opStr) {
+    return static_cast<VipsOperationBoolean>(
+      vips_enum_from_nick(nullptr, VIPS_TYPE_OPERATION_BOOLEAN, opStr.data()));
+  }
+
+  /*
+    Get interpretation type from string
+  */
+  VipsInterpretation GetInterpretation(std::string const typeStr) {
+    return static_cast<VipsInterpretation>(
+      vips_enum_from_nick(nullptr, VIPS_TYPE_INTERPRETATION, typeStr.data()));
+  }
+
+  /*
+    Convert RGBA value to another colourspace
+  */
+  std::vector<double> GetRgbaAsColourspace(std::vector<double> const rgba, VipsInterpretation const interpretation) {
+    int const bands = static_cast<int>(rgba.size());
+    if (bands < 3 || interpretation == VIPS_INTERPRETATION_sRGB || interpretation == VIPS_INTERPRETATION_RGB) {
+      return rgba;
+    } else {
+      VImage pixel = VImage::new_matrix(1, 1);
+      pixel.set("bands", bands);
+      pixel = pixel.new_from_image(rgba);
+      pixel = pixel.colourspace(interpretation, VImage::option()->set("source_space", VIPS_INTERPRETATION_sRGB));
+      return pixel(0, 0);
+    }
+  }
+
+  /*
+    Apply the alpha channel to a given colour
+  */
+  std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, std::vector<double> colour) {
+    // Scale up 8-bit values to match 16-bit input image
+    double const multiplier = sharp::Is16Bit(image.interpretation()) ? 256.0 : 1.0;
+    // Create alphaColour colour
+    std::vector<double> alphaColour;
+    if (image.bands() > 2) {
+      alphaColour = {
+        multiplier * colour[0],
+        multiplier * colour[1],
+        multiplier * colour[2]
+      };
+    } else {
+      // Convert sRGB to greyscale
+      alphaColour = { multiplier * (
+        0.2126 * colour[0] +
+        0.7152 * colour[1] +
+        0.0722 * colour[2])
+      };
+    }
+    // Add alpha channel to alphaColour colour
+    if (colour[3] < 255.0 || HasAlpha(image)) {
+      alphaColour.push_back(colour[3] * multiplier);
+    }
+    // Ensure alphaColour colour uses correct colourspace
+    alphaColour = sharp::GetRgbaAsColourspace(alphaColour, image.interpretation());
+    // Add non-transparent alpha channel, if required
+    if (colour[3] < 255.0 && !HasAlpha(image)) {
+      image = image.bandjoin(
+        VImage::new_matrix(image.width(), image.height()).new_from_image(255 * multiplier));
+    }
+    return std::make_tuple(image, alphaColour);
+  }
+
+}  // namespace sharp

src/common.h

@@ -1,15 +1,115 @@
-#ifndef SHARP_COMMON_H
-#define SHARP_COMMON_H
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_COMMON_H_
+#define SRC_COMMON_H_
+
+#include <string>
+#include <tuple>
+#include <vector>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+
+// Verify platform and compiler compatibility
+
+#if (VIPS_MAJOR_VERSION < 8 || (VIPS_MAJOR_VERSION == 8 && VIPS_MINOR_VERSION < 7))
+#error libvips version 8.7.0+ is required - see sharp.pixelplumbing.com/page/install
+#endif
+
+#if ((!defined(__clang__)) && defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)))
+#error GCC version 4.6+ is required for C++11 features - see sharp.pixelplumbing.com/page/install#prerequisites
+#endif
+
+#if (defined(__clang__) && defined(__has_feature))
+#if (!__has_feature(cxx_range_for))
+#error clang version 3.0+ is required for C++11 features - see sharp.pixelplumbing.com/page/install#prerequisites
+#endif
+#endif
+
+using vips::VImage;
 
 namespace sharp {
 
+  struct InputDescriptor {
+    std::string name;
+    std::string file;
+    char *buffer;
+    bool failOnError;
+    size_t bufferLength;
+    double density;
+    int rawChannels;
+    int rawWidth;
+    int rawHeight;
+    int pages;
+    int page;
+    int createChannels;
+    int createWidth;
+    int createHeight;
+    std::vector<double> createBackground;
+
+    InputDescriptor():
+      buffer(nullptr),
+      failOnError(TRUE),
+      bufferLength(0),
+      density(72.0),
+      rawChannels(0),
+      rawWidth(0),
+      rawHeight(0),
+      pages(1),
+      page(0),
+      createChannels(0),
+      createWidth(0),
+      createHeight(0),
+      createBackground{ 0.0, 0.0, 0.0, 255.0 } {}
+  };
+
+  // Convenience methods to access the attributes of a v8::Object
+  bool HasAttr(v8::Handle<v8::Object> obj, std::string attr);
+  std::string AttrAsStr(v8::Handle<v8::Object> obj, std::string attr);
+  std::vector<double> AttrAsRgba(v8::Handle<v8::Object> obj, std::string attr);
+  template<typename T> v8::Local<T> AttrAs(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked().As<T>();
+  }
+  template<typename T> T AttrTo(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::To<T>(Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked()).FromJust();
+  }
+  template<typename T> T AttrTo(v8::Handle<v8::Object> obj, int attr) {
+    return Nan::To<T>(Nan::Get(obj, attr).ToLocalChecked()).FromJust();
+  }
+
+  // Create an InputDescriptor instance from a v8::Object describing an input image
+  InputDescriptor* CreateInputDescriptor(
+    v8::Handle<v8::Object> input, std::vector<v8::Local<v8::Object>> &buffersToPersist);
+
   enum class ImageType {
-    UNKNOWN,
     JPEG,
     PNG,
     WEBP,
     TIFF,
-    MAGICK
+    GIF,
+    SVG,
+    PDF,
+    MAGICK,
+    OPENSLIDE,
+    PPM,
+    FITS,
+    VIPS,
+    RAW,
+    UNKNOWN,
+    MISSING
   };
 
   // How many tasks are in the queue?
@@ -23,6 +123,14 @@ namespace sharp {
   bool IsPng(std::string const &str);
   bool IsWebp(std::string const &str);
   bool IsTiff(std::string const &str);
+  bool IsDz(std::string const &str);
+  bool IsDzZip(std::string const &str);
+  bool IsV(std::string const &str);
+
+  /*
+    Provide a string identifier for the given image type.
+  */
+  std::string ImageTypeId(ImageType const imageType);
 
   /*
     Determine image format of a buffer.
@@ -35,32 +143,128 @@ namespace sharp {
   ImageType DetermineImageType(char const *file);
 
   /*
-    Initialise and return a VipsImage from a buffer. Supports JPEG, PNG, WebP and TIFF.
+    Does this image type support multiple pages?
   */
-  VipsImage* InitImage(ImageType imageType, void *buffer, size_t const length, VipsAccess const access);
+  bool ImageTypeSupportsPage(ImageType imageType);
 
   /*
-    Initialise and return a VipsImage from a file.
+    Open an image from the given InputDescriptor (filesystem, compressed buffer, raw pixel data)
   */
-  VipsImage* InitImage(ImageType imageType, char const *file, VipsAccess const access);
+  std::tuple<VImage, ImageType> OpenInput(InputDescriptor *descriptor, VipsAccess accessMethod);
+
+  /*
+    Does this image have an embedded profile?
+  */
+  bool HasProfile(VImage image);
 
   /*
     Does this image have an alpha channel?
     Uses colour space interpretation with number of channels to guess this.
   */
-  bool HasAlpha(VipsImage *image);
+  bool HasAlpha(VImage image);
 
   /*
     Get EXIF Orientation of image, if any.
   */
-  int ExifOrientation(VipsImage const *image);
+  int ExifOrientation(VImage image);
 
   /*
-    Returns the window size for the named interpolator. For example,
-    a window size of 3 means a 3x3 pixel grid is used for the calculation.
+    Set EXIF Orientation of image.
   */
-  int InterpolatorWindowSize(char const *name);
+  void SetExifOrientation(VImage image, int const orientation);
 
-} // namespace
+  /*
+    Remove EXIF Orientation from image.
+  */
+  void RemoveExifOrientation(VImage image);
 
-#endif
+  /*
+    Does this image have a non-default density?
+  */
+  bool HasDensity(VImage image);
+
+  /*
+    Get pixels/mm resolution as pixels/inch density.
+  */
+  int GetDensity(VImage image);
+
+  /*
+    Set pixels/mm resolution based on a pixels/inch density.
+  */
+  void SetDensity(VImage image, const double density);
+
+  /*
+    Check the proposed format supports the current dimensions.
+  */
+  void AssertImageTypeDimensions(VImage image, ImageType const imageType);
+
+  /*
+    Called when a Buffer undergoes GC, required to support mixed runtime libraries in Windows
+  */
+  void FreeCallback(char* data, void* hint);
+
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore);
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop();
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during an embed.
+  */
+  std::tuple<int, int> CalculateEmbedPosition(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity);
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity);
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given x and y offsets of the output image.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const x, int const y);
+
+  /*
+    Are pixel values in this image 16-bit integer?
+  */
+  bool Is16Bit(VipsInterpretation const interpretation);
+
+  /*
+    Return the image alpha maximum. Useful for combining alpha bands. scRGB
+    images are 0 - 1 for image data, but the alpha is 0 - 255.
+  */
+  double MaximumImageAlpha(VipsInterpretation const interpretation);
+
+  /*
+    Get boolean operation type from string
+  */
+  VipsOperationBoolean GetBooleanOperation(std::string const opStr);
+
+  /*
+    Get interpretation type from string
+  */
+  VipsInterpretation GetInterpretation(std::string const typeStr);
+
+  /*
+    Convert RGBA value to another colourspace
+  */
+  std::vector<double> GetRgbaAsColourspace(std::vector<double> const rgba, VipsInterpretation const interpretation);
+
+  /*
+    Apply the alpha channel to a given colour
+   */
+  std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, std::vector<double> colour);
+
+}  // namespace sharp
+
+#endif  // SRC_COMMON_H_

src/libvips/cplusplus/VError.cpp

@@ -0,0 +1,52 @@
+// Code for error type
+
+/*
+
+    Copyright (C) 1991-2001 The National Gallery
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <iostream>
+
+#include <vips/vips8>
+
+VIPS_NAMESPACE_START
+
+std::ostream &operator<<( std::ostream &file, const VError &err )
+{
+	err.ostream_print( file );
+	return( file );
+}
+
+void VError::ostream_print( std::ostream &file ) const
+{
+	file << _what;
+}
+
+VIPS_NAMESPACE_END

src/libvips/cplusplus/VInterpolate.cpp

@@ -0,0 +1,76 @@
+/* Object part of VInterpolate class
+ */
+
+/*
+
+    Copyright (C) 1991-2001 The National Gallery
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <vips/vips8>
+
+#include <vips/debug.h>
+
+/*
+#define VIPS_DEBUG
+#define VIPS_DEBUG_VERBOSE
+ */
+
+VIPS_NAMESPACE_START
+
+VInterpolate 
+VInterpolate::new_from_name( const char *name, VOption *options )
+{
+	VipsInterpolate *interp;
+
+	if( !(interp = vips_interpolate_new( name )) ) {
+		delete options; 
+		throw VError(); 
+	}
+	delete options; 
+
+	VInterpolate out( interp ); 
+
+	return( out ); 
+}
+
+VOption *
+VOption::set( const char *name, VInterpolate value )
+{
+	Pair *pair = new Pair( name );
+
+	pair->input = true;
+	g_value_init( &pair->value, VIPS_TYPE_INTERPOLATE );
+	g_value_set_object( &pair->value, value.get_interpolate() );
+	options.push_back( pair );
+
+	return( this );
+}
+
+VIPS_NAMESPACE_END

src/metadata.cc

@@ -1,145 +1,239 @@
-#include <node.h>
-#include <vips/vips.h>
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
-#include "nan.h"
+#include <numeric>
+#include <vector>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
 
 #include "common.h"
 #include "metadata.h"
 
-using namespace v8;
-using namespace sharp;
-
-struct MetadataBaton {
-  // Input
-  std::string fileIn;
-  void* bufferIn;
-  size_t bufferInLength;
-  // Output
-  std::string format;
-  int width;
-  int height;
-  std::string space;
-  int channels;
-  bool hasAlpha;
-  int orientation;
-  std::string err;
-
-  MetadataBaton():
-    bufferInLength(0),
-    orientation(0) {}
-};
-
-class MetadataWorker : public NanAsyncWorker {
-
+class MetadataWorker : public Nan::AsyncWorker {
  public:
-  MetadataWorker(NanCallback *callback, MetadataBaton *baton) : NanAsyncWorker(callback), baton(baton) {}
+  MetadataWorker(
+    Nan::Callback *callback, MetadataBaton *baton, Nan::Callback *debuglog,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist) :
+    Nan::AsyncWorker(callback, "sharp:MetadataWorker"),
+    baton(baton), debuglog(debuglog),
+    buffersToPersist(buffersToPersist) {
+    // Protect Buffer objects from GC, keyed on index
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        SaveToPersistent(index, buffer);
+        return index + 1;
+      });
+  }
   ~MetadataWorker() {}
 
   void Execute() {
     // Decrement queued task counter
-    g_atomic_int_dec_and_test(&counterQueue);
+    g_atomic_int_dec_and_test(&sharp::counterQueue);
 
