Release v0.17.1

Dependency version bumps and doc refresh

.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

.gitignore

@@ -1,15 +1,16 @@
-lib-cov
-*.seed
-*.log
-*.csv
-*.dat
-*.out
-*.pid
-*.gz
-
-pids
-logs
-results
 build
 node_modules
-tests/fixtures/output.*
+coverage
+test/bench/node_modules
+test/fixtures/output*
+test/leak/libvips.supp
+test/saliency/report.json
+test/saliency/Image*
+test/saliency/[Uu]serData*
+!test/saliency/userData.js
+vendor
+packaging/libvips*
+packaging/*.log
+!packaging/build
+.DS_Store
+.nyc_output

.npmignore

@@ -1,18 +1,14 @@
-lib-cov
-*.seed
-*.log
-*.csv
-*.dat
-*.out
-*.pid
-*.gz
-
-pids
-logs
-results
 build
 node_modules
-
+coverage
+.editorconfig
 .gitignore
-tests
-.travis.yml
+test
+.travis.yml
+appveyor.yml
+circle.yml
+mkdocs.yml
+vendor
+packaging
+preinstall.sh
+.nyc_output

.travis.yml

@@ -1,17 +1,21 @@
 language: node_js
 node_js:
-  - "0.10"
-  - "0.11"
+  - "4"
+  - "6"
+  - "7"
+os:
+  - linux
+  - osx
+sudo: false
+addons:
+  apt:
+    sources:
+    - ubuntu-toolchain-r-test
+    packages:
+    - g++-4.8
+osx_image: xcode8
 before_install:
-  - sudo add-apt-repository ppa:lyrasis/precise-backports -y
-  - sudo apt-get update -qq
-  - sudo apt-get install -qq automake gobject-introspection gtk-doc-tools libglib2.0-dev libjpeg-turbo8-dev libpng12-dev libwebp-dev libtiff4-dev libexif-dev libxml2-dev swig graphicsmagick libmagick++-dev
-  - git clone https://github.com/jcupitt/libvips.git
-  - cd libvips
-  - git checkout 7.38
-  - ./bootstrap.sh
-  - ./configure --enable-debug=no --enable-cxx=yes --without-orc --without-python --without-fftw
-  - make
-  - sudo make install
-  - sudo ldconfig
-  - cd $TRAVIS_BUILD_DIR
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export CXX=g++-4.8; fi
+after_success:
+  - npm install coveralls
+  - cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js

CONTRIBUTING.md

@@ -0,0 +1,114 @@
+# 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](http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/ch03.html) 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 |
+| ------: | :--------- |
+| v0.17.0 | quill      |
+| v0.18.0 | ridge      |
+| v0.19.0 | suit       |
+
+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
+```
+
+The `types.d.ts` TypeScript declaration can be generated by running:
+```sh
+npm run types
+```
+
+Please include documentation and TypeScript declaration 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
+```
+
+### Packaging tests
+
+Tests the installation on a number of Linux-based operating systems.
+Requires docker.
+
+```sh
+npm run test-packaging
+```
+
+## 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

@@ -1,423 +1,85 @@
 # 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)
-* [Licence](https://github.com/lovell/sharp#licence)
-
-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) v7.38.5+
-
-_libvips_ can take advantage of [liborc](http://code.entropywave.com/orc/) if present. Warning: versions of _liborc_ prior to 0.4.19 suffer [memory leaks](https://github.com/lovell/sharp/issues/21#issuecomment-42367306) and version 0.4.19 suffers [buffer overflows](https://github.com/lovell/sharp/issues/21#issuecomment-44813498).
-
-### Install libvips on Mac OS
-
-	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 Ubuntu Linux
-
-#### Ubuntu 14.x
-
-	sudo apt-get install libvips-dev
-
-#### Ubuntu 13.x
-
-Compiling from source is recommended:
-
-	sudo apt-get install automake build-essential git gobject-introspection gtk-doc-tools libglib2.0-dev libjpeg-turbo8-dev libpng12-dev libwebp-dev libtiff5-dev libexif-dev libxml2-dev swig
-	git clone https://github.com/jcupitt/libvips.git
-	cd libvips
-	git checkout 7.38
-	./bootstrap.sh
-	./configure --enable-debug=no --enable-cxx=yes --without-python --without-orc --without-fftw
-	make
-	sudo make install
-	sudo ldconfig
-
-#### Ubuntu 12.x
-
-Requires `libtiff4-dev` instead of `libtiff5-dev` and has [a bug](https://bugs.launchpad.net/ubuntu/+source/libwebp/+bug/1108731) in the libwebp package. Work around these problems by running these commands first:
-
-	sudo add-apt-repository ppa:lyrasis/precise-backports
-	sudo apt-get update
-	sudo apt-get install libtiff4-dev
-
-Then follow Ubuntu 13.x instructions.
-
-### 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.
-
-## 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.
+
+OS X, Windows (x64), Linux (x64, ARM) systems do not require
+the installation of any external 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
-```
-
-```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
-  });
-});
-```
-
-```javascript
-var pipeline = sharp()
-  .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)
-  .sharpen()
-  .quality(90)
-  .webp()
-  .toBuffer()
-  .then(function(outputBuffer) {
-    // outputBuffer contains 300px wide, upside down, sharpened,
-    // 90% quality WebP image data
-  });
-```
-
-```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
+import sharp from 'sharp';
 ```
 
 ```javascript
 sharp(inputBuffer)
-  .resize(200, 300)
-  .interpolateWith(sharp.interpolator.nohalo)
-  .embedWhite()
-  .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
-  });
+  .resize(320, 240)
+  .toFile('output.webp', (err, info) => ... );
 ```
 
 ```javascript
-sharp('input.gif').resize(200, 300).embedBlack().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 black canvas, of input.gif
-});
+sharp('input.jpg')
+  .rotate()
+  .resize(200)
+  .toBuffer()
+  .then( data => ... )
+  .catch( err => ... );
 ```
 
 ```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
-});
+const roundedCorners = new Buffer(
+  '<svg><rect x="0" y="0" width="200" height="200" rx="50" ry="50"/></svg>'
+);
+
+const roundedCornerResizer =
+  sharp()
+    .resize(200, 200)
+    .overlayWith(roundedCorners, { cutout: true })
+    .png();
+
+readableStream
+  .pipe(roundedCornerResizer)
+  .pipe(writableStream);
 ```
 
-## API
+[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.png?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
 
-### Input methods
+### Documentation
 
-#### sharp([input])
+Visit [sharp.dimens.io](http://sharp.dimens.io/) for complete
+[installation instructions](http://sharp.dimens.io/page/install),
+[API documentation](http://sharp.dimens.io/page/api),
+[benchmark tests](http://sharp.dimens.io/page/performance) and
+[changelog](http://sharp.dimens.io/page/changelog).
 
-Constructor to which further methods are chained. `input`, if present, can be one of:
+### Contributing
 
-* Buffer containing JPEG, PNG or WebP image data, or
-* String containing the filename of an image, with most major formats supported.
+A [guide for contributors](https://github.com/lovell/sharp/blob/master/CONTRIBUTING.md)
+covers reporting bugs, requesting features and submitting code changes.
 
-The object returned implements the [stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
+### Licence
 
-JPEG, PNG or WebP 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#L502)
-* `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
-* `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.
-
-#### 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`.
-
-#### embedWhite()
-
-Embed the resized image on a white background of the exact size specified.
-
-#### embedBlack()
-
-Embed the resized image on a black background of the exact size specified.
-
-#### 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 currently unsupported.
-
-#### 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".
-
-#### sharpen()
-
-Perform a mild sharpen of the resultant image. This typically reduces performance by 30%.
-
-#### 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:
-
-* `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), the default (and fastest) 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" when enlarging 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.
-
-### Output options
-
-#### 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.
-
-#### 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.
-
-#### 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 -1 and 9.
-
-#### jpeg()
-
-Use JPEG format for the output image.
-
-#### png()
-
-Use PNG format for the output image.
-
-#### webp()
-
-Use WebP format for the output image.
-
-### 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 final resized image dimensions in its `width` and `height` properties
-
-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 resultant image data
-* `info` contains the final resized image dimensions in its `width` and `height` properties
-
-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.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
-
-[![Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
-
-	npm test
-
-Running the tests requires both ImageMagick and GraphicsMagick plus one of either libmagick++-dev or libgraphicsmagick++.
-
-	brew install imagemagick
-	brew install graphicsmagick
-
-	sudo apt-get install imagemagick graphicsmagick libmagick++-dev
-
-## Performance
-
-### Test environment
-
-* Intel Xeon [L5520](http://ark.intel.com/products/40201/Intel-Xeon-Processor-L5520-8M-Cache-2_26-GHz-5_86-GTs-Intel-QPI) 2.27GHz 8MB cache
-* Ubuntu 13.10
-* libvips 7.38.5
-
-### The contenders
-
-* [imagemagick-native](https://github.com/mash/node-imagemagick-native) - Supports Buffers only and blocks main V8 thread whilst processing.
-* [imagemagick](https://github.com/rsms/node-imagemagick) - Supports filesystem only and "has been unmaintained for a long time".
-* [gm](https://github.com/aheckmann/gm) - Fully featured wrapper around GraphicsMagick.
-* sharp - 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 |    0.97 |        1 |
-| imagemagick           | file   | file   |    2.49 |      2.6 |
-| gm                    | buffer | file   |    3.72 |      3.8 |
-| gm                    | buffer | buffer |    3.80 |      3.9 |
-| gm                    | file   | file   |    3.67 |      3.8 |
-| gm                    | file   | buffer |    3.67 |      3.8 |
-| sharp                 | buffer | file   |   13.62 |     14.0 |
-| sharp                 | buffer | buffer |   12.43 |     12.8 |
-| sharp                 | file   | file   |   13.02 |     13.4 |
-| sharp                 | file   | buffer |   11.15 |     11.5 |
-| sharp +sharpen        | file   | buffer |   10.26 |     10.6 |
-| sharp +progressive    | file   | buffer |    9.44 |      9.7 |
-| sharp +sequentialRead | file   | buffer |   11.94 |     12.3 |
-
-You can expect much greater performance with caching enabled (default) and using 16+ core machines.
-
-## Licence
-
-Copyright 2013, 2014 Lovell Fuller, Pierre Inglebert, Jonathan Ong and Chanon Sajjamanochai
+Copyright 2013, 2014, 2015, 2016, 2017 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
+[http://www.apache.org/licenses/LICENSE-2.0](http://www.apache.org/licenses/LICENSE-2.0.html)
 
 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 +1,15 @@
+os: Visual Studio 2015
+version: "{build}"
+build: off
+platform: x64
+environment:
+  matrix:
+  - nodejs_version: "4"
+  - nodejs_version: "6"
+  - nodejs_version: "7"
+install:
+  - ps: Install-Product node $env:nodejs_version x64
+  - npm install -g npm@latest
+  - npm install
+test_script:
+  - npm test

binding.gyp

@@ -1,21 +1,278 @@
 {
   'targets': [{
+    'target_name': 'libvips-cpp',
+    'conditions': [
+      ['OS == "win"', {
+        # Build libvips C++ binding for Windows due to MSVC std library ABI changes
+        'type': 'shared_library',
+        'variables': {
+          'download_vips': '<!(node -e "require(\'./binding\').download_vips()")'
+        },
+        '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/sharp.cc'],
+    'dependencies': [
+      'libvips-cpp'
+    ],
+    # Nested variables "pattern" borrowed from http://src.chromium.org/viewvc/chrome/trunk/src/build/common.gypi
     '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'
+      'variables': {
+        'variables': {
+          'conditions': [
+            ['OS != "win"', {
+              # Build the PKG_CONFIG_PATH environment variable with all possible combinations
+              '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'
+            }, {
+              'pkg_config_path': ''
+            }]
+          ],
+        },
+        'conditions': [
+          ['OS != "win"', {
+            # Which version, if any, of libvips is available globally via pkg-config?
+            'global_vips_version': '<!(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --modversion vips-cpp 2>/dev/null || true)'
+          }, {
+            'global_vips_version': ''
+          }]
+        ],
+        'pkg_config_path%': '<(pkg_config_path)'
+      },
+      'pkg_config_path%': '<(pkg_config_path)',
+      'runtime_link%': 'shared',
+      'conditions': [
+        ['OS != "win"', {
+          # Does the globally available version of libvips, if any, meet the minimum version requirement?