-    ImageType imageType = ImageType::UNKNOWN;
-    VipsImage *image = NULL;
-    if (baton->bufferInLength > 1) {
-      // From buffer
-      imageType = DetermineImageType(baton->bufferIn, baton->bufferInLength);
-      if (imageType != ImageType::UNKNOWN) {
-        image = InitImage(imageType, baton->bufferIn, baton->bufferInLength, VIPS_ACCESS_RANDOM);
-      } else {
-        (baton->err).append("Input buffer contains unsupported image format");
-      }
-    } else {
-      // From file
-      imageType = DetermineImageType(baton->fileIn.c_str());
-      if (imageType != ImageType::UNKNOWN) {
-        image = InitImage(imageType, baton->fileIn.c_str(), VIPS_ACCESS_RANDOM);
-      } else {
-        (baton->err).append("File is of an unsupported image format");
-      }
+    vips::VImage image;
+    sharp::ImageType imageType = sharp::ImageType::UNKNOWN;
+    try {
+      std::tie(image, imageType) = OpenInput(baton->input, VIPS_ACCESS_SEQUENTIAL);
+    } catch (vips::VError const &err) {
+      (baton->err).append(err.what());
     }
-    if (image != NULL && imageType != ImageType::UNKNOWN) {
+    if (imageType != sharp::ImageType::UNKNOWN) {
       // Image type
-      switch (imageType) {
-        case ImageType::JPEG: baton->format = "jpeg"; break;
-        case ImageType::PNG: baton->format = "png"; break;
-        case ImageType::WEBP: baton->format = "webp"; break;
-        case ImageType::TIFF: baton->format = "tiff"; break;
-        case ImageType::MAGICK: baton->format = "magick"; break;
-        case ImageType::UNKNOWN: break;
-      }
+      baton->format = sharp::ImageTypeId(imageType);
       // VipsImage attributes
-      baton->width = image->Xsize;
-      baton->height = image->Ysize;
-      baton->space = vips_enum_nick(VIPS_TYPE_INTERPRETATION, image->Type);
-      baton->channels = image->Bands;
+      baton->width = image.width();
+      baton->height = image.height();
+      baton->space = vips_enum_nick(VIPS_TYPE_INTERPRETATION, image.interpretation());
+      baton->channels = image.bands();
+      baton->depth = vips_enum_nick(VIPS_TYPE_BAND_FORMAT, image.format());
+      if (sharp::HasDensity(image)) {
+        baton->density = sharp::GetDensity(image);
+      }
+      if (image.get_typeof("jpeg-chroma-subsample") == VIPS_TYPE_REF_STRING) {
+        baton->chromaSubsampling = image.get_string("jpeg-chroma-subsample");
+      }
+      if (image.get_typeof("interlaced") == G_TYPE_INT) {
+        baton->isProgressive = image.get_int("interlaced") == 1;
+      }
+      if (image.get_typeof("palette-bit-depth") == G_TYPE_INT) {
+        baton->paletteBitDepth = image.get_int("palette-bit-depth");
+      }
+      if (image.get_typeof(VIPS_META_N_PAGES) == G_TYPE_INT) {
+        baton->pages = image.get_int(VIPS_META_N_PAGES);
+      }
+      if (image.get_typeof(VIPS_META_PAGE_HEIGHT) == G_TYPE_INT) {
+        baton->pageHeight = image.get_int(VIPS_META_PAGE_HEIGHT);
+      }
+      baton->hasProfile = sharp::HasProfile(image);
       // Derived attributes
-      baton->hasAlpha = HasAlpha(image);
-      baton->orientation = ExifOrientation(image);
-      // Drop image reference
-      g_object_unref(image);
+      baton->hasAlpha = sharp::HasAlpha(image);
+      baton->orientation = sharp::ExifOrientation(image);
+      // EXIF
+      if (image.get_typeof(VIPS_META_EXIF_NAME) == VIPS_TYPE_BLOB) {
+        size_t exifLength;
+        void const *exif = image.get_blob(VIPS_META_EXIF_NAME, &exifLength);
+        baton->exif = static_cast<char*>(g_malloc(exifLength));
+        memcpy(baton->exif, exif, exifLength);
+        baton->exifLength = exifLength;
+      }
+      // ICC profile
+      if (image.get_typeof(VIPS_META_ICC_NAME) == VIPS_TYPE_BLOB) {
+        size_t iccLength;
+        void const *icc = image.get_blob(VIPS_META_ICC_NAME, &iccLength);
+        baton->icc = static_cast<char*>(g_malloc(iccLength));
+        memcpy(baton->icc, icc, iccLength);
+        baton->iccLength = iccLength;
+      }
+      // IPTC
+      if (image.get_typeof(VIPS_META_IPTC_NAME) == VIPS_TYPE_BLOB) {
+        size_t iptcLength;
+        void const *iptc = image.get_blob(VIPS_META_IPTC_NAME, &iptcLength);
+        baton->iptc = static_cast<char *>(g_malloc(iptcLength));
+        memcpy(baton->iptc, iptc, iptcLength);
+        baton->iptcLength = iptcLength;
+      }
+      // XMP
+      if (image.get_typeof(VIPS_META_XMP_NAME) == VIPS_TYPE_BLOB) {
+        size_t xmpLength;
+        void const *xmp = image.get_blob(VIPS_META_XMP_NAME, &xmpLength);
+        baton->xmp = static_cast<char *>(g_malloc(xmpLength));
+        memcpy(baton->xmp, xmp, xmpLength);
+        baton->xmpLength = xmpLength;
+      }
     }
+
     // Clean up
     vips_error_clear();
     vips_thread_shutdown();
   }
 
-  void HandleOKCallback () {
-    NanScope();
+  void HandleOKCallback() {
+    using Nan::New;
+    using Nan::Set;
+    Nan::HandleScope();
 
-    Handle<Value> argv[2] = { NanNull(), NanNull() };
+    v8::Local<v8::Value> argv[2] = { Nan::Null(), Nan::Null() };
     if (!baton->err.empty()) {
-      // Error
-      argv[0] = Exception::Error(NanNew<String>(baton->err.data(), baton->err.size()));
+      argv[0] = Nan::Error(baton->err.data());
     } else {
       // Metadata Object
-      Local<Object> info = NanNew<Object>();
-      info->Set(NanNew<String>("format"), NanNew<String>(baton->format));
-      info->Set(NanNew<String>("width"), NanNew<Number>(baton->width));
-      info->Set(NanNew<String>("height"), NanNew<Number>(baton->height));
-      info->Set(NanNew<String>("space"), NanNew<String>(baton->space));
-      info->Set(NanNew<String>("channels"), NanNew<Number>(baton->channels));
-      info->Set(NanNew<String>("hasAlpha"), NanNew<Boolean>(baton->hasAlpha));
+      v8::Local<v8::Object> info = New<v8::Object>();
+      Set(info, New("format").ToLocalChecked(), New<v8::String>(baton->format).ToLocalChecked());
+      if (baton->input->bufferLength > 0) {
+        Set(info, New("size").ToLocalChecked(), New<v8::Uint32>(static_cast<uint32_t>(baton->input->bufferLength)));
+      }
+      Set(info, New("width").ToLocalChecked(), New<v8::Uint32>(baton->width));
+      Set(info, New("height").ToLocalChecked(), New<v8::Uint32>(baton->height));
+      Set(info, New("space").ToLocalChecked(), New<v8::String>(baton->space).ToLocalChecked());
+      Set(info, New("channels").ToLocalChecked(), New<v8::Uint32>(baton->channels));
+      Set(info, New("depth").ToLocalChecked(), New<v8::String>(baton->depth).ToLocalChecked());
+      if (baton->density > 0) {
+        Set(info, New("density").ToLocalChecked(), New<v8::Uint32>(baton->density));
+      }
+      if (!baton->chromaSubsampling.empty()) {
+        Set(info,
+          New("chromaSubsampling").ToLocalChecked(),
+          New<v8::String>(baton->chromaSubsampling).ToLocalChecked());
+      }
+      Set(info, New("isProgressive").ToLocalChecked(), New<v8::Boolean>(baton->isProgressive));
+      if (baton->paletteBitDepth > 0) {
+        Set(info, New("paletteBitDepth").ToLocalChecked(), New<v8::Uint32>(baton->paletteBitDepth));
+      }
+      if (baton->pages > 0) {
+        Set(info, New("pages").ToLocalChecked(), New<v8::Uint32>(baton->pages));
+      }
+      if (baton->pageHeight > 0) {
+        Set(info, New("pageHeight").ToLocalChecked(), New<v8::Uint32>(baton->pageHeight));
+      }
+      Set(info, New("hasProfile").ToLocalChecked(), New<v8::Boolean>(baton->hasProfile));
+      Set(info, New("hasAlpha").ToLocalChecked(), New<v8::Boolean>(baton->hasAlpha));
       if (baton->orientation > 0) {
-        info->Set(NanNew<String>("orientation"), NanNew<Number>(baton->orientation));
+        Set(info, New("orientation").ToLocalChecked(), New<v8::Uint32>(baton->orientation));
+      }
+      if (baton->exifLength > 0) {
+        Set(info,
+          New("exif").ToLocalChecked(),
+          Nan::NewBuffer(baton->exif, baton->exifLength, sharp::FreeCallback, nullptr).ToLocalChecked());
+      }
+      if (baton->iccLength > 0) {
+        Set(info,
+          New("icc").ToLocalChecked(),
+          Nan::NewBuffer(baton->icc, baton->iccLength, sharp::FreeCallback, nullptr).ToLocalChecked());
+      }
+      if (baton->iptcLength > 0) {
+        Set(info,
+          New("iptc").ToLocalChecked(),
+          Nan::NewBuffer(baton->iptc, baton->iptcLength, sharp::FreeCallback, nullptr).ToLocalChecked());
+      }
+      if (baton->xmpLength > 0) {
+        Set(info,
+          New("xmp").ToLocalChecked(),
+          Nan::NewBuffer(baton->xmp, baton->xmpLength, sharp::FreeCallback, nullptr).ToLocalChecked());
       }
       argv[1] = info;
     }
+
+    // Dispose of Persistent wrapper around input Buffers so they can be garbage collected
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        GetFromPersistent(index);
+        return index + 1;
+      });
+    delete baton->input;
     delete baton;
 
+    // Handle warnings
+    std::string warning = sharp::VipsWarningPop();
+    while (!warning.empty()) {
+      v8::Local<v8::Value> message[1] = { New(warning).ToLocalChecked() };
+      debuglog->Call(1, message, async_resource);
+      warning = sharp::VipsWarningPop();
+    }
+
     // Return to JavaScript
-    callback->Call(2, argv);
+    callback->Call(2, argv, async_resource);
   }
 
  private:
   MetadataBaton* baton;
+  Nan::Callback *debuglog;
+  std::vector<v8::Local<v8::Object>> buffersToPersist;
 };
 
 /*
   metadata(options, callback)
 */
 NAN_METHOD(metadata) {
-  NanScope();
+  // Input Buffers must not undergo GC compaction during processing
+  std::vector<v8::Local<v8::Object>> buffersToPersist;
 
   // V8 objects are converted to non-V8 types held in the baton struct
   MetadataBaton *baton = new MetadataBaton;
-  Local<Object> options = args[0]->ToObject();
+  v8::Local<v8::Object> options = info[0].As<v8::Object>();
 
-  // Input filename
-  baton->fileIn = *String::Utf8Value(options->Get(NanNew<String>("fileIn"))->ToString());
-  // Input Buffer object
-  if (options->Get(NanNew<String>("bufferIn"))->IsObject()) {
-    Local<Object> buffer = options->Get(NanNew<String>("bufferIn"))->ToObject();
-    baton->bufferInLength = node::Buffer::Length(buffer);
-    baton->bufferIn = node::Buffer::Data(buffer);
-  }
+  // Input
+  baton->input = sharp::CreateInputDescriptor(sharp::AttrAs<v8::Object>(options, "input"), buffersToPersist);
+
+  // Function to notify of libvips warnings
+  Nan::Callback *debuglog = new Nan::Callback(sharp::AttrAs<v8::Function>(options, "debuglog"));
 
   // Join queue for worker thread
-  NanCallback *callback = new NanCallback(args[1].As<v8::Function>());
-  NanAsyncQueueWorker(new MetadataWorker(callback, baton));
+  Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
+  Nan::AsyncQueueWorker(new MetadataWorker(callback, baton, debuglog, buffersToPersist));
 
   // Increment queued task counter
-  g_atomic_int_inc(&counterQueue);
-
-  NanReturnUndefined();
+  g_atomic_int_inc(&sharp::counterQueue);
 }

src/metadata.h

@@ -1,8 +1,77 @@
-#ifndef SHARP_METADATA_H
-#define SHARP_METADATA_H
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
-#include "nan.h"
+#ifndef SRC_METADATA_H_
+#define SRC_METADATA_H_
+
+#include <string>
+#include <nan.h>
+
+#include "./common.h"
+
+struct MetadataBaton {
+  // Input
+  sharp::InputDescriptor *input;
+  // Output
+  std::string format;
+  int width;
+  int height;
+  std::string space;
+  int channels;
+  std::string depth;
+  int density;
+  std::string chromaSubsampling;
+  bool isProgressive;
+  int paletteBitDepth;
+  int pages;
+  int pageHeight;
+  bool hasProfile;
+  bool hasAlpha;
+  int orientation;
+  char *exif;
+  size_t exifLength;
+  char *icc;
+  size_t iccLength;
+  char *iptc;
+  size_t iptcLength;
+  char *xmp;
+  size_t xmpLength;
+  std::string err;
+
+  MetadataBaton():
+    input(nullptr),
+    width(0),
+    height(0),
+    channels(0),
+    density(0),
+    isProgressive(false),
+    paletteBitDepth(0),
+    pages(0),
+    pageHeight(0),
+    hasProfile(false),
+    hasAlpha(false),
+    orientation(0),
+    exif(nullptr),
+    exifLength(0),
+    icc(nullptr),
+    iccLength(0),
+    iptc(nullptr),
+    iptcLength(0),
+    xmp(nullptr),
+    xmpLength(0) {}
+};
 
 NAN_METHOD(metadata);
 
-#endif
+#endif  // SRC_METADATA_H_

src/operations.cc

@@ -0,0 +1,265 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vector>
+
+#include <vips/vips8>
+
+#include "common.h"
+#include "operations.h"
+
+using vips::VImage;
+using vips::VError;
+
+namespace sharp {
+
+  /*
+    Removes alpha channel, if any.
+  */
+  VImage RemoveAlpha(VImage image) {
+    if (HasAlpha(image)) {
+      image = image.extract_band(0, VImage::option()->set("n", image.bands() - 1));
+    }
+    return image;
+  }
+
+  /*
+    Ensures alpha channel, if missing.
+  */
+  VImage EnsureAlpha(VImage image) {
+    if (!HasAlpha(image)) {
+      std::vector<double> alpha;
+      alpha.push_back(sharp::MaximumImageAlpha(image.interpretation()));
+      image = image.bandjoin_const(alpha);
+    }
+    return image;
+  }
+
+  /*
+   * Tint an image using the specified chroma, preserving the original image luminance
+   */
+  VImage Tint(VImage image, double const a, double const b) {
+    // Get original colourspace
+    VipsInterpretation typeBeforeTint = image.interpretation();
+    if (typeBeforeTint == VIPS_INTERPRETATION_RGB) {
+      typeBeforeTint = VIPS_INTERPRETATION_sRGB;
+    }
+    // Extract luminance
+    VImage luminance = image.colourspace(VIPS_INTERPRETATION_LAB)[0];
+    // Create the tinted version by combining the L from the original and the chroma from the tint
+    std::vector<double> chroma {a, b};
+    VImage tinted = luminance
+      .bandjoin(chroma)
+      .copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_LAB))
+      .colourspace(typeBeforeTint);
+    // Attach original alpha channel, if any
+    if (HasAlpha(image)) {
+      // Extract original alpha channel
+      VImage alpha = image[image.bands() - 1];
+      // Join alpha channel to normalised image
+      tinted = tinted.bandjoin(alpha);
+    }
+    return tinted;
+  }
+
+  /*
+   * Stretch luminance to cover full dynamic range.
+   */
+  VImage Normalise(VImage image) {
+    // Get original colourspace
+    VipsInterpretation typeBeforeNormalize = image.interpretation();
+    if (typeBeforeNormalize == VIPS_INTERPRETATION_RGB) {
+      typeBeforeNormalize = VIPS_INTERPRETATION_sRGB;
+    }
+    // Convert to LAB colourspace
+    VImage lab = image.colourspace(VIPS_INTERPRETATION_LAB);
+    // Extract luminance
+    VImage luminance = lab[0];
+    // Find luminance range
+    VImage stats = luminance.stats();
+    double min = stats(0, 0)[0];
+    double max = stats(1, 0)[0];
+    if (min != max) {
+      // Extract chroma
+      VImage chroma = lab.extract_band(1, VImage::option()->set("n", 2));
+      // Calculate multiplication factor and addition
+      double f = 100.0 / (max - min);
+      double a = -(min * f);
+      // Scale luminance, join to chroma, convert back to original colourspace
+      VImage normalized = luminance.linear(f, a).bandjoin(chroma).colourspace(typeBeforeNormalize);
+      // Attach original alpha channel, if any
+      if (HasAlpha(image)) {
+        // Extract original alpha channel
+        VImage alpha = image[image.bands() - 1];
+        // Join alpha channel to normalised image
+        return normalized.bandjoin(alpha);
+      } else {
+        return normalized;
+      }
+    }
+    return image;
+  }
+
+  /*
+   * Gamma encoding/decoding
+   */
+  VImage Gamma(VImage image, double const exponent) {
+    if (HasAlpha(image)) {
+      // Separate alpha channel
+      VImage alpha = image[image.bands() - 1];
+      return RemoveAlpha(image).gamma(VImage::option()->set("exponent", exponent)).bandjoin(alpha);
+    } else {
+      return image.gamma(VImage::option()->set("exponent", exponent));
+    }
+  }
+
+  /*
+   * Gaussian blur. Use sigma of -1.0 for fast blur.
+   */
+  VImage Blur(VImage image, double const sigma) {
+    if (sigma == -1.0) {
+      // Fast, mild blur - averages neighbouring pixels
+      VImage blur = VImage::new_matrixv(3, 3,
+        1.0, 1.0, 1.0,
+        1.0, 1.0, 1.0,
+        1.0, 1.0, 1.0);
+      blur.set("scale", 9.0);
+      return image.conv(blur);
+    } else {
+      // Slower, accurate Gaussian blur
+      return image.gaussblur(sigma);
+    }
+  }
+
+  /*
+   * Convolution with a kernel.
+   */
+  VImage Convolve(VImage image, int const width, int const height,
+    double const scale, double const offset,
+    std::unique_ptr<double[]> const &kernel_v
+  ) {
+    VImage kernel = VImage::new_from_memory(
+      kernel_v.get(),
+      width * height * sizeof(double),
+      width,
+      height,
+      1,
+      VIPS_FORMAT_DOUBLE);
+    kernel.set("scale", scale);
+    kernel.set("offset", offset);
+
+    return image.conv(kernel);
+  }
+
+  /*
+   * Recomb with a Matrix of the given bands/channel size.
+   * Eg. RGB will be a 3x3 matrix.
+   */
+  VImage Recomb(VImage image, std::unique_ptr<double[]> const &matrix) {
+    double *m = matrix.get();
+    return image
+      .colourspace(VIPS_INTERPRETATION_sRGB)
+      .recomb(image.bands() == 3
+        ? VImage::new_from_memory(
+          m, 9 * sizeof(double), 3, 3, 1, VIPS_FORMAT_DOUBLE
+        )
+        : VImage::new_matrixv(4, 4,
+          m[0], m[1], m[2], 0.0,
+          m[3], m[4], m[5], 0.0,
+          m[6], m[7], m[8], 0.0,
+          0.0, 0.0, 0.0, 1.0));
+  }
+
+  /*
+   * Sharpen flat and jagged areas. Use sigma of -1.0 for fast sharpen.
+   */
+  VImage Sharpen(VImage image, double const sigma, double const flat, double const jagged) {
+    if (sigma == -1.0) {
+      // Fast, mild sharpen
+      VImage sharpen = VImage::new_matrixv(3, 3,
+        -1.0, -1.0, -1.0,
+        -1.0, 32.0, -1.0,
+        -1.0, -1.0, -1.0);
+      sharpen.set("scale", 24.0);
+      return image.conv(sharpen);
+    } else {
+      // Slow, accurate sharpen in LAB colour space, with control over flat vs jagged areas
+      VipsInterpretation colourspaceBeforeSharpen = image.interpretation();
+      if (colourspaceBeforeSharpen == VIPS_INTERPRETATION_RGB) {
+        colourspaceBeforeSharpen = VIPS_INTERPRETATION_sRGB;
+      }
+      return image.sharpen(
+        VImage::option()->set("sigma", sigma)->set("m1", flat)->set("m2", jagged))
+        .colourspace(colourspaceBeforeSharpen);
+    }
+  }
+
+  VImage Threshold(VImage image, double const threshold, bool const thresholdGrayscale) {
+    if (!thresholdGrayscale) {
+      return image >= threshold;
+    }
+    return image.colourspace(VIPS_INTERPRETATION_B_W) >= threshold;
+  }
+
+  /*
+    Perform boolean/bitwise operation on image color channels - results in one channel image
+  */
+  VImage Bandbool(VImage image, VipsOperationBoolean const boolean) {
+    image = image.bandbool(boolean);
+    return image.copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_B_W));
+  }
+
+  /*
+    Perform bitwise boolean operation between images
+  */
+  VImage Boolean(VImage image, VImage imageR, VipsOperationBoolean const boolean) {
+    return image.boolean(imageR, boolean);
+  }
+
+  /*
+    Trim an image
+  */
+  VImage Trim(VImage image, double const threshold) {
+    // Top-left pixel provides the background colour
+    VImage background = image.extract_area(0, 0, 1, 1);
+    if (HasAlpha(background)) {
+      background = background.flatten();
+    }
+    int top, width, height;
+    int const left = image.find_trim(&top, &width, &height, VImage::option()
+      ->set("background", background(0, 0))
+      ->set("threshold", threshold));
+    if (width == 0 || height == 0) {
+      throw VError("Unexpected error while trimming. Try to lower the tolerance");
+    }
+    return image.extract_area(left, top, width, height);
+  }
+
+  /*
+   * Calculate (a * in + b)
+   */
+  VImage Linear(VImage image, double const a, double const b) {
+    if (HasAlpha(image)) {
+      // Separate alpha channel
+      VImage alpha = image[image.bands() - 1];
+      return RemoveAlpha(image).linear(a, b).bandjoin(alpha);
+    } else {
+      return image.linear(a, b);
+    }
+  }
+}  // namespace sharp

src/operations.h

@@ -0,0 +1,102 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_OPERATIONS_H_
+#define SRC_OPERATIONS_H_
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vips/vips8>
+
+using vips::VImage;
+
+namespace sharp {
+
+  /*
+    Removes alpha channel, if any.
+  */
+  VImage RemoveAlpha(VImage image);
+
+  /*
+    Ensures alpha channel, if missing.
+  */
+  VImage EnsureAlpha(VImage image);
+
+  /*
+   * Tint an image using the specified chroma, preserving the original image luminance
+   */
+  VImage Tint(VImage image, double const a, double const b);
+
+  /*
+   * Stretch luminance to cover full dynamic range.
+   */
+  VImage Normalise(VImage image);
+
+  /*
+   * Gamma encoding/decoding
+   */
+  VImage Gamma(VImage image, double const exponent);
+
+  /*
+   * Gaussian blur. Use sigma of -1.0 for fast blur.
+   */
+  VImage Blur(VImage image, double const sigma);
+
+  /*
+   * Convolution with a kernel.
+   */
+  VImage Convolve(VImage image, int const width, int const height,
+    double const scale, double const offset, std::unique_ptr<double[]> const &kernel_v);
+
+  /*
+   * Sharpen flat and jagged areas. Use sigma of -1.0 for fast sharpen.
+   */
+  VImage Sharpen(VImage image, double const sigma, double const flat, double const jagged);
+
+  /*
+    Threshold an image
+  */
+  VImage Threshold(VImage image, double const threshold, bool const thresholdColor);
+
+  /*
+    Perform boolean/bitwise operation on image color channels - results in one channel image
+  */
+  VImage Bandbool(VImage image, VipsOperationBoolean const boolean);
+
+  /*
+    Perform bitwise boolean operation between images
+  */
+  VImage Boolean(VImage image, VImage imageR, VipsOperationBoolean const boolean);
+
+  /*
+    Trim an image
+  */
+  VImage Trim(VImage image, double const threshold);
+
+  /*
+   * Linear adjustment (a * in + b)
+   */
+  VImage Linear(VImage image, double const a, double const b);
+
+  /*
+   * Recomb with a Matrix of the given bands/channel size.
+   * Eg. RGB will be a 3x3 matrix.
+   */
+  VImage Recomb(VImage image, std::unique_ptr<double[]> const &matrix);
+
+}  // namespace sharp
+
+#endif  // SRC_OPERATIONS_H_