+          'use_global_vips': '<!(GLOBAL_VIPS_VERSION="<(global_vips_version)" node -e "require(\'./binding\').use_global_vips()")'
+        }, {
+          'use_global_vips': ''
+        }]
+      ]
     },
-    'libraries': [
-      '<!(PKG_CONFIG_PATH="<(PKG_CONFIG_PATH)" pkg-config --libs vips)'
+    'sources': [
+      'src/common.cc',
+      'src/metadata.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\')")'
     ],
-    'cflags': ['-fexceptions', '-Wall', '-O3'],
-    'cflags_cc': ['-std=c++0x', '-fexceptions', '-Wall', '-O3'],
+    'conditions': [
+      ['use_global_vips == "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)'
+            ]
+          }]
+        ]
+      }, {
+        # Attempt to download pre-built libvips and install 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"', {
+            'variables': {
+              'download_vips': '<!(node -e "require(\'./binding\').download_vips()")'
+            },
+            '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"', {
+            'variables': {
+              'download_vips': '<!(LDD_VERSION="<!(ldd --version 2>&1 || true)" node -e "require(\'./binding\').download_vips()")'
+            },
+            '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/libffi.so',
+              '../vendor/lib/libfontconfig.so',
+              '../vendor/lib/libfreetype.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/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',
+      '-Wall',
+      '-O3'
+    ],
     'xcode_settings': {
-      'OTHER_CFLAGS': ['-std=c++11', '-fexceptions', '-Wall', '-O3']
-    }
+      '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': [
+        '-fexceptions',
+        '-Wall',
+        '-O3'
+      ]
+    },
+    'configurations': {
+      'Release': {
+        'msvs_settings': {
+          'VCCLCompilerTool': {
+            'ExceptionHandling': 1
+          }
+        },
+        'msvs_disabled_warnings': [
+          4275
+        ]
+      }
+    },
+  }, {
+    'target_name': 'win_copy_dlls',
+    'type': 'none',
+    'dependencies': [
+      'sharp'
+    ],
+    'conditions': [
+      ['OS == "win"', {
+        # Windows lacks support for rpath
+        'copies': [{
+          'destination': 'build/Release',
+          'files': [
+            'vendor/lib/GNU.Gettext.dll',
+            'vendor/lib/libasprintf-0.dll',
+            'vendor/lib/libcairo-2.dll',
+            'vendor/lib/libcairo-gobject-2.dll',
+            'vendor/lib/libcairo-script-interpreter-2.dll',
+            'vendor/lib/libcharset-1.dll',
+            'vendor/lib/libcroco-0.6-3.dll',
+            'vendor/lib/libexif-12.dll',
+            'vendor/lib/libexpat-1.dll',
+            'vendor/lib/libffi-6.dll',
+            'vendor/lib/libfftw3-3.dll',
+            'vendor/lib/libfontconfig-1.dll',
+            'vendor/lib/libfreetype-6.dll',
+            'vendor/lib/libgcc_s_seh-1.dll',
+            'vendor/lib/libgdk_pixbuf-2.0-0.dll',
+            'vendor/lib/libgif-7.dll',
+            'vendor/lib/libgio-2.0-0.dll',
+            'vendor/lib/libglib-2.0-0.dll',
+            'vendor/lib/libgmodule-2.0-0.dll',
+            'vendor/lib/libgobject-2.0-0.dll',
+            'vendor/lib/libgsf-1-114.dll',
+            'vendor/lib/libgthread-2.0-0.dll',
+            'vendor/lib/libiconv-2.dll',
+            'vendor/lib/libintl-8.dll',
+            'vendor/lib/libjpeg-62.dll',
+            'vendor/lib/liblcms2-2.dll',
+            'vendor/lib/libpango-1.0-0.dll',
+            'vendor/lib/libpangocairo-1.0-0.dll',
+            'vendor/lib/libpangowin32-1.0-0.dll',
+            'vendor/lib/libpixman-1-0.dll',
+            'vendor/lib/libpng16-16.dll',
+            'vendor/lib/libquadmath-0.dll',
+            'vendor/lib/librsvg-2-2.dll',
+            'vendor/lib/libssp-0.dll',
+            'vendor/lib/libstdc++-6.dll',
+            'vendor/lib/libtiff-5.dll',
+            'vendor/lib/libvips-42.dll',
+            'vendor/lib/libwebp-6.dll',
+            'vendor/lib/libxml2-2.dll',
+            'vendor/lib/zlib1.dll'
+          ]
+        }]
+      }]
+    ]
   }]
 }

binding.js

@@ -0,0 +1,129 @@
+'use strict';
+
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const zlib = require('zlib');
+
+const caw = require('caw');
+const got = require('got');
+const semver = require('semver');
+const tar = require('tar');
+
+const distBaseUrl = 'https://dl.bintray.com/lovell/sharp/';
+
+// Use NPM-provided environment variable where available, falling back to require-based method for Electron
+const minimumLibvipsVersion = process.env.npm_package_config_libvips || require('./package.json').config.libvips;
+
+const platform = process.env.npm_config_platform || process.platform;
+
+const arch = process.env.npm_config_arch || process.arch;
+
+// -- Helpers
+
+// Does this file exist?
+const isFile = function (file) {
+  try {
+    return fs.statSync(file).isFile();
+  } catch (err) {}
+};
+
+const unpack = function (tarPath, done) {
+  const extractor = tar.Extract({ path: path.join(__dirname, 'vendor') });
+  if (done) {
+    extractor.on('end', done);
+  }
+  extractor.on('error', error);
+  fs.createReadStream(tarPath)
+    .on('error', error)
+    .pipe(zlib.Unzip())
+    .pipe(extractor);
+};
+
+const platformId = function () {
+  const platformId = [platform];
+  if (arch === 'arm' || arch === 'armhf' || arch === 'arch64') {
+    const armVersion = (arch === 'arch64') ? '8' : process.env.npm_config_armv || process.config.variables.arm_version || '6';
+    platformId.push('armv' + armVersion);
+  } else {
+    platformId.push(arch);
+  }
+  return platformId.join('-');
+};
+
+// Error
+const error = function (msg) {
+  if (msg instanceof Error) {
+    msg = msg.message;
+  }
+  process.stderr.write('ERROR: ' + msg + '\n');
+  process.exit(1);
+};
+
+// -- Binary downloaders
+
+module.exports.download_vips = function () {
+  // Has vips been installed locally?
+  const vipsHeaderPath = path.join(__dirname, 'vendor', 'include', 'vips', 'vips.h');
+  if (!isFile(vipsHeaderPath)) {
+    // Ensure Intel 64-bit or ARM
+    if (arch === 'ia32') {
+      error('Intel Architecture 32-bit systems require manual installation - please see http://sharp.dimens.io/en/stable/install/');
+    }
+    // Ensure glibc >= 2.15
+    const lddVersion = process.env.LDD_VERSION;
+    if (lddVersion) {
+      if (/(glibc|gnu libc)/i.test(lddVersion)) {
+        const glibcVersion = lddVersion ? lddVersion.split(/\n/)[0].split(' ').slice(-1)[0].trim() : '';
+        if (glibcVersion && semver.lt(glibcVersion + '.0', '2.13.0')) {
+          error('glibc version ' + glibcVersion + ' requires manual installation - please see http://sharp.dimens.io/en/stable/install/');
+        }
+      } else {
+        error(lddVersion.split(/\n/)[0] + ' requires manual installation - please see http://sharp.dimens.io/en/stable/install/');
+      }
+    }
+    // Arch/platform-specific .tar.gz
+    const tarFilename = ['libvips', minimumLibvipsVersion, platformId()].join('-') + '.tar.gz';
+    const tarPathLocal = path.join(__dirname, 'packaging', tarFilename);
+    if (isFile(tarPathLocal)) {
+      unpack(tarPathLocal);
+    } else {
+      // Download to per-process temporary file
+      const tarPathTemp = path.join(os.tmpdir(), process.pid + '-' + tarFilename);
+      const tmpFile = fs.createWriteStream(tarPathTemp).on('finish', function () {
+        unpack(tarPathTemp, function () {
+          // Attempt to remove temporary file
+          try {
+            fs.unlinkSync(tarPathTemp);
+          } catch (err) {}
+        });
+      });
+      const gotOpt = {
+        agent: caw(null, {
+          protocol: 'https'
+        })
+      };
+      const url = distBaseUrl + tarFilename;
+      got.stream(url, gotOpt).on('response', function (response) {
+        if (response.statusCode !== 200) {
+          error(url + ' status code ' + response.statusCode);
+        }
+      }).on('error', function (err) {
+        error('Download of ' + url + ' failed: ' + err.message);
+      }).pipe(tmpFile);
+    }
+  }
+};
+
+module.exports.use_global_vips = function () {
+  const globalVipsVersion = process.env.GLOBAL_VIPS_VERSION;
+  if (globalVipsVersion) {
+    const useGlobalVips = semver.gte(
+      globalVipsVersion,
+      minimumLibvipsVersion
+    );
+    process.stdout.write(useGlobalVips ? 'true' : 'false');
+  } else {
+    process.stdout.write('false');
+  }
+};

circle.yml

@@ -0,0 +1,8 @@
+machine:
+  node:
+    version: v4.6.1
+  services:
+    - docker
+test:
+  override:
+    - ./packaging/test-linux-x64.sh

docs/api-channel.md

@@ -0,0 +1,77 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [extractChannel](#extractchannel)
+-   [joinChannel](#joinchannel)
+-   [bandbool](#bandbool)
+
+## extractChannel
+
+Extract a single channel from a multi-channel image.
+
+**Parameters**
+
+-   `channel` **([Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number) \| [String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String))** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)&lt;([String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) \| [Buffer](https://nodejs.org/api/buffer.html))> | [String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) \| [Buffer](https://nodejs.org/api/buffer.html))** one or more images (file paths, Buffers).
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** image options, see `sharp()` constructor.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 

docs/api-colour.md

@@ -0,0 +1,79 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [background](#background)
+-   [greyscale](#greyscale)
+-   [grayscale](#grayscale)
+-   [toColourspace](#tocolourspace)
+-   [toColorspace](#tocolorspace)
+
+## background
+
+Set the background for the `embed`, `flatten` and `extend` operations.
+The default background is `{r: 0, g: 0, b: 0, alpha: 1}`, black without transparency.
+
+Delegates to the _color_ module, which can throw an Error
+but is liberal in what it accepts, clipping values to sensible min/max.
+The alpha value is a float between `0` (transparent) and `1` (opaque).
+
+**Parameters**
+
+-   `rgba` **([String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) \| [Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object))** parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## grayscale
+
+Alternative spelling of `greyscale`.
+
+**Parameters**
+
+-   `grayscale` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## toColorspace
+
+Alternative spelling of `toColourspace`.
+
+**Parameters**
+
+-   `colorspace` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** output colorspace.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 

docs/api-composite.md

@@ -0,0 +1,51 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [overlayWith](#overlaywith)
+
+## overlayWith
+
+Overlay (composite) an image over the processed (resized, extracted etc.) image.
+
+The overlay image must be the same size or smaller than the processed image.
+If both `top` and `left` options are provided, they take precedence over `gravity`.
+
+**Parameters**
+
+-   `overlay` **([Buffer](https://nodejs.org/api/buffer.html) \| [String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String))** Buffer containing image data or String containing the path to an image file.
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `options.gravity` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** gravity at which to place the overlay. (optional, default `'centre'`)
+    -   `options.top` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the pixel offset from the top edge.
+    -   `options.left` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the pixel offset from the left edge.
+    -   `options.tile` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** set to true to repeat the overlay image across the entire image with the given `gravity`. (optional, default `false`)
+    -   `options.cutout` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** set to true to apply only the alpha channel of the overlay image to the input image, giving the appearance of one image being cut out of another. (optional, default `false`)
+    -   `options.raw` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** describes overlay when using raw pixel data.
+        -   `options.raw.width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.channels` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+
+**Examples**
+
+```javascript
+sharp('input.png')
+  .rotate(180)
+  .resize(300)
+  .flatten()
+  .background('#ff6600')
+  .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
+  .sharpen()
+  .withMetadata()
+  .quality(90)
+  .webp()
+  .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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 

docs/api-constructor.md

@@ -0,0 +1,88 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [Sharp](#sharp)
+    -   [format](#format)
+    -   [versions](#versions)
+-   [queue](#queue)
+
+## Sharp
+
+**Parameters**
+
+-   `input` **([Buffer](https://nodejs.org/api/buffer.html) \| [String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String))?** 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 null or undefined.
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** if present, is an Object with optional attributes.
+    -   `options.density` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** integral number representing the DPI for vector images. (optional, default `72`)
+    -   `options.raw` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** describes raw pixel image data. See `raw()` for pixel ordering.
+        -   `options.raw.width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.channels` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+
+**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);
+```
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **[Sharp](#sharp)** 
+
+### format
+
+An Object containing nested boolean values representing the available input and output formats/methods.
+
+**Examples**
+
+```javascript
+console.log(sharp.format());
+```
+
+Returns **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+
+### 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)');
+});
+```

docs/api-input.md

@@ -0,0 +1,93 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [clone](#clone)
+-   [metadata](#metadata)
+-   [limitInputPixels](#limitinputpixels)
+-   [sequentialRead](#sequentialread)
+
+## 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 image metadata without decoding any compressed image data.
+A Promises/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`
+-   `width`: Number of pixels wide
+-   `height`: Number of pixels high
+-   `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+-   `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+-   `density`: Number of pixels per inch (DPI), if present
+-   `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
+
+**Parameters**
+
+-   `callback` **[Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function)?** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise)&lt;[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)> | Sharp)** 
+
+## limitInputPixels
+
+Do not process input images where the number of pixels (width _ height) exceeds this limit.
+Assumes image dimensions contained in the input metadata can be trusted.
+The default limit is 268402689 (0x3FFF _ 0x3FFF) pixels.
+
+**Parameters**
+
+-   `limit` **([Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number) \| [Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean))** an integral Number of pixels, zero or false to remove limit, true to use default limit.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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.
+
+**Parameters**
+
+-   `sequentialRead` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 

docs/api-operation.md

@@ -0,0 +1,320 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [rotate](#rotate)
+-   [extract](#extract)
+-   [flip](#flip)
+-   [flop](#flop)
+-   [sharpen](#sharpen)
+-   [blur](#blur)
+-   [extend](#extend)
+-   [flatten](#flatten)
+-   [trim](#trim)
+-   [gamma](#gamma)
+-   [negate](#negate)
+-   [normalise](#normalise)
+-   [normalize](#normalize)
+-   [convolve](#convolve)
+-   [threshold](#threshold)
+-   [boolean](#boolean)
+
+## rotate
+
+Rotate the output image by either an explicit angle
+or auto-orient based on the EXIF `Orientation` tag.
+
+Use this method without angle to determine the angle from 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 0, 90, 180 or 270. (optional, default `auto`)
+
+**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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+    -   `options.left` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** zero-indexed offset from left edge
+    -   `options.top` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** zero-indexed offset from top edge
+    -   `options.width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** dimension of extracted image
+    -   `options.height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+-   `flat` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the level of sharpening to apply to "flat" areas. (optional, default `1.0`)
+-   `jagged` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the level of sharpening to apply to "jagged" areas. (optional, default `2.0`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## extend
+
+Extends/pads the edges of the image with the colour provided to the `background` method.
+This operation will always occur after resizing and extraction, if any.
+
+**Parameters**
+
+-   `extend` **([Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number) \| [Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object))** single pixel count to add to all edges or an Object with per-edge counts
+    -   `extend.top` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+    -   `extend.left` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+    -   `extend.bottom` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+    -   `extend.right` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+
+**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)
+  .background({r: 0, g: 0, b: 0, alpha: 0})
+  .extend({top: 10, bottom: 20, left: 10, right: 10})
+  ...
+```
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## flatten
+
+Merge alpha transparency channel, if any, with `background`.
+
+**Parameters**
+
+-   `flatten` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## trim
+
+Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel.
+
+**Parameters**
+
+-   `tolerance` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** value between 1 and 99 representing the percentage similarity. (optional, default `10`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+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.
+
+**Parameters**
+
+-   `gamma` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** value between 1.0 and 3.0. (optional, default `2.2`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## negate
+
+Produce the "negative" of the image.
+
+**Parameters**
+
+-   `negate` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalise
+
+Enhance output image contrast by stretching its luminance to cover the full dynamic range.
+
+**Parameters**
+
+-   `normalise` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalize
+
+Alternative spelling of normalise.
+
+**Parameters**
+
+-   `normalize` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## convolve
+
+Convolve the image with the specified kernel.
+
+**Parameters**
+
+-   `kernel` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+    -   `kernel.width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** width of the kernel in pixels.
+    -   `kernel.height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** width of the kernel in pixels.
+    -   `kernel.kernel` **[Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)&lt;[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)>** Array of length `width*height` containing the kernel values.
+    -   `kernel.scale` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** the scale of the kernel in pixels. (optional, default `sum`)
+    -   `kernel.offset` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** a value in the range 0-255 representing the level at which the threshold will be applied. (optional, default `128`)
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `options.greyscale` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** convert to single channel greyscale. (optional, default `true`)
+    -   `options.grayscale` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** alternative spelling for greyscale. (optional, default `true`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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](https://nodejs.org/api/buffer.html) \| [String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String))** Buffer containing image data or String containing the path to an image file.
+-   `operator` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `options.raw` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** describes operand when using raw pixel data.
+        -   `options.raw.width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+        -   `options.raw.channels` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 

docs/api-output.md

@@ -0,0 +1,190 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [toFile](#tofile)
+-   [toBuffer](#tobuffer)
+-   [withMetadata](#withmetadata)
+-   [jpeg](#jpeg)
+-   [png](#png)
+-   [webp](#webp)
+-   [tiff](#tiff)
+-   [raw](#raw)
+-   [toFormat](#toformat)
+-   [tile](#tile)
+
+## 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 Promises/A+ promise is returned when `callback` is not provided.
+
+**Parameters**
+
+-   `fileOut` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)** the path to write the image data to.
+-   `callback` **[Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function)?** called on completion with two arguments `(err, info)`.
+    `info` contains the output image `format`, `size` (bytes), `width`, `height` and `channels`.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise)&lt;[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)>** when no callback is provided
+
+## toBuffer
+
+Write output to a Buffer.
+JPEG, PNG, WebP, 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, buffer, info)` where:
+
+-   `err` is an error message, if any.
+-   `buffer` is the output image data.
+-   `info` contains the output image `format`, `size` (bytes), `width`, `height` and `channels`.
+    A Promises/A+ promise is returned when `callback` is not provided.
+
+**Parameters**
+
+-   `callback` **[Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function)?** 
+
+Returns **[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise)&lt;[Buffer](https://nodejs.org/api/buffer.html)>** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `withMetadata.orientation` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** value between 1 and 8, used to update the EXIF `Orientation` tag.
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## jpeg
+
+Use these JPEG options for output image.
+
+**Parameters**
+
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** output options
+    -   `options.quality` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** quality, integer 1-100 (optional, default `80`)
+    -   `options.progressive` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** use progressive (interlace) scan (optional, default `false`)
+    -   `options.chromaSubsampling` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** set to '4:4:4' to prevent chroma subsampling when quality &lt;= 90 (optional, default `'4:2:0'`)
+    -   `options.trellisQuantisation` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** apply trellis quantisation, requires mozjpeg (optional, default `false`)
+    -   `options.overshootDeringing` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** apply overshoot deringing, requires mozjpeg (optional, default `false`)
+    -   `options.optimiseScans` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** optimise progressive scans, forces progressive, requires mozjpeg (optional, default `false`)
+    -   `options.optimizeScans` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** alternative spelling of optimiseScans (optional, default `false`)
+    -   `options.force` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** force JPEG output, otherwise attempt to use input format (optional, default `true`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid options
+
+Returns **Sharp** 
+
+## png
+
+Use these PNG options for output image.
+
+**Parameters**
+
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `options.progressive` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** use progressive (interlace) scan (optional, default `false`)
+    -   `options.compressionLevel` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** zlib compression level (optional, default `6`)
+    -   `options.adaptiveFiltering` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** use adaptive row filtering (optional, default `true`)
+    -   `options.force` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** force PNG output, otherwise attempt to use input format (optional, default `true`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid options
+
+Returns **Sharp** 
+
+## webp
+
+Use these WebP options for output image.
+
+**Parameters**
+
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** output options
+    -   `options.quality` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** quality, integer 1-100 (optional, default `80`)
+    -   `options.force` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** force WebP output, otherwise attempt to use input format (optional, default `true`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid options
+
+Returns **Sharp** 
+
+## tiff
+
+Use these TIFF options for output image.
+
+**Parameters**
+
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** output options
+    -   `options.quality` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** quality, integer 1-100 (optional, default `80`)
+    -   `options.force` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** force TIFF output, otherwise attempt to use input format (optional, default `true`)
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid options
+
+Returns **Sharp** 
+
+## raw
+
+Force output to be raw, uncompressed uint8 pixel data.
+
+Returns **Sharp** 
+
+## toFormat
+
+Force output to a given format.
+
+**Parameters**
+
+-   `format` **([String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String) \| [Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object))** as a String or an Object with an 'id' attribute
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** output options
+
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** 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.
+
+**Parameters**
+
+-   `tile` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `tile.size` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
+    -   `tile.overlap` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
+    -   `tile.container` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
+    -   `tile.layout` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 

docs/api-resize.md

@@ -0,0 +1,176 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [resize](#resize)
+-   [crop](#crop)
+-   [embed](#embed)
+-   [max](#max)
+-   [min](#min)
+-   [ignoreAspectRatio](#ignoreaspectratio)
+-   [withoutEnlargement](#withoutenlargement)
+
+## resize
+
+Resize image to `width` x `height`.
+By default, the resized image is centre cropped to the exact size specified.
+
+Possible reduction kernels are:
+
+-   `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
+-   `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).
+
+Possible enlargement interpolators are:
+
+-   `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
+-   `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
+-   `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
+-   `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
+-   `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)" but typically reduces performance by a factor of 2.
+-   `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
+
+**Parameters**
+
+-   `width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** pixels wide the resultant image should be, between 1 and 16383 (0x3FFF). Use `null` or `undefined` to auto-scale the width to match the height.
+-   `height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** pixels high the resultant image should be, between 1 and 16383. Use `null` or `undefined` to auto-scale the height to match the width.
+-   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
+    -   `options.kernel` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** the kernel to use for image reduction. (optional, default `'lanczos3'`)
+    -   `options.interpolator` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** the interpolator to use for image enlargement. (optional, default `'bicubic'`)
+    -   `options.centreSampling` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** use \*magick centre sampling convention instead of corner sampling. (optional, default `false`)
+    -   `options.centerSampling` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** alternative spelling of centreSampling. (optional, default `false`)
+
+**Examples**
+
+```javascript
+sharp(inputBuffer)
+  .resize(200, 300, {
+    kernel: sharp.kernel.lanczos2,
+    interpolator: 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 lanczos2/nohalo scaled version, embedded on a white canvas,
+    // of the image data in inputBuffer
+  });
+```
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## crop
+
+Crop the resized image to the exact size specified, the default behaviour.
+
+Possible attributes of the optional `sharp.gravity` are `north`, `northeast`, `east`, `southeast`, `south`,
+`southwest`, `west`, `northwest`, `center` and `centre`.
+
+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.
+
+**Parameters**
+
+-   `crop` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** A member of `sharp.gravity` to crop to an edge/corner or `sharp.strategy` to crop dynamically. (optional, default `'centre'`)
+
+**Examples**
+
+```javascript
+const transformer = sharp()
+  .resize(200, 200)
+  .crop(sharp.strategy.entropy)
+  .on('error', function(err) {
+    console.log(err);
+  });
+// Read image data from readableStream
+// Write 200px square auto-cropped image data to writableStream
+readableStream.pipe(transformer).pipe(writableStream);
+```
+
+-   Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** Invalid parameters
+
+Returns **Sharp** 
+
+## 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.
+
+**Examples**
+
+```javascript
+sharp('input.gif')
+  .resize(200, 300)
+  .background({r: 0, g: 0, b: 0, alpha: 0})
+  .embed()
+  .toFormat(sharp.format.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
+  });
+```
+
+Returns **Sharp** 
+
+## max
+
+Preserving aspect ratio, resize the image to be as large as possible
+while ensuring its dimensions are less than or equal to the `width` and `height` specified.
+
+Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
+
+**Examples**
+
+```javascript
+sharp(inputBuffer)
+  .resize(200, 200)
+  .max()
+  .toFormat('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
+  });
+```
+
+Returns **Sharp** 
+
+## min
+
+Preserving aspect ratio, resize the image to be as small as possible
+while ensuring its dimensions are greater than or equal to the `width` and `height` specified.
+
+Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
+
+Returns **Sharp** 
+
+## ignoreAspectRatio
+
+Ignoring the aspect ratio of the input, stretch the image to
+the exact `width` and/or `height` provided via `resize`.
+
+Returns **Sharp** 
+
+## 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_".
+
+**Parameters**
+
+-   `withoutEnlargement` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `true`)
+
+Returns **Sharp** 

docs/api-utility.md

@@ -0,0 +1,106 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+### Table of Contents
+
+-   [cache](#cache)
+-   [concurrency](#concurrency)
+-   [counters](#counters)
+-   [simd](#simd)
+
+## 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) \| [Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean))** Object with the following attributes, or Boolean where true uses default cache settings and false removes all caching.
+    -   `options.memory` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** is the maximum memory in MB to use for this cache (optional, default `50`)
+    -   `options.files` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** is the maximum number of files to hold open (optional, default `20`)
+    -   `options.items` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+
+## 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** 
+
+**Examples**
+
+```javascript
+const threads = sharp.concurrency(); // 4
+sharp.concurrency(2); // 2
+sharp.concurrency(0); // 4
+```
+
+Returns **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)** 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](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** 
+
+## 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.
+
+This feature is currently off by default but future versions may reverse this.
+Versions of liborc prior to 0.4.25 are known to segfault under heavy load.
+
+**Parameters**
+
+-   `simd` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?**  (optional, default `false`)
+
+**Examples**
+
+```javascript
+const simd = sharp.simd();
+// simd is `true` if SIMD is currently enabled
+```
+
+```javascript
+const simd = sharp.simd(true);
+// attempts to enable the use of SIMD, returning true if available
+```
+
+Returns **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** 

docs/changelog.md

@@ -0,0 +1,503 @@
+# Changelog
+
+### v0.17 - "*quill*"
+
+Requires libvips v8.4.2.
+
+#### 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/index.md

@@ -0,0 +1,116 @@
+# sharp
+
+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.
+
+OS X, Windows (x64), Linux (x64, ARM) systems do not require
+the installation of any external 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 and WebP 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/jcupitt/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/A+ 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 can be disabled,
+which for diagrams and line art often produces the same result
+as [pngcrush](http://pmt.sourceforge.net/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)
+
+Thank you!
+
+### Licence
+
+Copyright 2013, 2014, 2015, 2016, 2017 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)
+
+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 +1,215 @@
+# Installation
+
+```sh
+npm install sharp
+```
+
+```sh
+yarn add sharp
+```
+
+### Prerequisites
+
+* Node v4+
+* C++11 compatible compiler such as gcc 4.8+, clang 3.0+ or MSVC 2013+
+* [node-gyp](https://github.com/TooTallNate/node-gyp#installation) and its dependencies
+
+### Linux
+
+[![Ubuntu 14.04 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+[![Linux Build Status](https://circleci.com/gh/lovell/sharp.svg?style=svg&circle-token=6cb6d1d287a51af83722b19ed8885377fbc85e5c)](https://circleci.com/gh/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 6.5MB.
+
+Most recent Linux-based operating systems with glibc running on x64 and ARMv6+ CPUs should "just work", e.g.:
+
+* Debian 7, 8
+* Ubuntu 12.04, 14.04, 16.04
+* Centos 7
+* Fedora 23, 24
+* openSUSE 13.2
+* Archlinux
+* Raspbian Jessie
+* Amazon Linux 2016.03, 2016.09
+
+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-stadard 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,
+it is recommended to install a system-wide installation of libvips from source:
+
+https://github.com/jcupitt/libvips#building-libvips-from-a-source-tarball
+
+For Linux-based operating systems such as Alpine that use musl libc,
+the smaller stack size means libvips' cache should be disabled
+via `sharp.cache(false)` to avoid a stack overflow.
+
+### Mac OS
+
+[![OS X 10.9.5 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 6.3MB.
+
+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 9MB.
+
+Only 64-bit (x64) `node.exe` is supported.
+
+### FreeBSD
+
+libvips must be installed before `npm install` is run.
+This can be achieved via [FreshPorts](https://www.freshports.org/graphics/vips/):
+
+```sh
+cd /usr/ports/graphics/vips/ && make install clean
+```
+
+### Heroku
+
+[Alessandro Tagliapietra](https://github.com/alex88) maintains an
+[Heroku buildpack for libvips](https://github.com/alex88/heroku-buildpack-vips)
+and its dependencies.
+
+### 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
+```
+
+### AWS Lambda
+
+In order to use sharp on AWS Lambda, you need to [create a deployment package](http://docs.aws.amazon.com/lambda/latest/dg/nodejs-create-deployment-pkg.html). Because sharp
+downloads and links libraries for the current platform during `npm install` you have to
+do this on a system similar to the [Lambda Execution Environment](http://docs.aws.amazon.com/lambda/latest/dg/current-supported-versions.html). The easiest ways to do this, is to setup a
+small t2.micro instance using the AMI ID listed in the previous link, ssh into it as ec2-user
+and follow the instructions below.
+
+Install dependencies:
+
+```sh
+curl -s https://rpm.nodesource.com/setup_4.x | sudo bash -
+sudo yum install -y gcc-c++ nodejs
+```
+
+Copy your code and package.json to the instance using `scp` and create a deployment package:
+
+```sh
+cd sharp-lambda-example
+npm install
+zip -ur9 ../sharp-lambda-example.zip index.js node_modules
+```
+
+You can now download your deployment ZIP using `scp` and upload it to Lambda. Be sure to set your Lambda runtime to Node.js 4.3.
+
+**Performance Tip:** To get the best performance on Lambda choose the largest memory available because this also gives you the most cpu time (a 1536 MB function is 12x faster than a 128 MB function).
+
+### Build tools
+
+* [gulp-responsive](https://www.npmjs.com/package/gulp-responsive)
+* [grunt-sharp](https://www.npmjs.com/package/grunt-sharp)
+
+### 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.
+
+ImageMagick in particular has a relatively large attack surface,
+which can be partially mitigated with a
+[policy.xml](http://www.imagemagick.org/script/resources.php)
+configuration file to prevent the use of coders known to be vulnerable.
+
+```xml
+<policymap>
+  <policy domain="coder" rights="none" pattern="EPHEMERAL" />
+  <policy domain="coder" rights="none" pattern="URL" />
+  <policy domain="coder" rights="none" pattern="HTTPS" />
+  <policy domain="coder" rights="none" pattern="MVG" />
+  <policy domain="coder" rights="none" pattern="MSL" />
+  <policy domain="coder" rights="none" pattern="TEXT" />
+  <policy domain="coder" rights="none" pattern="SHOW" />
+  <policy domain="coder" rights="none" pattern="WIN" />
+  <policy domain="coder" rights="none" pattern="PLT" />
+</policymap>
+```
+
+Set the `MAGICK_CONFIGURE_PATH` environment variable
+to the directory containing the `policy.xml` file.
+
+### Licences
+
+If a global installation of libvips that meets the
+minimum version requirement cannot be found,
+this module will download a pre-compiled bundle of libvips
+and its dependencies on Linux and Windows machines.