src/pipeline.h

@@ -0,0 +1,265 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_PIPELINE_H_
+#define SRC_PIPELINE_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <nan.h>
+#include <vips/vips8>
+
+#include "./common.h"
+
+NAN_METHOD(pipeline);
+
+enum class Canvas {
+  CROP,
+  EMBED,
+  MAX,
+  MIN,
+  IGNORE_ASPECT
+};
+
+struct Composite {
+  sharp::InputDescriptor *input;
+  VipsBlendMode mode;
+  int gravity;
+  int left;
+  int top;
+  bool tile;
+
+  Composite():
+    input(nullptr),
+    mode(VIPS_BLEND_MODE_OVER),
+    gravity(0),
+    left(-1),
+    top(-1),
+    tile(false) {}
+};
+
+struct PipelineBaton {
+  sharp::InputDescriptor *input;
+  std::string iccProfilePath;
+  int limitInputPixels;
+  std::string formatOut;
+  std::string fileOut;
+  void *bufferOut;
+  size_t bufferOutLength;
+  std::vector<Composite *> composite;
+  std::vector<sharp::InputDescriptor *> joinChannelIn;
+  int topOffsetPre;
+  int leftOffsetPre;
+  int widthPre;
+  int heightPre;
+  int topOffsetPost;
+  int leftOffsetPost;
+  int widthPost;
+  int heightPost;
+  int width;
+  int height;
+  int channels;
+  Canvas canvas;
+  int position;
+  std::vector<double> resizeBackground;
+  bool hasCropOffset;
+  int cropOffsetLeft;
+  int cropOffsetTop;
+  bool premultiplied;
+  std::string kernel;
+  bool fastShrinkOnLoad;
+  double tintA;
+  double tintB;
+  bool flatten;
+  std::vector<double> flattenBackground;
+  bool negate;
+  double blurSigma;
+  int medianSize;
+  double sharpenSigma;
+  double sharpenFlat;
+  double sharpenJagged;
+  int threshold;
+  bool thresholdGrayscale;
+  double trimThreshold;
+  int trimOffsetLeft;
+  int trimOffsetTop;
+  double linearA;
+  double linearB;
+  double gamma;
+  double gammaOut;
+  bool greyscale;
+  bool normalise;
+  bool useExifOrientation;
+  int angle;
+  double rotationAngle;
+  std::vector<double> rotationBackground;
+  bool rotateBeforePreExtract;
+  bool flip;
+  bool flop;
+  int extendTop;
+  int extendBottom;
+  int extendLeft;
+  int extendRight;
+  std::vector<double> extendBackground;
+  bool withoutEnlargement;
+  VipsAccess accessMethod;
+  int jpegQuality;
+  bool jpegProgressive;
+  std::string jpegChromaSubsampling;
+  bool jpegTrellisQuantisation;
+  int jpegQuantisationTable;
+  bool jpegOvershootDeringing;
+  bool jpegOptimiseScans;
+  bool jpegOptimiseCoding;
+  bool pngProgressive;
+  int pngCompressionLevel;
+  bool pngAdaptiveFiltering;
+  bool pngPalette;
+  int pngQuality;
+  int pngColours;
+  double pngDither;
+  int webpQuality;
+  int webpAlphaQuality;
+  bool webpNearLossless;
+  bool webpLossless;
+  int tiffQuality;
+  VipsForeignTiffCompression tiffCompression;
+  VipsForeignTiffPredictor tiffPredictor;
+  bool tiffPyramid;
+  bool tiffSquash;
+  bool tiffTile;
+  int tiffTileHeight;
+  int tiffTileWidth;
+  double tiffXres;
+  double tiffYres;
+  std::string err;
+  bool withMetadata;
+  int withMetadataOrientation;
+  std::unique_ptr<double[]> convKernel;
+  int convKernelWidth;
+  int convKernelHeight;
+  double convKernelScale;
+  double convKernelOffset;
+  sharp::InputDescriptor *boolean;
+  VipsOperationBoolean booleanOp;
+  VipsOperationBoolean bandBoolOp;
+  int extractChannel;
+  bool removeAlpha;
+  bool ensureAlpha;
+  VipsInterpretation colourspace;
+  int tileSize;
+  int tileOverlap;
+  VipsForeignDzContainer tileContainer;
+  VipsForeignDzLayout tileLayout;
+  std::string tileFormat;
+  int tileAngle;
+  VipsForeignDzDepth tileDepth;
+  std::unique_ptr<double[]> recombMatrix;
+
+  PipelineBaton():
+    input(nullptr),
+    limitInputPixels(0),
+    bufferOutLength(0),
+    topOffsetPre(-1),
+    topOffsetPost(-1),
+    channels(0),
+    canvas(Canvas::CROP),
+    position(0),
+    resizeBackground{ 0.0, 0.0, 0.0, 255.0 },
+    hasCropOffset(false),
+    cropOffsetLeft(0),
+    cropOffsetTop(0),
+    premultiplied(false),
+    tintA(128.0),
+    tintB(128.0),
+    flatten(false),
+    flattenBackground{ 0.0, 0.0, 0.0 },
+    negate(false),
+    blurSigma(0.0),
+    medianSize(0),
+    sharpenSigma(0.0),
+    sharpenFlat(1.0),
+    sharpenJagged(2.0),
+    threshold(0),
+    thresholdGrayscale(true),
+    trimThreshold(0.0),
+    trimOffsetLeft(0),
+    trimOffsetTop(0),
+    linearA(1.0),
+    linearB(0.0),
+    gamma(0.0),
+    greyscale(false),
+    normalise(false),
+    useExifOrientation(false),
+    angle(0),
+    rotationAngle(0.0),
+    rotationBackground{ 0.0, 0.0, 0.0, 255.0 },
+    flip(false),
+    flop(false),
+    extendTop(0),
+    extendBottom(0),
+    extendLeft(0),
+    extendRight(0),
+    extendBackground{ 0.0, 0.0, 0.0, 255.0 },
+    withoutEnlargement(false),
+    jpegQuality(80),
+    jpegProgressive(false),
+    jpegChromaSubsampling("4:2:0"),
+    jpegTrellisQuantisation(false),
+    jpegQuantisationTable(0),
+    jpegOvershootDeringing(false),
+    jpegOptimiseScans(false),
+    jpegOptimiseCoding(true),
+    pngProgressive(false),
+    pngCompressionLevel(9),
+    pngAdaptiveFiltering(false),
+    pngPalette(false),
+    pngQuality(100),
+    pngColours(256),
+    pngDither(1.0),
+    webpQuality(80),
+    tiffQuality(80),
+    tiffCompression(VIPS_FOREIGN_TIFF_COMPRESSION_JPEG),
+    tiffPredictor(VIPS_FOREIGN_TIFF_PREDICTOR_HORIZONTAL),
+    tiffPyramid(false),
+    tiffSquash(false),
+    tiffTile(false),
+    tiffTileHeight(256),
+    tiffTileWidth(256),
+    tiffXres(1.0),
+    tiffYres(1.0),
+    withMetadata(false),
+    withMetadataOrientation(-1),
+    convKernelWidth(0),
+    convKernelHeight(0),
+    convKernelScale(0.0),
+    convKernelOffset(0.0),
+    boolean(nullptr),
+    booleanOp(VIPS_OPERATION_BOOLEAN_LAST),
+    bandBoolOp(VIPS_OPERATION_BOOLEAN_LAST),
+    extractChannel(-1),
+    removeAlpha(false),
+    ensureAlpha(false),
+    colourspace(VIPS_INTERPRETATION_LAST),
+    tileSize(256),
+    tileOverlap(0),
+    tileContainer(VIPS_FOREIGN_DZ_CONTAINER_FS),
+    tileLayout(VIPS_FOREIGN_DZ_LAYOUT_DZ),
+    tileAngle(0),
+    tileDepth(VIPS_FOREIGN_DZ_DEPTH_LAST) {}
+};
+
+#endif  // SRC_PIPELINE_H_