+
+Should you need to manually download and inspect these files,
+you can do so via https://dl.bintray.com/lovell/sharp/
+
+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                                                                               |
+| 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) |
+| 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 +1,73 @@
+# Performance
+
+### Test environment
+
+* AWS EC2 eu-central-1 [c4.xlarge](http://aws.amazon.com/ec2/instance-types/#c4) (4x E5-2666 v3 @ 2.90GHz)
+* Ubuntu 16.04.1 LTS (HVM, SSD, 20161115, ami-82cf0aed)
+* Node.js v6.9.1
+
+### The contenders
+
+* [jimp](https://www.npmjs.com/package/jimp) v0.2.27 - Image processing in pure JavaScript. Bilinear interpolation only.
+* [lwip](https://www.npmjs.com/package/lwip) v0.0.9 - Wrapper around CImg. Compiles outdated, insecure dependencies from source.
+* [mapnik](https://www.npmjs.org/package/mapnik) v3.5.14 - 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) v1.23.0 - Fully featured wrapper around GraphicsMagick's `gm` command line utility.
+* sharp v0.17.0 / libvips v8.4.2 - 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 (bilinear)    | buffer | buffer |    1.06 |      1.0 |
+| lwip               | buffer | buffer |    1.87 |      1.8 |
+| mapnik             | buffer | buffer |    2.91 |      2.7 |
+| imagemagick-native | buffer | buffer |    4.03 |      3.8 |
+| imagemagick        | file   | file   |    7.10 |      6.7 |
+| gm                 | buffer | buffer |    7.08 |      6.7 |
+| gm                 | file   | file   |    7.10 |      6.7 |
+| sharp              | stream | stream |   27.61 |     26.0 |
+| sharp              | file   | file   |   28.41 |     26.8 |
+| sharp              | buffer | file   |   28.71 |     27.1 |
+| sharp              | file   | buffer |   28.60 |     27.0 |
+| sharp              | buffer | buffer |   29.08 |     27.4 |
+
+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 both _ImageMagick_ and _GraphicsMagick_:
+
+```sh
+brew install imagemagick
+brew install graphicsmagick
+```
+
+```sh
+sudo apt-get install imagemagick libmagick++-dev graphicsmagick
+```
+
+```sh
+sudo yum install ImageMagick-devel ImageMagick-c++-devel GraphicsMagick
+```
+
+### 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

@@ -1,414 +0,0 @@
-/*jslint node: true */
-'use strict';
-
-var util = require('util');
-var stream = require('stream');
-var Promise = require('bluebird');
-var sharp = require('./build/Release/sharp');
-
-var Sharp = function(input) {
-  if (!(this instanceof Sharp)) {
-    return new Sharp(input);
-  }
-  stream.Duplex.call(this);
-  this.options = {
-    width: -1,
-    height: -1,
-    canvas: 'c',
-    gravity: 0,
-    angle: 0,
-    withoutEnlargement: false,
-    sharpen: false,
-    interpolator: 'bilinear',
-    progressive: false,
-    sequentialRead: false,
-    quality: 80,
-    compressionLevel: 6,
-    streamIn: false,
-    streamOut: false,
-    output: '__input'
-  };
-  if (typeof input === 'string') {
-    // input=file
-    this.options.fileIn = input;
-  } else if (typeof input === 'object' && input instanceof Buffer) {
-    // input=buffer
-    if (input.length > 0) {
-      this.options.bufferIn = input;
-    } else {
-      throw new Error('Buffer is empty');
-    }
-  } 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) {
-  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 !== 'undefined') {
-    // Is this a supported gravity?
-    if (!Number.isNaN(gravity) && gravity >= 0 && gravity <= 4) {
-      this.options.gravity = gravity;
-    } else {
-      throw new Error('Unsupported crop gravity ' + gravity);
-    }
-  }
-  return this;
-};
-
-Sharp.prototype.embedWhite = function() {
-  this.options.canvas = 'w';
-  return this;
-};
-
-Sharp.prototype.embedBlack = function() {
-  this.options.canvas = 'b';
-  return this;
-};
-
-Sharp.prototype.max = function() {
-  this.options.canvas = 'm';
-  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;
-};
-
-/*
-  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;
-};
-
-Sharp.prototype.sharpen = function(sharpen) {
-  this.options.sharpen = (typeof sharpen === 'boolean') ? sharpen : true;
-  return this;
-};
-
-/*
-  Set the interpolator to use for the affine transformation
-*/
-module.exports.interpolator = {
-  bilinear: 'bilinear',
-  bicubic: 'bicubic',
-  nohalo: 'nohalo',
-  locallyBoundedBicubic: 'lbb',
-  vertexSplitQuadraticBasisSpline: 'vsqbs'
-};
-Sharp.prototype.interpolateWith = function(interpolator) {
-  this.options.interpolator = interpolator;
-  return this;
-};
-
-/*
-  Deprecated interpolation methods, to be removed in v0.7.0
-*/
-Sharp.prototype.bilinearInterpolation = util.deprecate(function() {
-  return this.interpolateWith(module.exports.interpolator.bilinear);
-}, 'bilinearInterpolation() is deprecated, use interpolateWith(sharp.interpolator.bilinear) instead');
-Sharp.prototype.bicubicInterpolation = util.deprecate(function() {
-  return this.interpolateWith(module.exports.interpolator.bicubic);
-}, 'bicubicInterpolation() is deprecated, use interpolateWith(sharp.interpolator.bicubic) instead');
-Sharp.prototype.nohaloInterpolation = util.deprecate(function() {
-  return this.interpolateWith(module.exports.interpolator.nohalo);
-}, 'nohaloInterpolation() is deprecated, use interpolateWith(sharp.interpolator.nohalo) instead');
-
-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;
-};
-
-Sharp.prototype.compressionLevel = function(compressionLevel) {
-  if (!Number.isNaN(compressionLevel) && compressionLevel >= -1 && compressionLevel <= 9) {
-    this.options.compressionLevel = compressionLevel;
-  } else {
-    throw new Error('Invalid compressionLevel (-1 to 9) ' + compressionLevel);
-  }
-  return this;
-};
-
-Sharp.prototype.resize = function(width, height) {
-  if (!width) {
-    this.options.width = -1;
-  } else {
-    if (!Number.isNaN(width)) {
-      this.options.width = width;
-    } else {
-      throw new Error('Invalid width ' + width);
-    }
-  }
-  if (!height) {
-    this.options.height = -1;
-  } else {
-    if (!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 Promise.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 Promise.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';
-  if (arguments.length > 0) {
-    console.error('Use of the jpeg() method with a callback is deprecated in 0.6.x and will be removed in 0.7.x');
-    console.error('Please add toFile(), toBuffer() or Stream methods e.g. pipe() for JPEG output');
-    this._sharp(arguments);
-  }
-  return this;
-};
-
-Sharp.prototype.png = function() {
-  this.options.output = '__png';
-  if (arguments.length > 0) {
-    console.error('Use of the png() method with a callback is deprecated in 0.6.x and will be removed in 0.7.x');
-    console.error('Please add toFile(), toBuffer() or Stream methods e.g. pipe() for PNG output');
-    this._sharp(arguments);
-  }
-  return this;
-};
-
-Sharp.prototype.webp = function() {
-  this.options.output = '__webp';
-  if (arguments.length > 0) {
-    console.error('Use of the webp() method with a callback is deprecated in 0.6.x and will be removed in 0.7.x');
-    console.error('Please add toFile(), toBuffer() or Stream methods e.g. pipe() for WebP output');
-    this._sharp(arguments);
-  }
-  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) throw err;
-          that.push(data);
-          that.push(null);
-        });
-      });
-    } else {
-      // output=stream, input=file/buffer
-      sharp.resize(this.options, function(err, data) {
-        if (err) throw err;
-        that.push(data);
-        that.push(null);
-      });
-    }
-    return this;
-  } else {
-    // output=promise
-    if (this.options.streamIn) {
-      // output=promise, input=stream
-      return new Promise(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 Promise(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 Promise(function(resolve, reject) {
-        that.on('finish', function() {
-          sharp.metadata(that.options, function(err, data) {
-            if (err) {
-              reject(err);
-            } else {
-              resolve(data);
-            }
-          });
-        });
-      });
-    } else {
-      return new Promise(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 (Number.isNaN(memory)) {
-    memory = null;
-  }
-  if (Number.isNaN(items)) {
-    items = null;
-  }
-  return sharp.cache(memory, items);
-};
-
-/*
-  Get internal counters
-*/
-module.exports.counters = function() {
-  return sharp.counters();
-};

lib/channel.js

@@ -0,0 +1,113 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Boolean operations for bandbool.
+ * @private
+ */
+const bool = {
+  and: 'and',
+  or: 'or',
+  eor: 'eor'
+};
+
+/**
+ * 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
+ */
+const extractChannel = 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
+ */
+const joinChannel = 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
+ */
+const bandbool = 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) {
+  // Public instance functions
+  [
+    extractChannel,
+    joinChannel,
+    bandbool
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.bool = bool;
+};

lib/colour.js

@@ -0,0 +1,108 @@
+'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'
+};
+
+/**
+ * Set the background for the `embed`, `flatten` and `extend` operations.
+ * The default background is `{r: 0, g: 0, b: 0, alpha: 1}`, black without transparency.
+ *
+ * Delegates to the _color_ module, which can throw an Error
+ * but is liberal in what it accepts, clipping values to sensible min/max.
+ * The alpha value is a float between `0` (transparent) and `1` (opaque).
+ *
+ * @param {String|Object} rgba - 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 parameter
+ */
+const background = function background (rgba) {
+  const colour = color(rgba);
+  this.options.background = [
+    colour.red(),
+    colour.green(),
+    colour.blue(),
+    Math.round(colour.alpha() * 255)
+  ];
+  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}
+ */
+const greyscale = function greyscale (greyscale) {
+  this.options.greyscale = is.bool(greyscale) ? greyscale : true;
+  return this;
+};
+
+/**
+ * Alternative spelling of `greyscale`.
+ * @param {Boolean} [grayscale=true]
+ * @returns {Sharp}
+ */
+const grayscale = 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/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const toColourspace = 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
+ */
+const toColorspace = function toColorspace (colorspace) {
+  return this.toColourspace(colorspace);
+};
+
+/**
+ * Decorate the Sharp prototype with colour-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  // Public instance functions
+  [
+    background,
+    greyscale,
+    grayscale,
+    toColourspace,
+    toColorspace
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.colourspace = colourspace;
+  Sharp.colorspace = colourspace;
+};

lib/composite.js

@@ -0,0 +1,92 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Overlay (composite) an image over the processed (resized, extracted etc.) image.
+ *
+ * The overlay image must be the same size or smaller than the processed image.
+ * If both `top` and `left` options are provided, they take precedence over `gravity`.
+ *
+ * @example
+ * sharp('input.png')
+ *   .rotate(180)
+ *   .resize(300)
+ *   .flatten()
+ *   .background('#ff6600')
+ *   .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
+ *   .sharpen()
+ *   .withMetadata()
+ *   .quality(90)
+ *   .webp()
+ *   .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 {(Buffer|String)} overlay - Buffer containing image data or String containing the path to an image file.
+ * @param {Object} [options]
+ * @param {String} [options.gravity='centre'] - gravity at which to place the overlay.
+ * @param {Number} [options.top] - the pixel offset from the top edge.
+ * @param {Number} [options.left] - the pixel offset from the left edge.
+ * @param {Boolean} [options.tile=false] - set to true to repeat the overlay image across the entire image with the given `gravity`.
+ * @param {Boolean} [options.cutout=false] - set to true to apply only the alpha channel of the overlay image to the input image, giving the appearance of one image being cut out of another.
+ * @param {Object} [options.raw] - describes overlay 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
+ */
+const overlayWith = function overlayWith (overlay, options) {
+  this.options.overlay = this._createInputDescriptor(overlay, options, {
+    allowStream: false
+  });
+  if (is.object(options)) {
+    if (is.defined(options.tile)) {
+      if (is.bool(options.tile)) {
+        this.options.overlayTile = options.tile;
+      } else {
+        throw new Error('Invalid overlay tile ' + options.tile);
+      }
+    }
+    if (is.defined(options.cutout)) {
+      if (is.bool(options.cutout)) {
+        this.options.overlayCutout = options.cutout;
+      } else {
+        throw new Error('Invalid overlay cutout ' + options.cutout);
+      }
+    }
+    if (is.defined(options.left) || is.defined(options.top)) {
+      if (
+        is.integer(options.left) && is.inRange(options.left, 0, this.constructor.maximum.width) &&
+        is.integer(options.top) && is.inRange(options.top, 0, this.constructor.maximum.height)
+      ) {
+        this.options.overlayXOffset = options.left;
+        this.options.overlayYOffset = options.top;
+      } else {
+        throw new Error('Invalid overlay left ' + options.left + ' and/or top ' + options.top);
+      }
+    }
+    if (is.defined(options.gravity)) {
+      if (is.integer(options.gravity) && is.inRange(options.gravity, 0, 8)) {
+        this.options.overlayGravity = options.gravity;
+      } else if (is.string(options.gravity) && is.integer(this.constructor.gravity[options.gravity])) {
+        this.options.overlayGravity = this.constructor.gravity[options.gravity];
+      } else {
+        throw new Error('Unsupported overlay gravity ' + options.gravity);
+      }
+    }
+  }
+  return this;
+};
+
+/**
+ * Decorate the Sharp prototype with composite-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  Sharp.prototype.overlayWith = overlayWith;
+};

lib/constructor.js

@@ -0,0 +1,206 @@
+'use strict';
+
+const path = require('path');
+const util = require('util');
+const stream = require('stream');
+const events = require('events');
+const semver = require('semver');
+const sharp = require('../build/Release/sharp.node');
+
+// Versioning
+let versions = {
+  vips: sharp.libvipsVersion()
+};
+(function () {
+  // Does libvips meet minimum requirement?
+  const libvipsVersionMin = require('../package.json').config.libvips;
+  /* istanbul ignore if */
+  if (semver.lt(versions.vips, libvipsVersionMin)) {
+    throw new Error('Found libvips ' + versions.vips + ' but require at least ' + libvipsVersionMin);
+  }
+  // Include versions of dependencies, if present
+  try {
+    versions = require('../vendor/lib/versions.json');
+  } catch (err) {}
+})();
+
+/**
+ * @class Sharp
+ *
+ * Constructor factory to create an instance of `sharp`, to which further methods are chained.
+ *
+ * JPEG, PNG or WebP 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);
+ *
+ * @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 null or undefined.
+ * @param {Object} [options] - if present, is an Object with optional attributes.
+ * @param {Number} [options.density=72] - integral number representing the DPI for vector images.
+ * @param {Object} [options.raw] - describes raw pixel image data. See `raw()` for pixel ordering.