src/resize.cc

@@ -1,876 +0,0 @@
-#include <tuple>
-#include <algorithm>
-#include <cmath>
-#include <node.h>
-#include <node_buffer.h>
-#include <vips/vips.h>
-
-#include "nan.h"
-
-#include "common.h"
-#include "resize.h"
-
-using namespace v8;
-using namespace sharp;
-
-enum class Canvas {
-  CROP,
-  MAX,
-  EMBED
-};
-
-enum class Angle {
-	D0,
-	D90,
-	D180,
-	D270,
-	DLAST
-};
-
-struct ResizeBaton {
-  std::string fileIn;
-  void* bufferIn;
-  size_t bufferInLength;
-  std::string iccProfileCmyk;
-  std::string output;
-  std::string outputFormat;
-  void* bufferOut;
-  size_t bufferOutLength;
-  int topOffsetPre;
-  int leftOffsetPre;
-  int widthPre;
-  int heightPre;
-  int topOffsetPost;
-  int leftOffsetPost;
-  int widthPost;
-  int heightPost;
-  int width;
-  int height;
-  Canvas canvas;
-  int gravity;
-  std::string interpolator;
-  double background[4];
-  bool flatten;
-  int blurRadius;
-  int sharpenRadius;
-  double sharpenFlat;
-  double sharpenJagged;
-  double gamma;
-  bool greyscale;
-  int angle;
-  bool flip;
-  bool flop;
-  bool progressive;
-  bool withoutEnlargement;
-  VipsAccess accessMethod;
-  int quality;
-  int compressionLevel;
-  bool withoutAdaptiveFiltering;
-  std::string err;
-  bool withMetadata;
-
-  ResizeBaton():
-    bufferInLength(0),
-    outputFormat(""),
-    bufferOutLength(0),
-    topOffsetPre(-1),
-    topOffsetPost(-1),
-    canvas(Canvas::CROP),
-    gravity(0),
-    flatten(false),
-    blurRadius(0),
-    sharpenRadius(0),
-    sharpenFlat(1.0),
-    sharpenJagged(2.0),
-    gamma(0.0),
-    greyscale(false),
-    angle(0),
-    flip(false),
-    flop(false),
-    progressive(false),
-    withoutEnlargement(false),
-    quality(80),
-    compressionLevel(6),
-    withoutAdaptiveFiltering(false),
-    withMetadata(false) {
-      background[0] = 0.0;
-      background[1] = 0.0;
-      background[2] = 0.0;
-      background[3] = 255.0;
-    }
-};
-
-class ResizeWorker : public NanAsyncWorker {
-
- public:
-  ResizeWorker(NanCallback *callback, ResizeBaton *baton) : NanAsyncWorker(callback), baton(baton) {}
-  ~ResizeWorker() {}
-
-  /*
-    libuv worker
-  */
-  void Execute() {
-    // Decrement queued task counter
-    g_atomic_int_dec_and_test(&counterQueue);
-    // Increment processing task counter
-    g_atomic_int_inc(&counterProcess);
-
-    // Hang image references from this hook object
-    VipsObject *hook = reinterpret_cast<VipsObject*>(vips_image_new());
-
-    // Input
-    ImageType inputImageType = ImageType::UNKNOWN;
-    VipsImage *image;
-    if (baton->bufferInLength > 1) {
-      // From buffer
-      inputImageType = DetermineImageType(baton->bufferIn, baton->bufferInLength);
-      if (inputImageType != ImageType::UNKNOWN) {
-        image = InitImage(inputImageType, baton->bufferIn, baton->bufferInLength, baton->accessMethod);
-      } else {
-        (baton->err).append("Input buffer contains unsupported image format");
-      }
-    } else {
-      // From file
-      inputImageType = DetermineImageType(baton->fileIn.c_str());
-      if (inputImageType != ImageType::UNKNOWN) {
-        image = InitImage(inputImageType, baton->fileIn.c_str(), baton->accessMethod);
-      } else {
-        (baton->err).append("File is of an unsupported image format");
-      }
-    }
-    if (inputImageType == ImageType::UNKNOWN) {
-      return Error(baton, hook);
-    }
-    vips_object_local(hook, image);
-
-    // Pre extraction
-    if (baton->topOffsetPre != -1) {
-      VipsImage *extractedPre;
-      if (vips_extract_area(image, &extractedPre, baton->leftOffsetPre, baton->topOffsetPre, baton->widthPre, baton->heightPre, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, extractedPre);
-      image = extractedPre;
-    }
-
-    // Get input image width and height
-    int inputWidth = image->Xsize;
-    int inputHeight = image->Ysize;
-
-    // Calculate angle of rotation, to be carried out later
-    Angle rotation;
-    bool flip;
-    std::tie(rotation, flip) = CalculateRotationAndFlip(baton->angle, image);
-    if (rotation == Angle::D90 || rotation == Angle::D270) {
-      // Swap input output width and height when rotating by 90 or 270 degrees
-      int swap = inputWidth;
-      inputWidth = inputHeight;
-      inputHeight = swap;
-    }
-    if (flip && !baton->flip) {
-      // Add flip operation due to EXIF mirroring
-      baton->flip = TRUE;
-    }
-
-    // Get window size of interpolator, used for determining shrink vs affine
-    int interpolatorWindowSize = InterpolatorWindowSize(baton->interpolator.c_str());
-
-    // Scaling calculations
-    double factor;
-    if (baton->width > 0 && baton->height > 0) {
-      // Fixed width and height
-      double xfactor = static_cast<double>(inputWidth) / static_cast<double>(baton->width);
-      double yfactor = static_cast<double>(inputHeight) / static_cast<double>(baton->height);
-      factor = (baton->canvas == Canvas::CROP) ? std::min(xfactor, yfactor) : std::max(xfactor, yfactor);
-      // if max is set, we need to compute the real size of the thumb image
-      if (baton->canvas == Canvas::MAX) {
-        if (xfactor > yfactor) {
-          baton->height = round(static_cast<double>(inputHeight) / xfactor);
-        } else {
-          baton->width = round(static_cast<double>(inputWidth) / yfactor);
-        }
-      }
-    } else if (baton->width > 0) {
-      // Fixed width, auto height
-      factor = static_cast<double>(inputWidth) / static_cast<double>(baton->width);
-      baton->height = floor(static_cast<double>(inputHeight) / factor);
-    } else if (baton->height > 0) {
-      // Fixed height, auto width
-      factor = static_cast<double>(inputHeight) / static_cast<double>(baton->height);
-      baton->width = floor(static_cast<double>(inputWidth) / factor);
-    } else {
-      // Identity transform
-      factor = 1;
-      baton->width = inputWidth;
-      baton->height = inputHeight;
-    }
-
-    // Calculate integral box shrink
-    int shrink = 1;
-    if (factor >= 2 && interpolatorWindowSize > 3) {
-      // Shrink less, affine more with interpolators that use at least 4x4 pixel window, e.g. bicubic
-      shrink = floor(factor * 3.0 / interpolatorWindowSize);
-    } else {
-      shrink = floor(factor);
-    }
-    if (shrink < 1) {
-      shrink = 1;
-    }
-
-    // Calculate residual float affine transformation
-    double residual = static_cast<double>(shrink) / factor;
-
-    // Do not enlarge the output if the input width *or* height are already less than the required dimensions
-    if (baton->withoutEnlargement) {
-      if (inputWidth < baton->width || inputHeight < baton->height) {
-        factor = 1;
-        shrink = 1;
-        residual = 0;
-        baton->width = inputWidth;
-        baton->height = inputHeight;
-      }
-    }
-
-    // Try to use libjpeg shrink-on-load, but not when applying gamma correction or pre-resize extract
-    int shrink_on_load = 1;
-    if (inputImageType == ImageType::JPEG && shrink >= 2 && baton->gamma == 0 && baton->topOffsetPre == -1) {
-      if (shrink >= 8) {
-        factor = factor / 8;
-        shrink_on_load = 8;
-      } else if (shrink >= 4) {
-        factor = factor / 4;
-        shrink_on_load = 4;
-      } else if (shrink >= 2) {
-        factor = factor / 2;
-        shrink_on_load = 2;
-      }
-    }
-    if (shrink_on_load > 1) {
-      // Recalculate integral shrink and double residual
-      factor = std::max(factor, 1.0);
-      if (factor >= 2 && interpolatorWindowSize > 3) {
-        shrink = floor(factor * 3.0 / interpolatorWindowSize);
-      } else {
-        shrink = floor(factor);
-      }
-      residual = static_cast<double>(shrink) / factor;
-      // Reload input using shrink-on-load
-      VipsImage *shrunkOnLoad;
-      if (baton->bufferInLength > 1) {
-        if (vips_jpegload_buffer(baton->bufferIn, baton->bufferInLength, &shrunkOnLoad, "shrink", shrink_on_load, NULL)) {
-          return Error(baton, hook);
-        }
-      } else {
-        if (vips_jpegload((baton->fileIn).c_str(), &shrunkOnLoad, "shrink", shrink_on_load, NULL)) {
-          return Error(baton, hook);
-        }
-      }
-      vips_object_local(hook, shrunkOnLoad);
-      image = shrunkOnLoad;
-    }
-
-    // Handle colour profile, if any, for non sRGB images
-    if (image->Type != VIPS_INTERPRETATION_sRGB) {
-      // Get the input colour profile
-      if (vips_image_get_typeof(image, VIPS_META_ICC_NAME)) {
-        VipsImage *profile;
-        // Use embedded profile
-        if (vips_icc_import(image, &profile, "pcs", VIPS_PCS_XYZ, "embedded", TRUE, NULL)) {
-          return Error(baton, hook);
-        }
-        vips_object_local(hook, profile);
-        image = profile;
-      } else if (image->Type == VIPS_INTERPRETATION_CMYK) {
-        VipsImage *profile;
-        // CMYK with no embedded profile
-        if (vips_icc_import(image, &profile, "pcs", VIPS_PCS_XYZ, "input_profile", (baton->iccProfileCmyk).c_str(), NULL)) {
-          return Error(baton, hook);
-        }
-        vips_object_local(hook, profile);
-        image = profile;
-      }
-      // Attempt to convert to sRGB colour space
-      VipsImage *colourspaced;
-      if (vips_colourspace(image, &colourspaced, VIPS_INTERPRETATION_sRGB, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, colourspaced);
-      image = colourspaced;
-    }
-
-    // Flatten image to remove alpha channel
-    if (baton->flatten && HasAlpha(image)) {
-      // Background colour
-      VipsArrayDouble *background = vips_array_double_newv(
-        3, // Ignore alpha channel as we're about to remove it
-        baton->background[0],
-        baton->background[1],
-        baton->background[2]
-      );
-      VipsImage *flattened;
-      if (vips_flatten(image, &flattened, "background", background, NULL)) {
-        vips_area_unref(reinterpret_cast<VipsArea*>(background));
-        return Error(baton, hook);
-      };
-      vips_area_unref(reinterpret_cast<VipsArea*>(background));
-      vips_object_local(hook, flattened);
-      image = flattened;
-    }
-
-    // Gamma encoding (darken)
-    if (baton->gamma >= 1 && baton->gamma <= 3) {
-      VipsImage *gammaEncoded;
-      if (vips_gamma(image, &gammaEncoded, "exponent", 1.0 / baton->gamma, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, gammaEncoded);
-      image = gammaEncoded;
-    }
-
-    // Convert to greyscale (linear, therefore after gamma encoding, if any)
-    if (baton->greyscale) {
-      VipsImage *greyscale;
-      if (vips_colourspace(image, &greyscale, VIPS_INTERPRETATION_B_W, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, greyscale);
-      image = greyscale;
-    }
-
-    if (shrink > 1) {
-      VipsImage *shrunk;
-      // Use vips_shrink with the integral reduction
-      if (vips_shrink(image, &shrunk, shrink, shrink, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, shrunk);
-      image = shrunk;
-      // Recalculate residual float based on dimensions of required vs shrunk images
-      double shrunkWidth = shrunk->Xsize;
-      double shrunkHeight = shrunk->Ysize;
-      if (rotation == Angle::D90 || rotation == Angle::D270) {
-        // Swap input output width and height when rotating by 90 or 270 degrees
-        int swap = shrunkWidth;
-        shrunkWidth = shrunkHeight;
-        shrunkHeight = swap;
-      }
-      double residualx = static_cast<double>(baton->width) / static_cast<double>(shrunkWidth);
-      double residualy = static_cast<double>(baton->height) / static_cast<double>(shrunkHeight);
-      if (baton->canvas == Canvas::EMBED) {
-        residual = std::min(residualx, residualy);
-      } else {
-        residual = std::max(residualx, residualy);
-      }
-    }
-
-    // Use vips_affine with the remaining float part
-    if (residual != 0) {
-      // Apply variable blur radius of floor(residual) before large affine reductions
-      if (residual >= 1) {
-        VipsImage *blurred;
-        if (vips_gaussblur(image, &blurred, floor(residual), NULL)) {
-          return Error(baton, hook);
-        }
-        vips_object_local(hook, blurred);
-        image = blurred;
-      }
-      // Create interpolator - "bilinear" (default), "bicubic" or "nohalo"
-      VipsInterpolate *interpolator = vips_interpolate_new(baton->interpolator.c_str());
-      vips_object_local(hook, interpolator);
-      // Perform affine transformation
-      VipsImage *affined;
-      if (vips_affine(image, &affined, residual, 0, 0, residual, "interpolate", interpolator, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, affined);
-      image = affined;
-    }
-
-    // Rotate
-    if (rotation != Angle::D0) {
-      VipsImage *rotated;
-      if (vips_rot(image, &rotated, static_cast<VipsAngle>(rotation), NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, rotated);
-      image = rotated;
-    }
-
-    // Flip (mirror about Y axis)
-    if (baton->flip) {
-      VipsImage *flipped;
-      if (vips_flip(image, &flipped, VIPS_DIRECTION_VERTICAL, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, flipped);
-      image = flipped;
-    }
-
-    // Flop (mirror about X axis)
-    if (baton->flop) {
-      VipsImage *flopped;
-      if (vips_flip(image, &flopped, VIPS_DIRECTION_HORIZONTAL, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, flopped);
-      image = flopped;
-    }
-
-    // Crop/embed
-    if (image->Xsize != baton->width || image->Ysize != baton->height) {
-      if (baton->canvas == Canvas::EMBED) {
-        // Match background colour space, namely sRGB
-        if (image->Type != VIPS_INTERPRETATION_sRGB) {
-          // Convert to sRGB colour space
-          VipsImage *colourspaced;
-          if (vips_colourspace(image, &colourspaced, VIPS_INTERPRETATION_sRGB, NULL)) {
-            return Error(baton, hook);
-          }
-          vips_object_local(hook, colourspaced);
-          image = colourspaced;
-        }
-        // Add non-transparent alpha channel, if required
-        if (baton->background[3] < 255.0 && !HasAlpha(image)) {
-          // Create single-channel transparency
-          VipsImage *black;
-          if (vips_black(&black, image->Xsize, image->Ysize, "bands", 1, NULL)) {
-            return Error(baton, hook);
-          }
-          vips_object_local(hook, black);
-          // Invert to become non-transparent
-          VipsImage *alpha;
-          if (vips_invert(black, &alpha, NULL)) {
-            return Error(baton, hook);
-          }
-          vips_object_local(hook, alpha);
-          // Append alpha channel to existing image
-          VipsImage *joined;
-          if (vips_bandjoin2(image, alpha, &joined, NULL)) {
-            return Error(baton, hook);
-          }
-          vips_object_local(hook, joined);
-          image = joined;
-        }
-        // Create background
-        VipsArrayDouble *background;
-        if (baton->background[3] < 255.0) {
-          background = vips_array_double_newv(
-            4, baton->background[0], baton->background[1], baton->background[2], baton->background[3]
-          );
-        } else {
-          background = vips_array_double_newv(
-            3, baton->background[0], baton->background[1], baton->background[2]
-          );
-        }
-        // Embed
-        int left = (baton->width - image->Xsize) / 2;
-        int top = (baton->height - image->Ysize) / 2;
-        VipsImage *embedded;
-        if (vips_embed(image, &embedded, left, top, baton->width, baton->height,
-          "extend", VIPS_EXTEND_BACKGROUND, "background", background, NULL
-        )) {
-          vips_area_unref(reinterpret_cast<VipsArea*>(background));
-          return Error(baton, hook);
-        }
-        vips_area_unref(reinterpret_cast<VipsArea*>(background));
-        vips_object_local(hook, embedded);
-        image = embedded;
-      } else {
-        // Crop/max
-        int left;
-        int top;
-        std::tie(left, top) = CalculateCrop(image->Xsize, image->Ysize, baton->width, baton->height, baton->gravity);
-        int width = std::min(image->Xsize, baton->width);
-        int height = std::min(image->Ysize, baton->height);
-        VipsImage *extracted;
-        if (vips_extract_area(image, &extracted, left, top, width, height, NULL)) {
-          return Error(baton, hook);
-        }
-        vips_object_local(hook, extracted);
-        image = extracted;
-      }
-    }
-
-    // Post extraction
-    if (baton->topOffsetPost != -1) {
-      VipsImage *extractedPost;
-      if (vips_extract_area(image, &extractedPost, baton->leftOffsetPost, baton->topOffsetPost, baton->widthPost, baton->heightPost, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, extractedPost);
-      image = extractedPost;
-    }
-
-    // Blur
-    if (baton->blurRadius != 0) {
-      VipsImage *blurred;
-      if (baton->blurRadius == -1) {
-        // Fast, mild blur
-        VipsImage *blur = vips_image_new_matrixv(3, 3,
-          1.0, 1.0, 1.0,
-          1.0, 1.0, 1.0,
-          1.0, 1.0, 1.0);
-        vips_image_set_double(blur, "scale", 9);
-        vips_object_local(hook, blur);
-        if (vips_conv(image, &blurred, blur, NULL)) {
-          return Error(baton, hook);
-        }
-      } else {
-        // Slower, accurate Gaussian blur
-        if (vips_gaussblur(image, &blurred, baton->blurRadius, NULL)) {
-          return Error(baton, hook);
-        }
-      }
-      vips_object_local(hook, blurred);
-      image = blurred;
-    }
-
-    // Sharpen
-    if (baton->sharpenRadius != 0) {
-      VipsImage *sharpened;
-      if (baton->sharpenRadius == -1) {
-        // Fast, mild sharpen
-        VipsImage *sharpen = vips_image_new_matrixv(3, 3,
-          -1.0, -1.0, -1.0,
-          -1.0, 32.0, -1.0,
-          -1.0, -1.0, -1.0);
-        vips_image_set_double(sharpen, "scale", 24);
-        vips_object_local(hook, sharpen);
-        if (vips_conv(image, &sharpened, sharpen, NULL)) {
-          return Error(baton, hook);
-        }
-      } else {
-        // Slow, accurate sharpen in LAB colour space, with control over flat vs jagged areas
-        if (vips_sharpen(image, &sharpened, "radius", baton->sharpenRadius, "m1", baton->sharpenFlat, "m2", baton->sharpenJagged, NULL)) {
-          return Error(baton, hook);
-        }
-      }
-      vips_object_local(hook, sharpened);
-      image = sharpened;
-    }
-
-    // Gamma decoding (brighten)
-    if (baton->gamma >= 1 && baton->gamma <= 3) {
-      VipsImage *gammaDecoded;
-      if (vips_gamma(image, &gammaDecoded, "exponent", baton->gamma, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, gammaDecoded);
-      image = gammaDecoded;
-    }
-
-    // Convert to sRGB colour space, if not already
-    if (image->Type != VIPS_INTERPRETATION_sRGB) {
-      VipsImage *colourspaced;
-      if (vips_colourspace(image, &colourspaced, VIPS_INTERPRETATION_sRGB, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, colourspaced);
-      image = colourspaced;
-    }
-
-#if !(VIPS_MAJOR_VERSION >= 7 && VIPS_MINOR_VERSION >= 40 && VIPS_MINOR_VERSION >= 5)
-    // Generate image tile cache when interlace output is required - no longer required as of libvips 7.40.5+
-    if (baton->progressive) {
-      VipsImage *cached;
-      if (vips_tilecache(image, &cached, "threaded", TRUE, "persistent", TRUE, "max_tiles", -1, NULL)) {
-        return Error(baton, hook);
-      }
-      vips_object_local(hook, cached);
-      image = cached;
-    }
-#endif
-
-    // Output
-    if (baton->output == "__jpeg" || (baton->output == "__input" && inputImageType == ImageType::JPEG)) {
-      // Write JPEG to buffer
-      if (vips_jpegsave_buffer(image, &baton->bufferOut, &baton->bufferOutLength, "strip", !baton->withMetadata,
-        "Q", baton->quality, "optimize_coding", TRUE, "interlace", baton->progressive, NULL)) {
-        return Error(baton, hook);
-      }
-      baton->outputFormat = "jpeg";
-    } else if (baton->output == "__png" || (baton->output == "__input" && inputImageType == ImageType::PNG)) {
-#if (VIPS_MAJOR_VERSION >= 7 && VIPS_MINOR_VERSION >= 41)
-      // Select PNG row filter
-      int filter = baton->withoutAdaptiveFiltering ? VIPS_FOREIGN_PNG_FILTER_NONE : VIPS_FOREIGN_PNG_FILTER_ALL;
-      // Write PNG to buffer
-      if (vips_pngsave_buffer(image, &baton->bufferOut, &baton->bufferOutLength, "strip", !baton->withMetadata,
-        "compression", baton->compressionLevel, "interlace", baton->progressive, "filter", filter, NULL)) {
-        return Error(baton, hook);
-      }
-#else
-      // Write PNG to buffer
-      if (vips_pngsave_buffer(image, &baton->bufferOut, &baton->bufferOutLength, "strip", !baton->withMetadata,
-        "compression", baton->compressionLevel, "interlace", baton->progressive, NULL)) {
-        return Error(baton, hook);
-      }
-#endif
-      baton->outputFormat = "png";
-    } else if (baton->output == "__webp" || (baton->output == "__input" && inputImageType == ImageType::WEBP)) {
-      // Write WEBP to buffer
-      if (vips_webpsave_buffer(image, &baton->bufferOut, &baton->bufferOutLength, "strip", !baton->withMetadata,
-        "Q", baton->quality, NULL)) {
-        return Error(baton, hook);
-      }
-      baton->outputFormat = "webp";
-    } else {
-      bool outputJpeg = IsJpeg(baton->output);
-      bool outputPng = IsPng(baton->output);
-      bool outputWebp = IsWebp(baton->output);
-      bool outputTiff = IsTiff(baton->output);
-      bool matchInput = !(outputJpeg || outputPng || outputWebp || outputTiff);
-      if (outputJpeg || (matchInput && inputImageType == ImageType::JPEG)) {
-        // Write JPEG to file
-        if (vips_jpegsave(image, baton->output.c_str(), "strip", !baton->withMetadata,
-          "Q", baton->quality, "optimize_coding", TRUE, "interlace", baton->progressive, NULL)) {
-          return Error(baton, hook);
-        }
-        baton->outputFormat = "jpeg";
-      } else if (outputPng || (matchInput && inputImageType == ImageType::PNG)) {
-#if (VIPS_MAJOR_VERSION >= 7 && VIPS_MINOR_VERSION >= 41)
-        // Select PNG row filter
-        int filter = baton->withoutAdaptiveFiltering ? VIPS_FOREIGN_PNG_FILTER_NONE : VIPS_FOREIGN_PNG_FILTER_ALL;
-        // Write PNG to file
-        if (vips_pngsave(image, baton->output.c_str(), "strip", !baton->withMetadata,
-          "compression", baton->compressionLevel, "interlace", baton->progressive, "filter", filter, NULL)) {
-          return Error(baton, hook);
-        }
-#else
-        // Write PNG to file
-        if (vips_pngsave(image, baton->output.c_str(), "strip", !baton->withMetadata,
-          "compression", baton->compressionLevel, "interlace", baton->progressive, NULL)) {
-          return Error(baton, hook);
-        }
-#endif
-        baton->outputFormat = "png";
-      } else if (outputWebp || (matchInput && inputImageType == ImageType::WEBP)) {
-        // Write WEBP to file
-        if (vips_webpsave(image, baton->output.c_str(), "strip", !baton->withMetadata,
-          "Q", baton->quality, NULL)) {
-          return Error(baton, hook);
-        }
-        baton->outputFormat = "webp";
-      } else if (outputTiff || (matchInput && inputImageType == ImageType::TIFF)) {
-        // Write TIFF to file
-        if (vips_tiffsave(image, baton->output.c_str(), "strip", !baton->withMetadata,
-          "compression", VIPS_FOREIGN_TIFF_COMPRESSION_JPEG, "Q", baton->quality, NULL)) {
-          return Error(baton, hook);
-        }
-        baton->outputFormat = "tiff";
-      } else {
-        (baton->err).append("Unsupported output " + baton->output);
-        return Error(baton, hook);
-      }
-    }
-    // Clean up any dangling image references
-    g_object_unref(hook);
-    // Clean up libvips' per-request data and threads
-    vips_error_clear();
-    vips_thread_shutdown();
-  }
-
-  void HandleOKCallback () {
-    NanScope();
-
-    Handle<Value> argv[3] = { NanNull(), NanNull(),  NanNull() };
-    if (!baton->err.empty()) {
-      // Error
-      argv[0] = Exception::Error(NanNew<String>(baton->err.data(), baton->err.size()));
-    } else {
-      int width = baton->width;
-      int height = baton->height;
-      if (baton->topOffsetPre != -1 && (baton->width == -1 || baton->height == -1)) {
-        width = baton->widthPre;
-        height = baton->heightPre;
-      }
-      if (baton->topOffsetPost != -1) {
-        width = baton->widthPost;
-        height = baton->heightPost;
-      }
-      // Info Object
-      Local<Object> info = NanNew<Object>();
-      info->Set(NanNew<String>("format"), NanNew<String>(baton->outputFormat));
-      info->Set(NanNew<String>("width"), NanNew<Number>(width));
-      info->Set(NanNew<String>("height"), NanNew<Number>(height));
-
-      if (baton->bufferOutLength > 0) {
-        // Buffer
-        argv[1] = NanNewBufferHandle(static_cast<char*>(baton->bufferOut), baton->bufferOutLength);
-        g_free(baton->bufferOut);
-        argv[2] = info;
-      } else {
-        // File
-        argv[1] = info;
-      }
-    }
-    delete baton;
-
-    // Decrement processing task counter
-    g_atomic_int_dec_and_test(&counterProcess);
-
-    // Return to JavaScript
-    callback->Call(3, argv);
-  }
-
- private:
-  ResizeBaton* baton;
-
-  /*
-    Calculate the angle of rotation and need-to-flip for the output image.
-    In order of priority:
-     1. Use explicitly requested angle (supports 90, 180, 270)
-     2. Use input image EXIF Orientation header - supports mirroring
-     3. Otherwise default to zero, i.e. no rotation
-  */
-  std::tuple<Angle, bool>
-  CalculateRotationAndFlip(int const angle, VipsImage const *input) {
-    Angle rotate = Angle::D0;
-    bool flip = FALSE;
-    if (angle == -1) {
-      switch(ExifOrientation(input)) {
-        case 6: rotate = Angle::D90; break;
-        case 3: rotate = Angle::D180; break;
-        case 8: rotate = Angle::D270; break;
-        case 2: flip = TRUE; break; // flip 1
-        case 7: flip = TRUE; rotate = Angle::D90; break; // flip 6
-        case 4: flip = TRUE; rotate = Angle::D180; break; // flip 3
-        case 5: flip = TRUE; rotate = Angle::D270; break; // flip 8
-      }
-    } else {
-      if (angle == 90) {
-        rotate = Angle::D90;
-      } else if (angle == 180) {
-        rotate = Angle::D180;
-      } else if (angle == 270) {
-        rotate = Angle::D270;
-      }
-    }
-    return std::make_tuple(rotate, flip);
-  }
-
-  /*
-    Calculate the (left, top) coordinates of the output image
-    within the input image, applying the given gravity.
-  */
-  std::tuple<int, int>
-  CalculateCrop(int const inWidth, int const inHeight, int const outWidth, int const outHeight, int const gravity) {
-    int left = 0;
-    int top = 0;
-    switch (gravity) {
-      case 1: // North
-        left = (inWidth - outWidth + 1) / 2;
-        break;
-      case 2: // East
-        left = inWidth - outWidth;
-        top = (inHeight - outHeight + 1) / 2;
-        break;
-      case 3: // South
-        left = (inWidth - outWidth + 1) / 2;
-        top = inHeight - outHeight;
-        break;
-      case 4: // West
-        top = (inHeight - outHeight + 1) / 2;
-        break;
-      default: // Centre
-        left = (inWidth - outWidth + 1) / 2;
-        top = (inHeight - outHeight + 1) / 2;
-    }
-    return std::make_tuple(left, top);
-  }
-
-  /*
-    Copy then clear the error message.
-    Unref all transitional images on the hook.
-    Clear all thread-local data.
-  */
-  void Error(ResizeBaton *baton, VipsObject *hook) {
-    // Get libvips' error message
-    (baton->err).append(vips_error_buffer());
-    // Clean up any dangling image references
-    g_object_unref(hook);
-    // Clean up libvips' per-request data and threads
-    vips_error_clear();
-    vips_thread_shutdown();
-  }
-};
-
-/*
-  resize(options, output, callback)
-*/
-NAN_METHOD(resize) {
-  NanScope();
-
-  // V8 objects are converted to non-V8 types held in the baton struct
-  ResizeBaton *baton = new ResizeBaton;
-  Local<Object> options = args[0]->ToObject();
-
-  // Input filename
-  baton->fileIn = *String::Utf8Value(options->Get(NanNew<String>("fileIn"))->ToString());
-  baton->accessMethod = options->Get(NanNew<String>("sequentialRead"))->BooleanValue() ? VIPS_ACCESS_SEQUENTIAL : VIPS_ACCESS_RANDOM;
-  // Input Buffer object
-  if (options->Get(NanNew<String>("bufferIn"))->IsObject()) {
-    Local<Object> buffer = options->Get(NanNew<String>("bufferIn"))->ToObject();
-    baton->bufferInLength = node::Buffer::Length(buffer);
-    baton->bufferIn = node::Buffer::Data(buffer);
-  }
-  // ICC profile to use when input CMYK image has no embedded profile
-  baton->iccProfileCmyk = *String::Utf8Value(options->Get(NanNew<String>("iccProfileCmyk"))->ToString());
-  // Extract image options
-  baton->topOffsetPre = options->Get(NanNew<String>("topOffsetPre"))->Int32Value();
-  baton->leftOffsetPre = options->Get(NanNew<String>("leftOffsetPre"))->Int32Value();
-  baton->widthPre = options->Get(NanNew<String>("widthPre"))->Int32Value();
-  baton->heightPre = options->Get(NanNew<String>("heightPre"))->Int32Value();
-  baton->topOffsetPost = options->Get(NanNew<String>("topOffsetPost"))->Int32Value();
-  baton->leftOffsetPost = options->Get(NanNew<String>("leftOffsetPost"))->Int32Value();
-  baton->widthPost = options->Get(NanNew<String>("widthPost"))->Int32Value();
-  baton->heightPost = options->Get(NanNew<String>("heightPost"))->Int32Value();
-  // Output image dimensions
-  baton->width = options->Get(NanNew<String>("width"))->Int32Value();
-  baton->height = options->Get(NanNew<String>("height"))->Int32Value();
-  // Canvas option
-  Local<String> canvas = options->Get(NanNew<String>("canvas"))->ToString();
-  if (canvas->Equals(NanNew<String>("c"))) {
-    baton->canvas = Canvas::CROP;
-  } else if (canvas->Equals(NanNew<String>("m"))) {
-    baton->canvas = Canvas::MAX;
-  } else if (canvas->Equals(NanNew<String>("e"))) {
-    baton->canvas = Canvas::EMBED;
-  }
-  // Background colour
-  Local<Array> background = Local<Array>::Cast(options->Get(NanNew<String>("background")));
-  for (int i = 0; i < 4; i++) {
-    baton->background[i] = background->Get(i)->NumberValue();
-  }
-  // Resize options
-  baton->withoutEnlargement = options->Get(NanNew<String>("withoutEnlargement"))->BooleanValue();
-  baton->gravity = options->Get(NanNew<String>("gravity"))->Int32Value();
-  baton->interpolator = *String::Utf8Value(options->Get(NanNew<String>("interpolator"))->ToString());
-  // Operators
-  baton->flatten = options->Get(NanNew<String>("flatten"))->BooleanValue();
-  baton->blurRadius = options->Get(NanNew<String>("blurRadius"))->Int32Value();
-  baton->sharpenRadius = options->Get(NanNew<String>("sharpenRadius"))->Int32Value();
-  baton->sharpenFlat = options->Get(NanNew<String>("sharpenFlat"))->NumberValue();
-  baton->sharpenJagged = options->Get(NanNew<String>("sharpenJagged"))->NumberValue();
-  baton->gamma = options->Get(NanNew<String>("gamma"))->NumberValue();
-  baton->greyscale = options->Get(NanNew<String>("greyscale"))->BooleanValue();
-  baton->angle = options->Get(NanNew<String>("angle"))->Int32Value();
-  baton->flip = options->Get(NanNew<String>("flip"))->BooleanValue();
-  baton->flop = options->Get(NanNew<String>("flop"))->BooleanValue();
-  // Output options
-  baton->progressive = options->Get(NanNew<String>("progressive"))->BooleanValue();
-  baton->quality = options->Get(NanNew<String>("quality"))->Int32Value();
-  baton->compressionLevel = options->Get(NanNew<String>("compressionLevel"))->Int32Value();
-  baton->withoutAdaptiveFiltering = options->Get(NanNew<String>("withoutAdaptiveFiltering"))->BooleanValue();
-  baton->withMetadata = options->Get(NanNew<String>("withMetadata"))->BooleanValue();
-  // Output filename or __format for Buffer
-  baton->output = *String::Utf8Value(options->Get(NanNew<String>("output"))->ToString());
-
-  // Join queue for worker thread
-  NanCallback *callback = new NanCallback(args[1].As<v8::Function>());
-  NanAsyncQueueWorker(new ResizeWorker(callback, baton));
-
-  // Increment queued task counter
-  g_atomic_int_inc(&counterQueue);
-
-  NanReturnUndefined();
-}

src/resize.h

@@ -1,8 +0,0 @@
-#ifndef SHARP_RESIZE_H
-#define SHARP_RESIZE_H
-
-#include "nan.h"
-
-NAN_METHOD(resize);
-
-#endif

src/sharp.cc

@@ -1,39 +1,54 @@
-#include <node.h>
-#include <vips/vips.h>
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
-#include "nan.h"
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
 
 #include "common.h"
 #include "metadata.h"
-#include "resize.h"
+#include "pipeline.h"
 #include "utilities.h"
+#include "stats.h"
 
-using namespace v8;
-
-static void at_exit(void* arg) {
-  NanScope();
-  vips_shutdown();
-}
-
-extern "C" void init(Handle<Object> target) {
-  NanScope();
+NAN_MODULE_INIT(init) {
   vips_init("sharp");
-  node::AtExit(at_exit);
 
-  // Set libvips operation cache limits
-  vips_cache_set_max_mem(100 * 1048576); // 100 MB
-  vips_cache_set_max(500); // 500 operations
-
-  // Notify the V8 garbage collector of max cache size
-  NanAdjustExternalMemory(vips_cache_get_max_mem());
+  g_log_set_handler("VIPS", static_cast<GLogLevelFlags>(G_LOG_LEVEL_WARNING),
+    static_cast<GLogFunc>(sharp::VipsWarningCallback), nullptr);
 
   // Methods available to JavaScript
-  NODE_SET_METHOD(target, "metadata", metadata);
-  NODE_SET_METHOD(target, "resize", resize);
-  NODE_SET_METHOD(target, "cache", cache);
-  NODE_SET_METHOD(target, "concurrency", concurrency);
-  NODE_SET_METHOD(target, "counters", counters);
-  NODE_SET_METHOD(target, "libvipsVersion", libvipsVersion);
+  Nan::Set(target, Nan::New("metadata").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(metadata)).ToLocalChecked());
+  Nan::Set(target, Nan::New("pipeline").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(pipeline)).ToLocalChecked());
+  Nan::Set(target, Nan::New("cache").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(cache)).ToLocalChecked());
+  Nan::Set(target, Nan::New("concurrency").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(concurrency)).ToLocalChecked());
+  Nan::Set(target, Nan::New("counters").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(counters)).ToLocalChecked());
+  Nan::Set(target, Nan::New("simd").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(simd)).ToLocalChecked());
+  Nan::Set(target, Nan::New("libvipsVersion").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(libvipsVersion)).ToLocalChecked());
+  Nan::Set(target, Nan::New("format").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(format)).ToLocalChecked());
+  Nan::Set(target, Nan::New("_maxColourDistance").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(_maxColourDistance)).ToLocalChecked());
+  Nan::Set(target, Nan::New("stats").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(stats)).ToLocalChecked());
 }
 