+ * @param {Number} [options.raw.width]
+ * @param {Number} [options.raw.height]
+ * @param {Number} [options.raw.channels]
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const Sharp = function (input, options) {
+  if (!(this instanceof Sharp)) {
+    return new Sharp(input, options);
+  }
+  stream.Duplex.call(this);
+  this.options = {
+    // input options
+    sequentialRead: false,
+    limitInputPixels: maximum.pixels,
+    // 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',
+    crop: 0,
+    angle: 0,
+    rotateBeforePreExtract: false,
+    flip: false,
+    flop: false,
+    extendTop: 0,
+    extendBottom: 0,
+    extendLeft: 0,
+    extendRight: 0,
+    withoutEnlargement: false,
+    kernel: 'lanczos3',
+    interpolator: 'bicubic',
+    centreSampling: false,
+    // operations
+    background: [0, 0, 0, 255],
+    flatten: false,
+    negate: false,
+    blurSigma: 0,
+    sharpenSigma: 0,
+    sharpenFlat: 1,
+    sharpenJagged: 2,
+    threshold: 0,
+    thresholdGrayscale: true,
+    trimTolerance: 0,
+    gamma: 0,
+    greyscale: false,
+    normalise: 0,
+    booleanBufferIn: null,
+    booleanFileIn: '',
+    joinChannelIn: [],
+    extractChannel: -1,
+    colourspace: 'srgb',
+    // overlay
+    overlayGravity: 0,
+    overlayXOffset: -1,
+    overlayYOffset: -1,
+    overlayTile: false,
+    overlayCutout: false,
+    // output
+    fileOut: '',
+    formatOut: 'input',
+    streamOut: false,
+    withMetadata: false,
+    withMetadataOrientation: -1,
+    // output format
+    jpegQuality: 80,
+    jpegProgressive: false,
+    jpegChromaSubsampling: '4:2:0',
+    jpegTrellisQuantisation: false,
+    jpegOvershootDeringing: false,
+    jpegOptimiseScans: false,
+    pngProgressive: false,
+    pngCompressionLevel: 6,
+    pngAdaptiveFiltering: true,
+    webpQuality: 80,
+    tiffQuality: 80,
+    tileSize: 256,
+    tileOverlap: 0,
+    // 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);
+
+/**
+ * Pixel limits.
+ * @member
+ * @private
+ */
+const maximum = {
+  width: 0x3FFF,
+  height: 0x3FFF,
+  pixels: Math.pow(0x3FFF, 2)
+};
+Sharp.maximum = maximum;
+
+/**
+ * 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 = versions;
+
+/**
+ * Export constructor.
+ * @private
+ */
+module.exports = Sharp;

lib/index.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const Sharp = require('./constructor');
+[
+  'input',
+  'resize',
+  'composite',
+  'operation',
+  'colour',
+  'channel',
+  'output',
+  'utility'
+].forEach(function (decorator) {
+  require('./' + decorator)(Sharp);
+});
+
+module.exports = Sharp;

lib/input.js

@@ -0,0 +1,252 @@
+'use strict';
+
+const util = require('util');
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Create Object containing input and input-related options.
+ * @private
+ */
+const _createInputDescriptor = function _createInputDescriptor (input, inputOptions, containerOptions) {
+  const inputDescriptor = {};
+  if (is.string(input)) {
+    // filesystem
+    inputDescriptor.file = input;
+  } else if (is.buffer(input)) {
+    // Buffer
+    inputDescriptor.buffer = input;
+  } 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)) {
+    // Density
+    if (is.defined(inputOptions.density)) {
+      if (is.integer(inputOptions.density) && 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) && is.inRange(inputOptions.raw.width, 1, this.constructor.maximum.width) &&
+        is.integer(inputOptions.raw.height) && is.inRange(inputOptions.raw.height, 1, this.constructor.maximum.height) &&
+        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');
+      }
+    }
+  } 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
+ */
+const _write = function _write (chunk, encoding, callback) {
+  /* istanbul ignore else */
+  if (Array.isArray(this.options.input.buffer)) {
+    /* istanbul ignore else */
+    if (is.buffer(chunk)) {
+      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
+ */
+const _flattenBufferIn = function _flattenBufferIn () {
+  if (this._isStreamInput()) {
+    this.options.input.buffer = Buffer.concat(this.options.input.buffer);
+  }
+};
+
+/**
+ * Are we expecting Stream-based input?
+ * @private
+ * @returns {Boolean}
+ */
+const _isStreamInput = 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}
+ */
+const clone = function clone () {
+  const that = this;
+  // Clone existing options
+  const clone = this.constructor.call();
+  util._extend(clone.options, this.options);
+  // Pass 'finish' event to clone for Stream-based input
+  this.on('finish', function () {
+    // Clone inherits input data
+    that._flattenBufferIn();
+    clone.options.bufferIn = that.options.bufferIn;
+    clone.emit('finish');
+  });
+  return clone;
+};
+
+/**
+ * Fast access to image metadata without decoding any compressed image data.
+ * A Promises/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`
+ * - `width`: Number of pixels wide
+ * - `height`: Number of pixels high
+ * - `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+ * - `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+ * - `density`: Number of pixels per inch (DPI), if present
+ * - `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
+ *
+ * @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}
+ */
+const metadata = 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);
+          }
+        });
+      });
+    }
+  }
+};
+
+/**
+ * Do not process input images where the number of pixels (width * height) exceeds this limit.
+ * Assumes image dimensions contained in the input metadata can be trusted.
+ * The default limit is 268402689 (0x3FFF * 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
+*/
+const limitInputPixels = 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 = this.constructor.maximum.pixels;
+  }
+  if (is.integer(limit) && limit >= 0) {
+    this.options.limitInputPixels = limit;
+  } else {
+    throw new Error('Invalid pixel limit (0 to ' + this.constructor.maximum.pixels + ') ' + 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.
+ * @param {Boolean} [sequentialRead=true]
+ * @returns {Sharp}
+ */
+const sequentialRead = 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) {
+  [
+    // Private
+    _createInputDescriptor,
+    _write,
+    _flattenBufferIn,
+    _isStreamInput,
+    // Public
+    clone,
+    metadata,
+    limitInputPixels,
+    sequentialRead
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+};

lib/is.js

@@ -0,0 +1,110 @@
+'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 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,
+  fn: fn,
+  bool: bool,
+  buffer: buffer,
+  string: string,
+  number: number,
+  integer: integer,
+  inRange: inRange,
+  inArray: inArray,
+  invalidParameterError: invalidParameterError
+};

lib/operation.js

@@ -0,0 +1,431 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Rotate the output image by either an explicit angle
+ * or auto-orient based on the EXIF `Orientation` tag.
+ *
+ * Use this method without angle to determine the angle from 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] 0, 90, 180 or 270.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const rotate = function rotate (angle) {
+  if (!is.defined(angle)) {
+    this.options.angle = -1;
+  } else if (is.integer(angle) && is.inArray(angle, [0, 90, 180, 270])) {
+    this.options.angle = angle;
+  } else {
+    throw new Error('Unsupported angle (0, 90, 180, 270) ' + angle);
+  }
+  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
+ */
+const extract = 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 !== 0) {
+    this.options.rotateBeforePreExtract = true;
+  }
+  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}
+ */
+const flip = 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}
+ */
+const flop = 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
+ */
+const sharpen = 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;
+};
+
+/**
+ * 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
+ */
+const blur = 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;
+};
+
+/**
+ * Extends/pads the edges of the image with the colour provided to the `background` method.
+ * 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)
+ *   .background({r: 0, g: 0, b: 0, alpha: 0})
+ *   .extend({top: 10, bottom: 20, left: 10, right: 10})
+ *   ...
+ *
+ * @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]
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+*/
+const extend = 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;
+  } else {
+    throw new Error('Invalid edge extension ' + extend);
+  }
+  return this;
+};
+
+/**
+ * Merge alpha transparency channel, if any, with `background`.
+ * @param {Boolean} [flatten=true]
+ * @returns {Sharp}
+ */
+const flatten = function flatten (flatten) {
+  this.options.flatten = is.bool(flatten) ? flatten : true;
+  return this;
+};
+
+/**
+ * Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel.
+ * @param {Number} [tolerance=10] value between 1 and 99 representing the percentage similarity.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const trim = function trim (tolerance) {
+  if (!is.defined(tolerance)) {
+    this.options.trimTolerance = 10;
+  } else if (is.integer(tolerance) && is.inRange(tolerance, 1, 99)) {
+    this.options.trimTolerance = tolerance;
+  } else {
+    throw new Error('Invalid trim tolerance (1 to 99) ' + tolerance);
+  }
+  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.
+ * @param {Number} [gamma=2.2] value between 1.0 and 3.0.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const gamma = function gamma (gamma) {
+  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);
+  }
+  return this;
+};
+
+/**
+ * Produce the "negative" of the image.
+ * @param {Boolean} [negate=true]
+ * @returns {Sharp}
+ */
+const negate = 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}
+ */
+const normalise = function normalise (normalise) {
+  this.options.normalise = is.bool(normalise) ? normalise : true;
+  return this;
+};
+
+/**
+ * Alternative spelling of normalise.
+ * @param {Boolean} [normalize=true]
+ * @returns {Sharp}
+ */
+const normalize = 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
+ */
+const convolve = 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
+ */
+const threshold = 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
+ */
+const boolean = 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;
+};
+
+/**
+ * Decorate the Sharp prototype with operation-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    rotate,
+    extract,
+    flip,
+    flop,
+    sharpen,
+    blur,
+    extend,
+    flatten,
+    trim,
+    gamma,
+    negate,
+    normalise,
+    normalize,
+    convolve,
+    threshold,
+    boolean
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+};

lib/output.js

@@ -0,0 +1,517 @@
+'use strict';
+
+const util = require('util');
+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 Promises/A+ promise is returned when `callback` is not provided.
+ *
+ * @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` and `channels`.
+ * @returns {Promise<Object>} - when no callback is provided
+ * @throws {Error} Invalid parameters
+ */
+const toFile = function toFile (fileOut, callback) {
+  if (!fileOut || fileOut.length === 0) {
+    const errOutputInvalid = new Error('Invalid output');
+    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, 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, buffer, info)` where:
+ * - `err` is an error message, if any.
+ * - `buffer` is the output image data.
+ * - `info` contains the output image `format`, `size` (bytes), `width`, `height` and `channels`.
+ * A Promises/A+ promise is returned when `callback` is not provided.
+ *
+ * @param {Function} [callback]
+ * @returns {Promise<Buffer>} - when no callback is provided
+ */
+const toBuffer = function toBuffer (callback) {
+  return this._pipeline(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.
+ * @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
+ */
+const withMetadata = 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.
+ * @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.force=true] - force JPEG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+const jpeg = 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);
+      }
+    }
+    options.trellisQuantisation = is.bool(options.trellisQuantization) ? options.trellisQuantization : options.trellisQuantisation;
+    if (is.defined(options.trellisQuantisation)) {
+      this._setBooleanOption('jpegTrellisQuantisation', options.trellisQuantisation);
+    }
+    if (is.defined(options.overshootDeringing)) {
+      this._setBooleanOption('jpegOvershootDeringing', options.overshootDeringing);
+    }
+    options.optimiseScans = is.bool(options.optimizeScans) ? options.optimizeScans : options.optimiseScans;
+    if (is.defined(options.optimiseScans)) {
+      this._setBooleanOption('jpegOptimiseScans', options.optimiseScans);
+      if (options.optimiseScans) {
+        this.options.jpegProgressive = true;
+      }
+    }
+  }
+  return this._updateFormatOut('jpeg', options);
+};
+
+/**
+ * Use these PNG options for output image.
+ * @param {Object} [options]
+ * @param {Boolean} [options.progressive=false] - use progressive (interlace) scan
+ * @param {Number} [options.compressionLevel=6] - zlib compression level
+ * @param {Boolean} [options.adaptiveFiltering=true] - use adaptive row filtering
+ * @param {Boolean} [options.force=true] - force PNG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+const png = 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);
+    }
+  }
+  return this._updateFormatOut('png', options);
+};
+
+/**
+ * Use these WebP options for output image.
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Boolean} [options.force=true] - force WebP output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+const webp = 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);
+    }
+  }
+  return this._updateFormatOut('webp', options);
+};
+
+/**
+ * Use these TIFF options for output image.
+ * @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
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+const tiff = function tiff (options) {
+  if (is.object(options) && 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);
+    }
+  }
+  return this._updateFormatOut('tiff', options);
+};
+
+/**
+ * Force output to be raw, uncompressed uint8 pixel data.
+ * @returns {Sharp}
+ */
+const raw = function raw () {
+  return this._updateFormatOut('raw');
+};
+
+/**
+ * Force output to a given format.
+ * @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
+ */
+const toFormat = function toFormat (format, options) {
+  if (is.object(format) && is.string(format.id)) {
+    format = format.id;
+  }
+  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.
+ *
+ * @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 {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
+ */
+const tile = 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);
+      }
+    }
+  }
+  // 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}
+ */
+const _updateFormatOut = function _updateFormatOut (formatOut, options) {
+  this.options.formatOut = (is.object(options) && options.force === false) ? 'input' : formatOut;
+  return this;
+};
+
+/**
+ * Update a Boolean attribute of the this.options Object.