 NODE_MODULE(sharp, init)

src/stats.cc

@@ -0,0 +1,192 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <numeric>
+#include <vector>
+#include <iostream>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+
+#include "common.h"
+#include "stats.h"
+
+class StatsWorker : public Nan::AsyncWorker {
+ public:
+  StatsWorker(
+    Nan::Callback *callback, StatsBaton *baton, Nan::Callback *debuglog,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist) :
+    Nan::AsyncWorker(callback, "sharp:StatsWorker"),
+    baton(baton), debuglog(debuglog),
+    buffersToPersist(buffersToPersist) {
+    // Protect Buffer objects from GC, keyed on index
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        SaveToPersistent(index, buffer);
+        return index + 1;
+      });
+  }
+  ~StatsWorker() {}
+
+  const int STAT_MIN_INDEX = 0;
+  const int STAT_MAX_INDEX = 1;
+  const int STAT_SUM_INDEX = 2;
+  const int STAT_SQ_SUM_INDEX = 3;
+  const int STAT_MEAN_INDEX = 4;
+  const int STAT_STDEV_INDEX = 5;
+  const int STAT_MINX_INDEX = 6;
+  const int STAT_MINY_INDEX = 7;
+  const int STAT_MAXX_INDEX = 8;
+  const int STAT_MAXY_INDEX = 9;
+
+  void Execute() {
+    // Decrement queued task counter
+    g_atomic_int_dec_and_test(&sharp::counterQueue);
+    using Nan::New;
+    using Nan::Set;
+    using sharp::MaximumImageAlpha;
+
+    vips::VImage image;
+    sharp::ImageType imageType = sharp::ImageType::UNKNOWN;
+
+    try {
+      std::tie(image, imageType) = OpenInput(baton->input, baton->accessMethod);
+    } catch (vips::VError const &err) {
+      (baton->err).append(err.what());
+    }
+    if (imageType != sharp::ImageType::UNKNOWN) {
+      try {
+        vips::VImage stats = image.stats();
+        int const bands = image.bands();
+        for (int b = 1; b <= bands; b++) {
+          ChannelStats cStats(static_cast<int>(stats.getpoint(STAT_MIN_INDEX, b).front()),
+                              static_cast<int>(stats.getpoint(STAT_MAX_INDEX, b).front()),
+                              stats.getpoint(STAT_SUM_INDEX, b).front(), stats.getpoint(STAT_SQ_SUM_INDEX, b).front(),
+                              stats.getpoint(STAT_MEAN_INDEX, b).front(), stats.getpoint(STAT_STDEV_INDEX, b).front(),
+                              static_cast<int>(stats.getpoint(STAT_MINX_INDEX, b).front()),
+                              static_cast<int>(stats.getpoint(STAT_MINY_INDEX, b).front()),
+                              static_cast<int>(stats.getpoint(STAT_MAXX_INDEX, b).front()),
+                              static_cast<int>(stats.getpoint(STAT_MAXY_INDEX, b).front()));
+          baton->channelStats.push_back(cStats);
+        }
+        // Image is not opaque when alpha layer is present and contains a non-mamixa value
+        if (sharp::HasAlpha(image)) {
+          double const minAlpha = static_cast<double>(stats.getpoint(STAT_MIN_INDEX, bands).front());
+          if (minAlpha != MaximumImageAlpha(image.interpretation())) {
+            baton->isOpaque = false;
+          }
+        }
+        // Estimate entropy via histogram of greyscale value frequency
+        baton->entropy = std::abs(image.colourspace(VIPS_INTERPRETATION_B_W)[0].hist_find().hist_entropy());
+      } catch (vips::VError const &err) {
+        (baton->err).append(err.what());
+      }
+    }
+
+    // Clean up
+    vips_error_clear();
+    vips_thread_shutdown();
+  }
+
+  void HandleOKCallback() {
+    using Nan::New;
+    using Nan::Set;
+    Nan::HandleScope();
+
+    v8::Local<v8::Value> argv[2] = { Nan::Null(), Nan::Null() };
+    if (!baton->err.empty()) {
+      argv[0] = Nan::Error(baton->err.data());
+    } else {
+      // Stats Object
+      v8::Local<v8::Object> info = New<v8::Object>();
+      v8::Local<v8::Array> channels = New<v8::Array>();
+
+      std::vector<ChannelStats>::iterator it;
+      int i = 0;
+      for (it=baton->channelStats.begin() ; it < baton->channelStats.end(); it++, i++) {
+        v8::Local<v8::Object> channelStat = New<v8::Object>();
+        Set(channelStat, New("min").ToLocalChecked(), New<v8::Number>(it->min));
+        Set(channelStat, New("max").ToLocalChecked(), New<v8::Number>(it->max));
+        Set(channelStat, New("sum").ToLocalChecked(), New<v8::Number>(it->sum));
+        Set(channelStat, New("squaresSum").ToLocalChecked(), New<v8::Number>(it->squaresSum));
+        Set(channelStat, New("mean").ToLocalChecked(), New<v8::Number>(it->mean));
+        Set(channelStat, New("stdev").ToLocalChecked(), New<v8::Number>(it->stdev));
+        Set(channelStat, New("minX").ToLocalChecked(), New<v8::Number>(it->minX));
+        Set(channelStat, New("minY").ToLocalChecked(), New<v8::Number>(it->minY));
+        Set(channelStat, New("maxX").ToLocalChecked(), New<v8::Number>(it->maxX));
+        Set(channelStat, New("maxY").ToLocalChecked(), New<v8::Number>(it->maxY));
+        channels->Set(i, channelStat);
+      }
+
+      Set(info, New("channels").ToLocalChecked(), channels);
+      Set(info, New("isOpaque").ToLocalChecked(), New<v8::Boolean>(baton->isOpaque));
+      Set(info, New("entropy").ToLocalChecked(), New<v8::Number>(baton->entropy));
+      argv[1] = info;
+    }
+
+    // Dispose of Persistent wrapper around input Buffers so they can be garbage collected
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        GetFromPersistent(index);
+        return index + 1;
+      });
+    delete baton->input;
+    delete baton;
+
+    // Handle warnings
+    std::string warning = sharp::VipsWarningPop();
+    while (!warning.empty()) {
+      v8::Local<v8::Value> message[1] = { New(warning).ToLocalChecked() };
+      debuglog->Call(1, message, async_resource);
+      warning = sharp::VipsWarningPop();
+    }
+
+    // Return to JavaScript
+    callback->Call(2, argv, async_resource);
+  }
+
+ private:
+  StatsBaton* baton;
+  Nan::Callback *debuglog;
+  std::vector<v8::Local<v8::Object>> buffersToPersist;
+};
+
+/*
+  stats(options, callback)
+*/
+NAN_METHOD(stats) {
+  using sharp::AttrTo;
+
+  // Input Buffers must not undergo GC compaction during processing
+  std::vector<v8::Local<v8::Object>> buffersToPersist;
+
+  // V8 objects are converted to non-V8 types held in the baton struct
+  StatsBaton *baton = new StatsBaton;
+  v8::Local<v8::Object> options = info[0].As<v8::Object>();
+
+  // Input
+  baton->input = sharp::CreateInputDescriptor(sharp::AttrAs<v8::Object>(options, "input"), buffersToPersist);
+  baton->accessMethod = AttrTo<bool>(options, "sequentialRead") ? VIPS_ACCESS_SEQUENTIAL : VIPS_ACCESS_RANDOM;
+
+  // Function to notify of libvips warnings
+  Nan::Callback *debuglog = new Nan::Callback(sharp::AttrAs<v8::Function>(options, "debuglog"));
+
+  // Join queue for worker thread
+  Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
+  Nan::AsyncQueueWorker(new StatsWorker(callback, baton, debuglog, buffersToPersist));
+
+  // Increment queued task counter
+  g_atomic_int_inc(&sharp::counterQueue);
+}

src/stats.h

@@ -0,0 +1,67 @@
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_STATS_H_
+#define SRC_STATS_H_
+
+#include <string>
+#include <nan.h>
+
+#include "./common.h"
+
+struct ChannelStats {
+  // stats per channel
+  int min;
+  int max;
+  double sum;
+  double squaresSum;
+  double mean;
+  double stdev;
+  int minX;
+  int minY;
+  int maxX;
+  int maxY;
+
+  ChannelStats():
+    min(0), max(0), sum(0), squaresSum(0), mean(0), stdev(0)
+    , minX(0), minY(0), maxX(0), maxY(0) {}
+
+    ChannelStats(int minVal, int maxVal, double sumVal, double squaresSumVal,
+                  double meanVal, double stdevVal, int minXVal, int minYVal, int maxXVal, int maxYVal):
+    min(minVal), max(maxVal), sum(sumVal), squaresSum(squaresSumVal),
+    mean(meanVal), stdev(stdevVal), minX(minXVal), minY(minYVal), maxX(maxXVal), maxY(maxYVal) {}
+};
+
+struct StatsBaton {
+  // Input
+  sharp::InputDescriptor *input;
+  VipsAccess accessMethod;
+
+  // Output
+  std::vector<ChannelStats> channelStats;
+  bool isOpaque;
+  double entropy;
+
+  std::string err;
+
+  StatsBaton():
+    input(nullptr),
+    isOpaque(true),
+    entropy(0.0)
+    {}
+};
+
+NAN_METHOD(stats);
+
+#endif  // SRC_STATS_H_

src/utilities.cc

@@ -1,75 +1,271 @@
-#include <node.h>
-#include <vips/vips.h>
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
-#include "nan.h"
+#include <cmath>
+#include <string>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+#include <vips/vector.h>
 
 #include "common.h"
+#include "operations.h"
 #include "utilities.h"
 
-using namespace v8;
-using namespace sharp;
+using v8::Boolean;
+using v8::Integer;
+using v8::Local;
+using v8::Number;
+using v8::Object;
+using v8::String;
+
+using Nan::HandleScope;
+using Nan::New;
+using Nan::Set;
+using Nan::ThrowError;
+using Nan::To;
+using Nan::Utf8String;
 
 /*
-  Get and set cache memory and item limits
+  Get and set cache limits
 */
 NAN_METHOD(cache) {
-  NanScope();
+  HandleScope();
 
-  // Set cache memory limit
-  if (args[0]->IsInt32()) {
-    int newMax = args[0]->Int32Value() * 1048576;
-    int oldMax = vips_cache_get_max_mem();
-    vips_cache_set_max_mem(newMax);
-
-    // Notify the V8 garbage collector of delta in max cache size
-    NanAdjustExternalMemory(newMax - oldMax);
+  // Set memory limit
+  if (info[0]->IsInt32()) {
+    vips_cache_set_max_mem(To<int32_t>(info[0]).FromJust() * 1048576);
+  }
+  // Set file limit
+  if (info[1]->IsInt32()) {
+    vips_cache_set_max_files(To<int32_t>(info[1]).FromJust());
+  }
+  // Set items limit
+  if (info[2]->IsInt32()) {
+    vips_cache_set_max(To<int32_t>(info[2]).FromJust());
   }
 
-  // Set cache items limit
-  if (args[1]->IsInt32()) {
-    vips_cache_set_max(args[1]->Int32Value());
-  }
+  // Get memory stats
+  Local<Object> memory = New<Object>();
+  Set(memory, New("current").ToLocalChecked(),
+    New<Integer>(static_cast<int>(round(vips_tracked_get_mem() / 1048576))));
+  Set(memory, New("high").ToLocalChecked(),
+    New<Integer>(static_cast<int>(round(vips_tracked_get_mem_highwater() / 1048576))));
+  Set(memory, New("max").ToLocalChecked(),
+    New<Integer>(static_cast<int>(round(vips_cache_get_max_mem() / 1048576))));
+  // Get file stats
+  Local<Object> files = New<Object>();
+  Set(files, New("current").ToLocalChecked(), New<Integer>(vips_tracked_get_files()));
+  Set(files, New("max").ToLocalChecked(), New<Integer>(vips_cache_get_max_files()));
 
-  // Get cache statistics
-  Local<Object> cache = NanNew<Object>();
-  cache->Set(NanNew<String>("current"), NanNew<Number>(vips_tracked_get_mem() / 1048576));
-  cache->Set(NanNew<String>("high"), NanNew<Number>(vips_tracked_get_mem_highwater() / 1048576));
-  cache->Set(NanNew<String>("memory"), NanNew<Number>(vips_cache_get_max_mem() / 1048576));
-  cache->Set(NanNew<String>("items"), NanNew<Number>(vips_cache_get_max()));
-  NanReturnValue(cache);
+  // Get item stats
+  Local<Object> items = New<Object>();
+  Set(items, New("current").ToLocalChecked(), New<Integer>(vips_cache_get_size()));
+  Set(items, New("max").ToLocalChecked(), New<Integer>(vips_cache_get_max()));
+
+  Local<Object> cache = New<Object>();
+  Set(cache, New("memory").ToLocalChecked(), memory);
+  Set(cache, New("files").ToLocalChecked(), files);
+  Set(cache, New("items").ToLocalChecked(), items);
+  info.GetReturnValue().Set(cache);
 }
 
 /*
   Get and set size of thread pool
 */
 NAN_METHOD(concurrency) {
-  NanScope();
+  HandleScope();
 
   // Set concurrency
-  if (args[0]->IsInt32()) {
-    vips_concurrency_set(args[0]->Int32Value());
+  if (info[0]->IsInt32()) {
+    vips_concurrency_set(To<int32_t>(info[0]).FromJust());
   }
   // Get concurrency
-  NanReturnValue(NanNew<Number>(vips_concurrency_get()));
+  info.GetReturnValue().Set(New<Integer>(vips_concurrency_get()));
 }
 