+ * @private
+ * @param {String} key
+ * @param {Boolean} val
+ * @throws {Error} Invalid key
+ */
+const _setBooleanOption = 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
+ */
+const _read = 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
+ */
+const _pipeline = 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
+      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) {
+            if (err) {
+              reject(err);
+            } else {
+              resolve(data);
+            }
+          });
+        });
+      });
+    } else {
+      // output=promise, input=file/buffer
+      return new Promise(function (resolve, reject) {
+        sharp.pipeline(that.options, function (err, data) {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(data);
+          }
+        });
+      });
+    }
+  }
+};
+
+// Deprecated output options
+/* istanbul ignore next */
+const quality = util.deprecate(function (quality) {
+  const formatOut = this.options.formatOut;
+  const options = { quality: quality };
+  this.jpeg(options).webp(options).tiff(options);
+  this.options.formatOut = formatOut;
+  return this;
+}, 'quality: use jpeg({ quality: ... }), webp({ quality: ... }) and/or tiff({ quality: ... }) instead');
+/* istanbul ignore next */
+const progressive = util.deprecate(function (progressive) {
+  const formatOut = this.options.formatOut;
+  const options = { progressive: (progressive !== false) };
+  this.jpeg(options).png(options);
+  this.options.formatOut = formatOut;
+  return this;
+}, 'progressive: use jpeg({ progressive: ... }) and/or png({ progressive: ... }) instead');
+/* istanbul ignore next */
+const compressionLevel = util.deprecate(function (compressionLevel) {
+  const formatOut = this.options.formatOut;
+  this.png({ compressionLevel: compressionLevel });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'compressionLevel: use png({ compressionLevel: ... }) instead');
+/* istanbul ignore next */
+const withoutAdaptiveFiltering = util.deprecate(function (withoutAdaptiveFiltering) {
+  const formatOut = this.options.formatOut;
+  this.png({ adaptiveFiltering: (withoutAdaptiveFiltering === false) });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'withoutAdaptiveFiltering: use png({ adaptiveFiltering: ... }) instead');
+/* istanbul ignore next */
+const withoutChromaSubsampling = util.deprecate(function (withoutChromaSubsampling) {
+  const formatOut = this.options.formatOut;
+  this.jpeg({ chromaSubsampling: (withoutChromaSubsampling === false) ? '4:2:0' : '4:4:4' });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'withoutChromaSubsampling: use jpeg({ chromaSubsampling: "4:4:4" }) instead');
+/* istanbul ignore next */
+const trellisQuantisation = util.deprecate(function (trellisQuantisation) {
+  const formatOut = this.options.formatOut;
+  this.jpeg({ trellisQuantisation: (trellisQuantisation !== false) });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'trellisQuantisation: use jpeg({ trellisQuantisation: ... }) instead');
+/* istanbul ignore next */
+const overshootDeringing = util.deprecate(function (overshootDeringing) {
+  const formatOut = this.options.formatOut;
+  this.jpeg({ overshootDeringing: (overshootDeringing !== false) });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'overshootDeringing: use jpeg({ overshootDeringing: ... }) instead');
+/* istanbul ignore next */
+const optimiseScans = util.deprecate(function (optimiseScans) {
+  const formatOut = this.options.formatOut;
+  this.jpeg({ optimiseScans: (optimiseScans !== false) });
+  this.options.formatOut = formatOut;
+  return this;
+}, 'optimiseScans: use jpeg({ optimiseScans: ... }) instead');
+
+/**
+ * Decorate the Sharp prototype with output-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    // Public
+    toFile,
+    toBuffer,
+    withMetadata,
+    jpeg,
+    png,
+    webp,
+    tiff,
+    raw,
+    toFormat,
+    tile,
+    // Private
+    _updateFormatOut,
+    _setBooleanOption,
+    _read,
+    _pipeline
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Deprecated
+  Sharp.prototype.quality = quality;
+  Sharp.prototype.progressive = progressive;
+  Sharp.prototype.compressionLevel = compressionLevel;
+  Sharp.prototype.withoutAdaptiveFiltering = withoutAdaptiveFiltering;
+  Sharp.prototype.withoutChromaSubsampling = withoutChromaSubsampling;
+  Sharp.prototype.trellisQuantisation = trellisQuantisation;
+  Sharp.prototype.trellisQuantization = trellisQuantisation;
+  Sharp.prototype.overshootDeringing = overshootDeringing;
+  Sharp.prototype.optimiseScans = optimiseScans;
+  Sharp.prototype.optimizeScans = optimiseScans;
+};

lib/resize.js

@@ -0,0 +1,301 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Weighting to apply to image crop.
+ * @member
+ * @private
+ */
+const gravity = {
+  center: 0,
+  centre: 0,
+  north: 1,
+  east: 2,
+  south: 3,
+  west: 4,
+  northeast: 5,
+  southeast: 6,
+  southwest: 7,
+  northwest: 8
+};
+
+/**
+ * Strategies for automagic crop behaviour.
+ * @member
+ * @private
+ */
+const strategy = {
+  entropy: 16,
+  attention: 17
+};
+
+/**
+ * Reduction kernels.
+ * @member
+ * @private
+ */
+const kernel = {
+  cubic: 'cubic',
+  lanczos2: 'lanczos2',
+  lanczos3: 'lanczos3'
+};
+
+/**
+ * Enlargement interpolators.
+ * @member
+ * @private
+ */
+const interpolator = {
+  nearest: 'nearest',
+  bilinear: 'bilinear',
+  bicubic: 'bicubic',
+  nohalo: 'nohalo',
+  lbb: 'lbb',
+  locallyBoundedBicubic: 'lbb',
+  vsqbs: 'vsqbs',
+  vertexSplitQuadraticBasisSpline: 'vsqbs'
+};
+
+/**
+ * Resize image to `width` x `height`.
+ * By default, the resized image is centre cropped to the exact size specified.
+ *
+ * Possible reduction kernels are:
+ * - `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
+ * - `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).
+ *
+ * Possible enlargement interpolators are:
+ * - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
+ * - `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
+ * - `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
+ * - `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
+ * - `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)" but typically reduces performance by a factor of 2.
+ * - `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
+ *
+ * @example
+ * sharp(inputBuffer)
+ *   .resize(200, 300, {
+ *     kernel: sharp.kernel.lanczos2,
+ *     interpolator: 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 lanczos2/nohalo scaled version, embedded on a white canvas,
+ *     // of the image data in inputBuffer
+ *   });
+ *
+ * @param {Number} [width] - pixels wide the resultant image should be, between 1 and 16383 (0x3FFF). Use `null` or `undefined` to auto-scale the width to match the height.
+ * @param {Number} [height] - pixels high the resultant image should be, between 1 and 16383. Use `null` or `undefined` to auto-scale the height to match the width.
+ * @param {Object} [options]
+ * @param {String} [options.kernel='lanczos3'] - the kernel to use for image reduction.
+ * @param {String} [options.interpolator='bicubic'] - the interpolator to use for image enlargement.
+ * @param {Boolean} [options.centreSampling=false] - use *magick centre sampling convention instead of corner sampling.
+ * @param {Boolean} [options.centerSampling=false] - alternative spelling of centreSampling.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const resize = function resize (width, height, options) {
+  if (is.defined(width)) {
+    if (is.integer(width) && is.inRange(width, 1, this.constructor.maximum.width)) {
+      this.options.width = width;
+    } else {
+      throw is.invalidParameterError('width', `integer between 1 and ${this.constructor.maximum.width}`, width);
+    }
+  } else {
+    this.options.width = -1;
+  }
+  if (is.defined(height)) {
+    if (is.integer(height) && is.inRange(height, 1, this.constructor.maximum.height)) {
+      this.options.height = height;
+    } else {
+      throw is.invalidParameterError('height', `integer between 1 and ${this.constructor.maximum.height}`, height);
+    }
+  } else {
+    this.options.height = -1;
+  }
+  if (is.object(options)) {
+    // 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);
+      }
+    }
+    // Interpolator
+    if (is.defined(options.interpolator)) {
+      if (is.string(interpolator[options.interpolator])) {
+        this.options.interpolator = interpolator[options.interpolator];
+      } else {
+        throw is.invalidParameterError('interpolator', 'valid interpolator name', options.interpolator);
+      }
+    }
+    // Centre sampling
+    options.centreSampling = is.bool(options.centerSampling) ? options.centerSampling : options.centreSampling;
+    if (is.defined(options.centreSampling)) {
+      this._setBooleanOption('centreSampling', options.centreSampling);
+    }
+  }
+  return this;
+};
+
+/**
+ * Crop the resized image to the exact size specified, the default behaviour.
+ *
+ * Possible attributes of the optional `sharp.gravity` are `north`, `northeast`, `east`, `southeast`, `south`,
+ * `southwest`, `west`, `northwest`, `center` and `centre`.
+ *
+ * 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.
+ *
+ * @example
+ * const transformer = sharp()
+ *   .resize(200, 200)
+ *   .crop(sharp.strategy.entropy)
+ *   .on('error', function(err) {
+ *     console.log(err);
+ *   });
+ * // Read image data from readableStream
+ * // Write 200px square auto-cropped image data to writableStream
+ * readableStream.pipe(transformer).pipe(writableStream);
+ *
+ * @param {String} [crop='centre'] - A member of `sharp.gravity` to crop to an edge/corner or `sharp.strategy` to crop dynamically.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const crop = function crop (crop) {
+  this.options.canvas = 'crop';
+  if (!is.defined(crop)) {
+    // Default
+    this.options.crop = gravity.center;
+  } else if (is.integer(crop) && is.inRange(crop, 0, 8)) {
+    // Gravity (numeric)
+    this.options.crop = crop;
+  } else if (is.string(crop) && is.integer(gravity[crop])) {
+    // Gravity (string)
+    this.options.crop = gravity[crop];
+  } else if (is.integer(crop) && crop >= strategy.entropy) {
+    // Strategy
+    this.options.crop = crop;
+  } else {
+    throw is.invalidParameterError('crop', 'valid crop id/name/strategy', crop);
+  }
+  return this;
+};
+
+/**
+ * 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.
+ *
+ * @example
+ * sharp('input.gif')
+ *   .resize(200, 300)
+ *   .background({r: 0, g: 0, b: 0, alpha: 0})
+ *   .embed()
+ *   .toFormat(sharp.format.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
+ *   });
+ *
+ * @returns {Sharp}
+ */
+const embed = function embed () {
+  this.options.canvas = 'embed';
+  return this;
+};
+
+/**
+ * Preserving aspect ratio, resize the image to be as large as possible
+ * while ensuring its dimensions are less than or equal to the `width` and `height` specified.
+ *
+ * Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
+ *
+ * @example
+ * sharp(inputBuffer)
+ *   .resize(200, 200)
+ *   .max()
+ *   .toFormat('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
+ *   });
+ *
+ * @returns {Sharp}
+ */
+const max = function max () {
+  this.options.canvas = 'max';
+  return this;
+};
+
+/**
+ * Preserving aspect ratio, resize the image to be as small as possible
+ * while ensuring its dimensions are greater than or equal to the `width` and `height` specified.
+ *
+ * Both `width` and `height` must be provided via `resize` otherwise the behaviour will default to `crop`.
+ *
+ * @returns {Sharp}
+ */
+const min = function min () {
+  this.options.canvas = 'min';
+  return this;
+};
+
+/**
+ * Ignoring the aspect ratio of the input, stretch the image to
+ * the exact `width` and/or `height` provided via `resize`.
+ * @returns {Sharp}
+ */
+const ignoreAspectRatio = function ignoreAspectRatio () {
+  this.options.canvas = 'ignore_aspect';
+  return this;
+};
+
+/**
+ * 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*".
+ * @param {Boolean} [withoutEnlargement=true]
+ * @returns {Sharp}
+*/
+const withoutEnlargement = function withoutEnlargement (withoutEnlargement) {
+  this.options.withoutEnlargement = is.bool(withoutEnlargement) ? withoutEnlargement : true;
+  return this;
+};
+
+/**
+ * Decorate the Sharp prototype with resize-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    resize,
+    crop,
+    embed,
+    max,
+    min,
+    ignoreAspectRatio,
+    withoutEnlargement
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.gravity = gravity;
+  Sharp.strategy = strategy;
+  Sharp.kernel = kernel;
+  Sharp.interpolator = interpolator;
+};

lib/utility.js

@@ -0,0 +1,116 @@
+'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 - 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}
+ */
+const cache = 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
+ */
+const 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}
+ */
+const counters = 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.
+ *
+ * This feature is currently off by default but future versions may reverse this.
+ * Versions of liborc prior to 0.4.25 are known to segfault under heavy load.
+ *
+ * @example
+ * const simd = sharp.simd();
+ * // simd is `true` if SIMD is currently enabled
+ * @example
+ * const simd = sharp.simd(true);
+ * // attempts to enable the use of SIMD, returning true if available
+ *
+ * @param {Boolean} [simd=false]
+ * @returns {Boolean}
+ */
+const simd = function simd (simd) {
+  return sharp.simd(is.bool(simd) ? simd : null);
+};
+simd(false);
+
+/**
+ * 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 +1,26 @@
+site_name: sharp
+site_url: http://sharp.dimens.io/
+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://dimens.io/">dimens.io</a>
+google_analytics: ['UA-13034748-12', 'sharp.dimens.io']
+theme: readthedocs
+markdown_extensions:
+  - toc:
+      permalink: True
+dev_addr: 0.0.0.0:10101
+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

@@ -1,17 +1,45 @@
 {
   "name": "sharp",
-  "version": "0.6.0",
+  "description": "High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP and TIFF images",
+  "version": "0.17.1",
   "author": "Lovell Fuller <npm@lovell.info>",
   "contributors": [
     "Pierre Inglebert <pierre.inglebert@gmail.com>",
     "Jonathan Ong <jonathanrichardong@gmail.com>",
-    "Chanon Sajjamanochai <chanon.s@gmail.com>"
+    "Chanon Sajjamanochai <chanon.s@gmail.com>",
+    "Juliano Julio <julianojulio@gmail.com>",
+    "Daniel Gasienica <daniel@gasienica.ch>",
+    "Julian Walker <julian@fiftythree.com>",
+    "Amit Pitaru <pitaru.amit@gmail.com>",
+    "Brandon Aaron <hello.brandon@aaron.sh>",
+    "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>"
   ],
-  "description": "High performance Node.js module to resize JPEG, PNG and WebP images using the libvips library",
   "scripts": {
-    "test": "node tests/unit && node tests/perf"
+    "clean": "rm -rf node_modules/ build/ vendor/ coverage/ test/fixtures/output.*",
+    "test": "semistandard && cross-env VIPS_WARNING=0 nyc --reporter=lcov --branches=99 mocha --slow=5000 --timeout=60000 ./test/unit/*.js",
+    "test-leak": "./test/leak/leak.sh",
+    "test-packaging": "./packaging/test-linux-x64.sh",
+    "docs": "for m in constructor input resize composite operation colour channel output utility; do documentation build --shallow --format=md lib/$m.js >docs/api-$m.md; done"
   },
-  "main": "index.js",
+  "main": "lib/index.js",
   "repository": {
     "type": "git",
     "url": "git://github.com/lovell/sharp"
@@ -22,30 +50,47 @@
     "webp",
     "tiff",
     "gif",
+    "svg",
+    "dzi",
+    "image",
     "resize",
     "thumbnail",
-    "sharpen",
     "crop",
-    "embed",
     "libvips",
-    "vips",
-    "fast",
-    "buffer",
-    "stream"
+    "vips"
   ],
   "dependencies": {
-    "nan": "^1.3.0",
-    "bluebird": "^2.3.0"
+    "caw": "^2.0.0",
+    "color": "^1.0.3",
+    "got": "^6.7.1",
+    "nan": "^2.5.0",
+    "semver": "^5.3.0",
+    "tar": "^2.2.1"
   },
   "devDependencies": {
-    "imagemagick": "^0.1.3",
-    "imagemagick-native": "^1.2.2",
-    "gm": "^1.16.0",
-    "async": "^0.9.0",
-    "benchmark": "^1.0.0"
+    "async": "^2.1.4",
+    "bufferutil": "^1.3.0",
+    "cross-env": "^3.1.4",
+    "documentation": "^4.0.0-beta.18",
+    "exif-reader": "^1.0.2",
+    "icc": "^1.0.0",
+    "mocha": "^3.2.0",
+    "node-cpplint": "^0.4.0",
+    "nyc": "^10.0.0",
+    "rimraf": "^2.5.4",
+    "semistandard": "^9.2.1",
+    "unzip": "^0.1.11"
+  },
+  "license": "Apache-2.0",
+  "config": {
+    "libvips": "8.4.2"
   },
-  "license": "Apache 2.0",
   "engines": {
-    "node": ">=0.10"
+    "node": ">=4"
+  },
+  "semistandard": {
+    "env": [
+      "mocha"
+    ]
   }
 }

packaging/README.md

@@ -0,0 +1,57 @@
+# Packaging scripts
+
+libvips and its dependencies are provided as pre-compiled shared libraries
+for the most common operating systems and CPU architectures.
+
+During `npm install`, these binaries are fetched as tarballs from
+[Bintray](https://dl.bintray.com/lovell/sharp/) via HTTPS
+and stored locally within `node_modules/sharp`.
+
+## Using a custom tarball
+
+A custom tarball stored on the local filesystem can be used instead.
+Place it in the following location, where `x.y.z` is the libvips version,
+`platform` is the value of `process.platform` and
+`arch` is the value of `process.arch` (plus the version number for ARM).
+
+`node_modules/sharp/packaging/libvips-x.y.z-platform-arch.tar.gz`
+
+For example, for libvips v8.3.3 on an ARMv6 Linux machine, use:
+
+`node_modules/sharp/packaging/libvips-8.3.3-linux-armv6.tar.gz`
+
+Remove any `sharp/lib` and `sharp/include` directories
+before running `npm install` again.
+
+## Creating a tarball
+
+Most people will not need to do this; proceed with caution.
+
+The `packaging` directory contains the top-level [build script](build.sh).
+
+### Linux
+
+One [build script](build/lin.sh) is used to (cross-)compile
+the same shared libraries within multiple containers.
+
+* [x64](linux-x64/Dockerfile)
+* [ARMv6](linux-armv6/Dockerfile)
+* [ARMv7-A](linux-armv7/Dockerfile)
+* [ARMv8-A](linux-armv8/Dockerfile)
+
+The QEMU user mode emulation binaries are required to build for
+the ARMv6 platform as the Debian armhf cross-compiler erroneously
+generates unsupported Thumb 2 instructions.
+
+```sh
+sudo apt-get install qemu-user-static
+```
+
+### Windows
+
+The output of libvips' [build-win64](https://github.com/jcupitt/build-win64)
+"web" target is [post-processed](build/win.sh) within a [container](win32-x64/Dockerfile).
+
+### OS X
+
+See [package-libvips-darwin](https://github.com/lovell/package-libvips-darwin).

packaging/build.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+set -e
+
+if [ $# -lt 1 ]; then
+  echo
+  echo "Usage: $0 VERSION [PLATFORM]"
+  echo "Build shared libraries for libvips and its dependencies via containers"
+  echo
+  echo "Please specify the libvips VERSION, e.g. 8.3.3"
+  echo
+  echo "Optionally build for only one PLATFORM, defaults to building for all"
+  echo "Possible values for PLATFORM are: win32-x64, linux-x64, linux-armv6,"
+  echo "linux-armv7, linux-armv8"
+  echo
+  exit 1
+fi
+VERSION_VIPS="$1"
+PLATFORM="${2:-all}"
+
+# Is docker available?
+if ! type docker >/dev/null; then
+  echo "Please install docker"
+  exit 1
+fi
+
+# Windows (x64)
+if [ $PLATFORM = "all" ] || [ $PLATFORM = "win32-x64" ]; then
+  echo "Building win32-x64..."
+  docker build -t vips-dev-win32-x64 win32-x64
+  docker run --rm -e "VERSION_VIPS=${VERSION_VIPS}" -v $PWD:/packaging vips-dev-win32-x64 sh -c "/packaging/build/win.sh"
+fi
+
+# Linux (x64, ARMv6, ARMv7, ARMv8)
+for flavour in linux-x64 linux-armv6 linux-armv7 linux-armv8; do
+  if [ $PLATFORM = "all" ] || [ $PLATFORM = $flavour ]; then
+    echo "Building $flavour..."
+    docker build -t vips-dev-$flavour $flavour
+    docker run --rm -e "VERSION_VIPS=${VERSION_VIPS}" -v $PWD:/packaging vips-dev-$flavour sh -c "/packaging/build/lin.sh"
+  fi
+done
+
+# Display checksums
+sha256sum *.tar.gz

packaging/build/lin.sh

@@ -0,0 +1,239 @@
+#!/bin/sh
+set -e
+
+# Working directories
+DEPS=/deps
+TARGET=/target
+mkdir ${DEPS}
+mkdir ${TARGET}
+
+# Common build paths and flags
+export PKG_CONFIG_PATH="${PKG_CONFIG_PATH}:${TARGET}/lib/pkgconfig"
+export PATH="${PATH}:${TARGET}/bin"
+export CPPFLAGS="-I${TARGET}/include"
+export LDFLAGS="-L${TARGET}/lib"
+export CFLAGS="${FLAGS}"
+export CXXFLAGS="${FLAGS}"
+
+# Dependency version numbers
+VERSION_ZLIB=1.2.10
+VERSION_FFI=3.2.1
+VERSION_GLIB=2.50.1
+VERSION_XML2=2.9.4
+VERSION_GSF=1.14.40
+VERSION_EXIF=0.6.21
+VERSION_LCMS2=2.8
+VERSION_JPEG=1.5.1
+VERSION_PNG16=1.6.28
+VERSION_WEBP=0.5.1
+VERSION_TIFF=4.0.6
+VERSION_ORC=0.4.26
+VERSION_GDKPIXBUF=2.36.0
+VERSION_FREETYPE=2.7
+VERSION_FONTCONFIG=2.12.1
+VERSION_HARFBUZZ=1.3.2
+VERSION_PIXMAN=0.34.0
+VERSION_CAIRO=1.14.6
+VERSION_PANGO=1.40.3
+VERSION_CROCO=0.6.11
+VERSION_SVG=2.40.16
+VERSION_GIF=5.1.4
+
+# Least out-of-sync Sourceforge mirror
+SOURCEFORGE_MIRROR=netix
+
+mkdir ${DEPS}/zlib
+curl -Ls http://zlib.net/zlib-${VERSION_ZLIB}.tar.xz | tar xJC ${DEPS}/zlib --strip-components=1
+cd ${DEPS}/zlib
+./configure --prefix=${TARGET} --uname=linux
+make install
+rm ${TARGET}/lib/libz.a
+
+mkdir ${DEPS}/ffi
+curl -Ls ftp://sourceware.org/pub/libffi/libffi-${VERSION_FFI}.tar.gz | tar xzC ${DEPS}/ffi --strip-components=1
+cd ${DEPS}/ffi
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-builddir
+make install-strip
+
+mkdir ${DEPS}/glib
+curl -Ls https://download.gnome.org/sources/glib/2.50/glib-${VERSION_GLIB}.tar.xz | tar xJC ${DEPS}/glib --strip-components=1
+cd ${DEPS}/glib
+echo glib_cv_stack_grows=no >>glib.cache
+echo glib_cv_uscore=no >>glib.cache
+./configure --cache-file=glib.cache --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --with-pcre=internal --disable-libmount
+make install-strip
+
+mkdir ${DEPS}/xml2
+curl -Ls http://xmlsoft.org/sources/libxml2-${VERSION_XML2}.tar.gz | tar xzC ${DEPS}/xml2 --strip-components=1
+cd ${DEPS}/xml2
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking \
+  --without-python --without-debug --without-docbook --without-ftp --without-html --without-legacy \
+  --without-pattern --without-push --without-regexps --without-schemas --without-schematron --with-zlib=${TARGET}
+make install-strip
+
+mkdir ${DEPS}/gsf
+curl -Ls https://download.gnome.org/sources/libgsf/1.14/libgsf-${VERSION_GSF}.tar.xz | tar xJC ${DEPS}/gsf --strip-components=1
+cd ${DEPS}/gsf
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/exif
+curl -Ls http://${SOURCEFORGE_MIRROR}.dl.sourceforge.net/project/libexif/libexif/${VERSION_EXIF}/libexif-${VERSION_EXIF}.tar.bz2 | tar xjC ${DEPS}/exif --strip-components=1
+cd ${DEPS}/exif
+autoreconf -fiv
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/lcms2
+curl -Ls http://${SOURCEFORGE_MIRROR}.dl.sourceforge.net/project/lcms/lcms/${VERSION_LCMS2}/lcms2-${VERSION_LCMS2}.tar.gz | tar xzC ${DEPS}/lcms2 --strip-components=1
+cd ${DEPS}/lcms2
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/jpeg
+curl -Ls https://github.com/libjpeg-turbo/libjpeg-turbo/archive/${VERSION_JPEG}.tar.gz | tar xzC ${DEPS}/jpeg --strip-components=1
+cd ${DEPS}/jpeg
+autoreconf -fiv
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --with-jpeg8 --without-turbojpeg
+make install-strip
+
+mkdir ${DEPS}/png16
+curl -Ls http://${SOURCEFORGE_MIRROR}.dl.sourceforge.net/project/libpng/libpng16/${VERSION_PNG16}/libpng-${VERSION_PNG16}.tar.xz | tar xJC ${DEPS}/png16 --strip-components=1
+cd ${DEPS}/png16
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/webp
+curl -Ls http://downloads.webmproject.org/releases/webp/libwebp-${VERSION_WEBP}.tar.gz | tar xzC ${DEPS}/webp --strip-components=1
+cd ${DEPS}/webp
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-neon
+make install-strip
+
+mkdir ${DEPS}/tiff
+curl -Ls http://download.osgeo.org/libtiff/tiff-${VERSION_TIFF}.tar.gz | tar xzC ${DEPS}/tiff --strip-components=1
+cd ${DEPS}/tiff
+# Apply patches for various libtiff security vulnerabilities reported since v4.0.6
+VERSION_TIFF_GIT_MASTER_SHA=$(curl -Ls https://api.github.com/repos/vadz/libtiff/git/refs/heads/master | jq -r '.object.sha' | head -c7)
+curl -Ls https://github.com/vadz/libtiff/compare/Release-v4-0-6...master.patch | patch -p1 -t || true
+if [ -n "${CHOST}" ]; then autoreconf -fiv; fi
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-mdi --disable-pixarlog --disable-cxx
+make install-strip
+
+mkdir ${DEPS}/orc
+curl -Ls http://gstreamer.freedesktop.org/data/src/orc/orc-${VERSION_ORC}.tar.xz | tar xJC ${DEPS}/orc --strip-components=1
+cd ${DEPS}/orc
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+cd ${TARGET}/lib
+rm -rf liborc-test-*
+
+mkdir ${DEPS}/gdkpixbuf
+curl -Ls https://download.gnome.org/sources/gdk-pixbuf/2.36/gdk-pixbuf-${VERSION_GDKPIXBUF}.tar.xz | tar xJC ${DEPS}/gdkpixbuf --strip-components=1
+cd ${DEPS}/gdkpixbuf
+LD_LIBRARY_PATH=${TARGET}/lib \
+./configure --cache-file=gdkpixbuf.cache --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-introspection --disable-modules --disable-gio-sniffing --without-libtiff --without-gdiplus --with-included-loaders=png,jpeg
+make install-strip
+
+mkdir ${DEPS}/freetype
+curl -Ls http://${SOURCEFORGE_MIRROR}.dl.sourceforge.net/project/freetype/freetype2/${VERSION_FREETYPE}/freetype-${VERSION_FREETYPE}.tar.gz | tar xzC ${DEPS}/freetype --strip-components=1
+cd ${DEPS}/freetype
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static
+make install
+
+mkdir ${DEPS}/fontconfig
+curl -Ls https://www.freedesktop.org/software/fontconfig/release/fontconfig-${VERSION_FONTCONFIG}.tar.bz2 | tar xjC ${DEPS}/fontconfig --strip-components=1
+cd ${DEPS}/fontconfig
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --enable-libxml2 --sysconfdir=/etc
+make install-strip
+
+mkdir ${DEPS}/harfbuzz
+curl -Ls https://www.freedesktop.org/software/harfbuzz/release/harfbuzz-${VERSION_HARFBUZZ}.tar.bz2 | tar xjC ${DEPS}/harfbuzz --strip-components=1
+cd ${DEPS}/harfbuzz
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/pixman
+curl -Ls http://cairographics.org/releases/pixman-${VERSION_PIXMAN}.tar.gz | tar xzC ${DEPS}/pixman --strip-components=1
+cd ${DEPS}/pixman
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-libpng --disable-arm-iwmmxt
+make install-strip
+
+mkdir ${DEPS}/cairo
+curl -Ls http://cairographics.org/releases/cairo-${VERSION_CAIRO}.tar.xz | tar xJC ${DEPS}/cairo --strip-components=1
+cd ${DEPS}/cairo
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking \
+  --disable-xlib --disable-xcb --disable-quartz --disable-win32 --disable-egl --disable-glx --disable-wgl \
+  --disable-script --disable-ps --disable-gobject --disable-trace --disable-interpreter
+make install-strip
+
+mkdir ${DEPS}/pango
+curl -Ls https://download.gnome.org/sources/pango/1.40/pango-${VERSION_PANGO}.tar.xz | tar xJC ${DEPS}/pango --strip-components=1
+cd ${DEPS}/pango
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/croco
+curl -Ls https://download.gnome.org/sources/libcroco/0.6/libcroco-${VERSION_CROCO}.tar.xz | tar xJC ${DEPS}/croco --strip-components=1
+cd ${DEPS}/croco
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/svg
+curl -Ls https://download.gnome.org/sources/librsvg/2.40/librsvg-${VERSION_SVG}.tar.xz | tar xJC ${DEPS}/svg --strip-components=1
+cd ${DEPS}/svg
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking --disable-introspection --disable-tools --disable-pixbuf-loader
+make install-strip
+
+mkdir ${DEPS}/gif
+curl -Ls http://${SOURCEFORGE_MIRROR}.dl.sourceforge.net/project/giflib/giflib-${VERSION_GIF}.tar.gz | tar xzC ${DEPS}/gif --strip-components=1
+cd ${DEPS}/gif
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking
+make install-strip
+
+mkdir ${DEPS}/vips
+curl -Ls http://www.vips.ecs.soton.ac.uk/supported/8.4/vips-${VERSION_VIPS}.tar.gz | tar xzC ${DEPS}/vips --strip-components=1
+cd ${DEPS}/vips
+./configure --host=${CHOST} --prefix=${TARGET} --enable-shared --disable-static --disable-dependency-tracking \
+  --disable-debug --disable-introspection --without-python --without-fftw \
+  --without-magick --without-pangoft2 --without-ppm --without-analyze --without-radiance \
+  --with-zip-includes=${TARGET}/include --with-zip-libraries=${TARGET}/lib \
+  --with-jpeg-includes=${TARGET}/include --with-jpeg-libraries=${TARGET}/lib
+make install-strip
+
+# Remove the old C++ bindings
+cd ${TARGET}/include
+rm -rf vips/vipsc++.h vips/vipscpp.h
+cd ${TARGET}/lib
+rm -rf pkgconfig .libs *.la libvipsCC*
+
+# Create JSON file of version numbers
+cd ${TARGET}
+echo "{\n\
+  \"cairo\": \"${VERSION_CAIRO}\",\n\
+  \"croco\": \"${VERSION_CROCO}\",\n\
+  \"exif\": \"${VERSION_EXIF}\",\n\
+  \"ffi\": \"${VERSION_FFI}\",\n\
+  \"fontconfig\": \"${VERSION_FONTCONFIG}\",\n\
+  \"freetype\": \"${VERSION_FREETYPE}\",\n\