 /*
   Get internal counters (queued tasks, processing tasks)
 */
 NAN_METHOD(counters) {
-  NanScope();
-  Local<Object> counters = NanNew<Object>();
-  counters->Set(NanNew<String>("queue"), NanNew<Number>(counterQueue));
-  counters->Set(NanNew<String>("process"), NanNew<Number>(counterProcess));
-  NanReturnValue(counters);
+  using sharp::counterProcess;
+  using sharp::counterQueue;
+
+  HandleScope();
+  Local<Object> counters = New<Object>();
+  Set(counters, New("queue").ToLocalChecked(), New<Integer>(counterQueue));
+  Set(counters, New("process").ToLocalChecked(), New<Integer>(counterProcess));
+  info.GetReturnValue().Set(counters);
+}
+
+/*
+  Get and set use of SIMD vector unit instructions
+*/
+NAN_METHOD(simd) {
+  HandleScope();
+
+  // Set state
+  if (info[0]->IsBoolean()) {
+    vips_vector_set_enabled(To<bool>(info[0]).FromJust());
+  }
+  // Get state
+  info.GetReturnValue().Set(New<Boolean>(vips_vector_isenabled()));
 }
 
 /*
   Get libvips version
 */
 NAN_METHOD(libvipsVersion) {
-  NanScope();
+  HandleScope();
   char version[9];
-  snprintf(version, 9, "%d.%d.%d", vips_version(0), vips_version(1), vips_version(2));
-  NanReturnValue(NanNew<String>(version));
+  g_snprintf(version, sizeof(version), "%d.%d.%d", vips_version(0), vips_version(1), vips_version(2));
+  info.GetReturnValue().Set(New(version).ToLocalChecked());
+}
+
+/*
+  Get available input/output file/buffer/stream formats
+*/
+NAN_METHOD(format) {
+  HandleScope();
+
+  // Attribute names
+  Local<String> attrId = New("id").ToLocalChecked();
+  Local<String> attrInput = New("input").ToLocalChecked();
+  Local<String> attrOutput = New("output").ToLocalChecked();
+  Local<String> attrFile = New("file").ToLocalChecked();
+  Local<String> attrBuffer = New("buffer").ToLocalChecked();
+  Local<String> attrStream = New("stream").ToLocalChecked();
+
+  // Which load/save operations are available for each compressed format?
+  Local<Object> format = New<Object>();
+  for (std::string f : {
+    "jpeg", "png", "webp", "tiff", "magick", "openslide", "dz", "ppm", "fits", "gif", "svg", "pdf", "v"
+  }) {
+    // Input
+    Local<Boolean> hasInputFile =
+      New<Boolean>(vips_type_find("VipsOperation", (f + "load").c_str()));
+    Local<Boolean> hasInputBuffer =
+      New<Boolean>(vips_type_find("VipsOperation", (f + "load_buffer").c_str()));
+    Local<Object> input = New<Object>();
+    Set(input, attrFile, hasInputFile);
+    Set(input, attrBuffer, hasInputBuffer);
+    Set(input, attrStream, hasInputBuffer);
+    // Output
+    Local<Boolean> hasOutputFile =
+      New<Boolean>(vips_type_find("VipsOperation", (f + "save").c_str()));
+    Local<Boolean> hasOutputBuffer =
+      New<Boolean>(vips_type_find("VipsOperation", (f + "save_buffer").c_str()));
+    Local<Object> output = New<Object>();
+    Set(output, attrFile, hasOutputFile);
+    Set(output, attrBuffer, hasOutputBuffer);
+    Set(output, attrStream, hasOutputBuffer);
+    // Other attributes
+    Local<Object> container = New<Object>();
+    Local<String> formatId = New(f).ToLocalChecked();
+    Set(container, attrId, formatId);
+    Set(container, attrInput, input);
+    Set(container, attrOutput, output);
+    // Add to set of formats
+    Set(format, formatId, container);
+  }
+
+  // Raw, uncompressed data
+  Local<Object> raw = New<Object>();
+  Local<String> rawId = New("raw").ToLocalChecked();
+  Set(raw, attrId, rawId);
+  Set(format, rawId, raw);
+  Local<Boolean> supported = New<Boolean>(true);
+  Local<Boolean> unsupported = New<Boolean>(false);
+  Local<Object> rawInput = New<Object>();
+  Set(rawInput, attrFile, unsupported);
+  Set(rawInput, attrBuffer, supported);
+  Set(rawInput, attrStream, supported);
+  Set(raw, attrInput, rawInput);
+  Local<Object> rawOutput = New<Object>();
+  Set(rawOutput, attrFile, unsupported);
+  Set(rawOutput, attrBuffer, supported);
+  Set(rawOutput, attrStream, supported);
+  Set(raw, attrOutput, rawOutput);
+
+  info.GetReturnValue().Set(format);
+}
+
+/*
+  Synchronous, internal-only method used by some of the functional tests.
+  Calculates the maximum colour distance using the DE2000 algorithm
+  between two images of the same dimensions and number of channels.
+*/
+NAN_METHOD(_maxColourDistance) {
+  using vips::VImage;
+  using vips::VError;
+  using sharp::DetermineImageType;
+  using sharp::ImageType;
+  using sharp::HasAlpha;
+
+  HandleScope();
+
+  // Open input files
+  VImage image1;
+  ImageType imageType1 = DetermineImageType(*Utf8String(info[0]));
+  if (imageType1 != ImageType::UNKNOWN) {
+    try {
+      image1 = VImage::new_from_file(*Utf8String(info[0]));
+    } catch (...) {
+      return ThrowError("Input file 1 has corrupt header");
+    }
+  } else {
+    return ThrowError("Input file 1 is of an unsupported image format");
+  }
+  VImage image2;
+  ImageType imageType2 = DetermineImageType(*Utf8String(info[1]));
+  if (imageType2 != ImageType::UNKNOWN) {
+    try {
+      image2 = VImage::new_from_file(*Utf8String(info[1]));
+    } catch (...) {
+      return ThrowError("Input file 2 has corrupt header");
+    }
+  } else {
+    return ThrowError("Input file 2 is of an unsupported image format");
+  }
+  // Ensure same number of channels
+  if (image1.bands() != image2.bands()) {
+    return ThrowError("mismatchedBands");
+  }
+  // Ensure same dimensions
+  if (image1.width() != image2.width() || image1.height() != image2.height()) {
+    return ThrowError("mismatchedDimensions");
+  }
+
+  double maxColourDistance;
+  try {
+    // Premultiply and remove alpha
+    if (HasAlpha(image1)) {
+      image1 = image1.premultiply().extract_band(1, VImage::option()->set("n", image1.bands() - 1));
+    }
+    if (HasAlpha(image2)) {
+      image2 = image2.premultiply().extract_band(1, VImage::option()->set("n", image2.bands() - 1));
+    }
+    // Calculate colour distance
+    maxColourDistance = image1.dE00(image2).max();
+  } catch (VError const &err) {
+    return ThrowError(err.what());
+  }
+
+  // Clean up libvips' per-request data and threads
+  vips_error_clear();
+  vips_thread_shutdown();
+
+  info.GetReturnValue().Set(New<Number>(maxColourDistance));
 }

src/utilities.h

@@ -1,11 +1,28 @@
-#ifndef SHARP_UTILITIES_H
-#define SHARP_UTILITIES_H
+// Copyright 2013, 2014, 2015, 2016, 2017, 2018, 2019 Lovell Fuller and contributors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
-#include "nan.h"
+#ifndef SRC_UTILITIES_H_
+#define SRC_UTILITIES_H_
+
+#include <nan.h>
 
 NAN_METHOD(cache);
 NAN_METHOD(concurrency);
 NAN_METHOD(counters);
+NAN_METHOD(simd);
 NAN_METHOD(libvipsVersion);
+NAN_METHOD(format);
+NAN_METHOD(_maxColourDistance);
 
-#endif
+#endif  // SRC_UTILITIES_H_

test/bench/package.json

@@ -8,15 +8,17 @@
     "test": "node perf && node random && node parallel"
   },
   "devDependencies": {
+    "async": "^2.6.1",
+    "benchmark": "^2.1.4",
+    "gm": "^1.23.1",
     "imagemagick": "^0.1.3",
-    "imagemagick-native": "^1.5.0",
-    "gm": "^1.17.0",
-    "async": "^0.9.0",
-    "semver": "^4.1.0",
-    "benchmark": "^1.0.0"
+    "imagemagick-native": "^1.9.3",
+    "jimp": "^0.5.3",
+    "mapnik": "^4.0.1",
+    "semver": "^5.5.1"
   },
-  "license": "Apache 2.0",
+  "license": "Apache-2.0",
   "engines": {
-    "node": ">=0.10"
+    "node": ">=6"
   }
 }

test/bench/parallel.js

@@ -1,41 +1,45 @@
 'use strict';
 
-var assert = require('assert');
-var async = require('async');
+process.env.UV_THREADPOOL_SIZE = 64;
 
-var sharp = require('../../index');
-var fixtures = require('../fixtures');
+const assert = require('assert');
+const async = require('async');
 
-var width = 720;
-var height = 480;
+const sharp = require('../../');
+const fixtures = require('../fixtures');
+
+const width = 720;
+const height = 480;
 
 sharp.concurrency(1);
+sharp.simd(true);
 
-var timer = setInterval(function() {
+const timer = setInterval(function () {
   console.dir(sharp.counters());
 }, 100);
 
-async.mapSeries([1, 1, 2, 4, 8, 16, 32, 64, 128], function(parallelism, next) {
-  var start = new Date().getTime();
+async.mapSeries([1, 1, 2, 4, 8, 16, 32, 64], function (parallelism, next) {
+  const start = new Date().getTime();
   async.times(parallelism,
-    function(id, callback) {
-      /*jslint unused: false */
-      sharp(fixtures.inputJpg).resize(width, height).toBuffer(function(err, buffer) {
+    function (id, callback) {
+      /* jslint unused: false */
+      sharp(fixtures.inputJpg).resize(width, height).toBuffer(function (err, buffer) {
         buffer = null;
         callback(err, new Date().getTime() - start);
       });
     },
-    function(err, ids) {
+    function (err, ids) {
       assert(!err);
       assert(ids.length === parallelism);
-      var mean = ids.reduce(function(a, b) {
+      ids.sort();
+      const mean = ids.reduce(function (a, b) {
         return a + b;
       }) / ids.length;
       console.log(parallelism + ' parallel calls: fastest=' + ids[0] + 'ms slowest=' + ids[ids.length - 1] + 'ms mean=' + mean + 'ms');
       next();
     }
   );
-}, function() {
+}, function () {
   clearInterval(timer);
   console.dir(sharp.counters());
 });

test/bench/random.js

@@ -1,30 +1,35 @@
 'use strict';
 
-var imagemagick = require('imagemagick');
-var gm = require('gm');
-var assert = require('assert');
-var Benchmark = require('benchmark');
+const imagemagick = require('imagemagick');
+const gm = require('gm');
+const assert = require('assert');
+const Benchmark = require('benchmark');
 
-var sharp = require('../../index');
-var fixtures = require('../fixtures');
+const sharp = require('../../');
+const fixtures = require('../fixtures');
 
-var min = 320;
-var max = 960;
+sharp.cache(false);
+sharp.simd(true);
 
-var randomDimension = function() {
-  return Math.random() * (max - min) + min;
+const min = 320;
+const max = 960;
+
+const randomDimension = function () {
+  return Math.ceil((Math.random() * (max - min)) + min);
 };
 
 new Benchmark.Suite('random').add('imagemagick', {
   defer: true,
-  fn: function(deferred) {
+  fn: function (deferred) {
     imagemagick.resize({
       srcPath: fixtures.inputJpg,
       dstPath: fixtures.outputJpg,
       quality: 0.8,
       width: randomDimension(),
-      height: randomDimension()
-    }, function(err) {
+      height: randomDimension(),
+      format: 'jpg',
+      filter: 'Lanczos'
+    }, function (err) {
       if (err) {
         throw err;
       } else {
@@ -34,32 +39,37 @@ new Benchmark.Suite('random').add('imagemagick', {
   }
 }).add('gm', {
   defer: true,
-  fn: function(deferred) {
-    gm(fixtures.inputJpg).resize(randomDimension(), randomDimension()).quality(80).toBuffer(function (err, buffer) {
-      if (err) {
-        throw err;
-      } else {
-        assert.notStrictEqual(null, buffer);
-        deferred.resolve();
-      }
-    });
+  fn: function (deferred) {
+    gm(fixtures.inputJpg)
+      .resize(randomDimension(), randomDimension())
+      .filter('Lanczos')
+      .quality(80)
+      .toBuffer(function (err, buffer) {
+        if (err) {
+          throw err;
+        } else {
+          assert.notStrictEqual(null, buffer);
+          deferred.resolve();
+        }
+      });
   }
 }).add('sharp', {
   defer: true,
-  fn: function(deferred) {
-    sharp(fixtures.inputJpg).resize(randomDimension(), randomDimension()).toBuffer(function(err, buffer) {
-      if (err) {
-        throw err;
-      } else {
-        assert.notStrictEqual(null, buffer);
-        deferred.resolve();
-      }
-    });
+  fn: function (deferred) {
+    sharp(fixtures.inputJpg)
+      .resize(randomDimension(), randomDimension())
+      .toBuffer(function (err, buffer) {
+        if (err) {
+          throw err;
+        } else {
+          assert.notStrictEqual(null, buffer);
+          deferred.resolve();
+        }
+      });
   }
-}).on('cycle', function(event) {
+}).on('cycle', function (event) {
   console.log(String(event.target));
-}).on('complete', function() {
-  var winner = this.filter('fastest').pluck('name');
+}).on('complete', function () {
+  const winner = this.filter('fastest').map('name');
   assert.strictEqual('sharp', String(winner), 'sharp was slower than ' + winner);
-  console.dir(sharp.cache());
 }).run();

test/coverage/report.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+CPPFLAGS="--coverage" LDFLAGS="--coverage" npm rebuild
+npm test
+geninfo --no-external --base-directory src --output-file coverage/sharp.info build/Release/obj.target/sharp/src
+genhtml --title sharp --demangle-cpp --output-directory coverage/sharp coverage/*.info