+  \"gdkpixbuf\": \"${VERSION_GDKPIXBUF}\",\n\
+  \"gif\": \"${VERSION_GIF}\",\n\
+  \"glib\": \"${VERSION_GLIB}\",\n\
+  \"gsf\": \"${VERSION_GSF}\",\n\
+  \"harfbuzz\": \"${VERSION_HARFBUZZ}\",\n\
+  \"jpeg\": \"${VERSION_JPEG}\",\n\
+  \"lcms\": \"${VERSION_LCMS2}\",\n\
+  \"orc\": \"${VERSION_ORC}\",\n\
+  \"pango\": \"${VERSION_PANGO}\",\n\
+  \"pixman\": \"${VERSION_PIXMAN}\",\n\
+  \"png\": \"${VERSION_PNG16}\",\n\
+  \"svg\": \"${VERSION_SVG}\",\n\
+  \"tiff\": \"${VERSION_TIFF}-${VERSION_TIFF_GIT_MASTER_SHA}\",\n\
+  \"vips\": \"${VERSION_VIPS}\",\n\
+  \"webp\": \"${VERSION_WEBP}\",\n\
+  \"xml\": \"${VERSION_XML2}\",\n\
+  \"zlib\": \"${VERSION_ZLIB}\"\n\
+}" >lib/versions.json
+
+# Create .tar.gz
+tar czf /packaging/libvips-${VERSION_VIPS}-${PLATFORM}.tar.gz include lib
+advdef --recompress --shrink-insane /packaging/libvips-${VERSION_VIPS}-${PLATFORM}.tar.gz

packaging/build/win.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+set -e
+
+# Fetch and unzip
+mkdir /vips
+cd /vips
+curl -L -O https://github.com/lovell/build-win64/releases/download/v${VERSION_VIPS}/vips-dev-w64-web-${VERSION_VIPS}.zip
+unzip vips-dev-w64-web-${VERSION_VIPS}.zip
+
+# Clean and zip
+cd /vips/vips-dev-8.4
+rm bin/libvipsCC-42.dll bin/libvips-cpp-42.dll bin/libgsf-win32-1-114.dll
+cp bin/*.dll lib/
+cp -r lib64/* lib/
+
+# Temp patch for __declspec ordering
+curl -L -o include/vips/VImage8.h https://raw.githubusercontent.com/lovell/libvips/e1aef0445bf123d2de000bc7f2ef97b9f788eea0/cplusplus/include/vips/VImage8.h
+
+echo "Creating tarball"
+tar czf /packaging/libvips-${VERSION_VIPS}-${PLATFORM}.tar.gz include lib/glib-2.0 lib/libvips.lib lib/libglib-2.0.lib lib/libgobject-2.0.lib lib/*.dll
+echo "Shrinking tarball"
+advdef --recompress --shrink-insane /packaging/libvips-${VERSION_VIPS}-${PLATFORM}.tar.gz

packaging/linux-armv6/Dockerfile

@@ -0,0 +1,15 @@
+FROM socialdefect/raspbian-jessie-core
+MAINTAINER Lovell Fuller <npm@lovell.info>
+
+# Create Rasbian-based container suitable for compiling Linux ARMv6 binaries
+# Requires the QEMU user mode emulation binaries on the host machine
+
+# Build dependencies
+RUN \
+  apt-get update && \
+  apt-get install -y build-essential curl autoconf libtool nasm gtk-doc-tools texinfo advancecomp libglib2.0-dev jq
+
+# Compiler settings
+ENV \
+  PLATFORM=linux-armv6 \
+  FLAGS="-Os"

packaging/linux-armv7/Dockerfile

@@ -0,0 +1,20 @@
+FROM debian:jessie
+MAINTAINER Lovell Fuller <npm@lovell.info>
+
+# Create Debian-based container suitable for cross-compiling Linux ARMv7-A binaries
+
+# Build dependencies
+RUN \
+  apt-get update && \
+  apt-get install -y curl && \
+  echo "deb http://emdebian.org/tools/debian/ jessie main" | tee /etc/apt/sources.list.d/crosstools.list && \
+  curl http://emdebian.org/tools/debian/emdebian-toolchain-archive.key | apt-key add - && \
+  dpkg --add-architecture armhf && \
+  apt-get update && \
+  apt-get install -y crossbuild-essential-armhf autoconf libtool nasm gtk-doc-tools texinfo advancecomp libglib2.0-dev jq
+
+# Compiler settings
+ENV \
+  PLATFORM=linux-armv7 \
+  CHOST=arm-linux-gnueabihf \
+  FLAGS="-marm -march=armv7-a -mfpu=neon-vfpv4 -mfloat-abi=hard -Os"

packaging/linux-armv8/Dockerfile

@@ -0,0 +1,18 @@
+FROM debian:stretch
+MAINTAINER Lovell Fuller <npm@lovell.info>
+
+# Create Debian-based container suitable for cross-compiling Linux ARMv8-A binaries
+
+# Build dependencies
+RUN \
+  apt-get update && \
+  apt-get install -y curl && \
+  dpkg --add-architecture arm64 && \
+  apt-get update && \
+  apt-get install -y crossbuild-essential-arm64 autoconf libtool nasm gtk-doc-tools texinfo advancecomp libglib2.0-dev jq
+
+# Compiler settings
+ENV \
+  PLATFORM=linux-armv8 \
+  CHOST=aarch64-linux-gnu \
+  FLAGS="-march=armv8-a -Os"

packaging/linux-x64/Dockerfile

@@ -0,0 +1,16 @@
+FROM debian:wheezy
+MAINTAINER Lovell Fuller <npm@lovell.info>
+
+# Create Debian-based container suitable for building Linux x64 binaries
+
+# Build dependencies
+RUN \
+  echo "deb http://ftp.debian.org/debian wheezy-backports main" | tee /etc/apt/sources.list.d/wheezy-backports.list && \
+  apt-get update && \
+  apt-get install -y build-essential autoconf libtool nasm gtk-doc-tools texinfo advancecomp && \
+  apt-get -t wheezy-backports install -y jq
+
+# Compiler settings
+ENV \
+  PLATFORM="linux-x64" \
+  FLAGS="-O3"

packaging/test-linux-arm.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 IP"
+  echo "Test sharp on ARM using Docker, where IP is"
+  echo "the address of a Raspberry Pi running HypriotOS"
+  exit 1
+fi
+IP="$1"
+
+echo "Verifying connectivity to $IP"
+if ! ping -c 1 $IP; then
+  echo "Could not connect to $IP"
+  exit 1
+fi
+
+if ! type sshpass >/dev/null; then
+  echo "Please install sshpass"
+  exit 1
+fi
+
+export SSHPASS=hypriot
+
+echo "Copying sharp source to device"
+sshpass -e scp -o PreferredAuthentications=password -r ../../sharp pirate@${IP}:/home/pirate/sharp
+
+echo "Compile and test within container"
+sshpass -e ssh -o PreferredAuthentications=password -t pirate@${IP} "docker run --rm -v \${PWD}/sharp:/s hypriot/rpi-node:6 sh -c 'cd /s && npm install --unsafe-perm && npm test'"

packaging/test-linux-x64.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+# Verify docker is available
+if ! type docker >/dev/null; then
+  echo "Please install docker"
+  exit 1
+fi
+
+version_node=6.3.0
+
+test="npm run clean; npm install --unsafe-perm; npm test"
+
+# Debian 7, 8
+# Ubuntu 14.04
+for dist in wheezy jessie trusty; do
+  echo "Testing $dist..."
+  if docker run -i -t --rm -v $PWD:/v -e "NODE_ENV=development" nodesource/$dist:$version_node >packaging/$dist.log 2>&1 sh -c "cd /v; ./packaging/test/debian.sh; $test";
+  then echo "$dist OK"
+  else echo "$dist fail" && cat packaging/$dist.log
+  fi
+done
+
+# Centos 7
+echo "Testing centos7..."
+if docker run -i -t --rm -v $PWD:/v -e "NODE_ENV=development" nodesource/centos7:$version_node >packaging/$dist.log 2>&1 sh -c "cd /v; $test";
+then echo "centos7 OK"
+else echo "centos7 fail" && cat packaging/$dist.log
+fi
+
+# Fedora 22
+echo "Testing fedora22..."
+if docker run -i -t --rm -v $PWD:/v -e "NODE_ENV=development" nodesource/fedora22:$version_node >packaging/$dist.log 2>&1 sh -c "cd /v; $test";
+then echo "fedora22 OK"
+else echo "fedora22 fail" && cat packaging/$dist.log
+fi
+
+# openSUSE 13.2
+echo "Testing opensuse..."
+if docker run -i -t --rm -v $PWD:/v opensuse:13.2 >packaging/opensuse.log 2>&1 /bin/sh -c "cd /v; ./packaging/test/opensuse.sh; $test";
+then echo "opensuse OK"
+else echo "opensuse fail" && cat packaging/opensuse.log
+fi
+
+# Archlinux 2015.06.01
+echo "Testing archlinux..."
+if docker run -i -t --rm -v $PWD:/v pritunl/archlinux:latest >packaging/archlinux.log 2>&1 sh -c "cd /v; ./packaging/test/archlinux.sh; $test";
+then echo "archlinux OK"
+else echo "archlinux fail" && cat packaging/archlinux.log
+fi
+
+# Alpine
+echo "Testing alpine..."
+if docker run -i -t --rm -v $PWD:/v -e "SHARP_TEST_WITHOUT_CACHE=0" alpine:edge >packaging/alpine.log 2>&1 sh -c "cd /v; ./packaging/test/alpine.sh; $test";
+then echo "alpine OK"
+else echo "alpine fail" && cat packaging/alpine.log
+fi

packaging/test/alpine.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# Install build dependencies
+apk add --update make gcc g++ python nodejs
+
+# Install libvips from aports/testing
+apk add --update --repository http://dl-cdn.alpinelinux.org/alpine/edge/testing vips-dev

packaging/test/archlinux.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+# Install Node.js on Archlinux
+pacman -Sy --noconfirm gcc make python2 nodejs npm | cat
+ln -s /usr/bin/python2 /usr/bin/python

packaging/test/debian.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+# Install pkg-config on Debian/Ubuntu
+apt-get update
+apt-get install -y pkg-config

packaging/test/opensuse.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# Install Node.js on openSUSE 13.2
+zypper addrepo http://download.opensuse.org/repositories/devel:languages:nodejs/openSUSE_13.2/devel:languages:nodejs.repo
+zypper --gpg-auto-import-keys refresh
+zypper --non-interactive install gcc-c++ make nodejs-devel npm
+npm install -g npm

packaging/win32-x64/Dockerfile

@@ -0,0 +1,8 @@
+FROM debian:jessie
+MAINTAINER Lovell Fuller <npm@lovell.info>
+
+# Create Debian-based container suitable for post-processing Windows x64 binaries
+
+RUN apt-get update && apt-get install -y curl zip advancecomp
+
+ENV PLATFORM=win32-x64

src/common.cc

@@ -0,0 +1,453 @@
+#include <cstdlib>
+#include <string>
+#include <string.h>
+
+#include <node.h>
+#include <node_buffer.h>
+#include <vips/vips8>
+
+#include "nan.h"
+#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());
+  }
+
+  // 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 {
+      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);
+    }
+    // Density for vector-based input
+    if (HasAttr(input, "density")) {
+      descriptor->density = AttrTo<uint32_t>(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");
+    }
+    return descriptor;
+  }
+
+  // How many tasks are in the queue?
+  volatile int counterQueue = 0;
+
+  // How many tasks are being processed?
+  volatile int counterProcess = 0;
+
+  // Filename extension checkers
+  static bool EndsWith(std::string const &str, std::string const &end) {
+    return str.length() >= end.length() && 0 == str.compare(str.length() - end.length(), end.length(), end);
+  }
+  bool IsJpeg(std::string const &str) {
+    return EndsWith(str, ".jpg") || EndsWith(str, ".jpeg") || EndsWith(str, ".JPG") || EndsWith(str, ".JPEG");
+  }
+  bool IsPng(std::string const &str) {
+    return EndsWith(str, ".png") || EndsWith(str, ".PNG");
+  }
+  bool IsWebp(std::string const &str) {
+    return EndsWith(str, ".webp") || EndsWith(str, ".WEBP");
+  }
+  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");
+  }
+
+  /*
+    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;
+    }
+    return id;
+  }
+
+  /*
+    Determine image format of a buffer.
+  */
+  ImageType DetermineImageType(void *buffer, size_t const length) {
+    ImageType imageType = ImageType::UNKNOWN;
+    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 (EndsWith(loader, "PngBuffer")) {
+        imageType = ImageType::PNG;
+      } else if (EndsWith(loader, "WebpBuffer")) {
+        imageType = ImageType::WEBP;
+      } 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;
+  }
+
+  /*
+    Determine image format, reads the first few bytes of the file
+  */
+  ImageType DetermineImageType(char const *file) {
+    ImageType imageType = ImageType::UNKNOWN;
+    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;
+      }
+    }
+    return imageType;
+  }
+
+  /*
+    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) {
+      // From buffer
+      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);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+              option->set("dpi", static_cast<double>(descriptor->density));
+            }
+            if (imageType == ImageType::MAGICK) {
+              option->set("density", std::to_string(descriptor->density).data());
+            }
+            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 (...) {
+            throw vips::VError("Input buffer has corrupt header");
+          }
+        } else {
+          throw vips::VError("Input buffer contains unsupported image format");
+        }
+      }
+    } else {
+      // From filesystem
+      imageType = DetermineImageType(descriptor->file.data());
+      if (imageType != ImageType::UNKNOWN) {
+        try {
+          vips::VOption *option = VImage::option()->set("access", accessMethod);
+          if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+            option->set("dpi", static_cast<double>(descriptor->density));
+          }
+          if (imageType == ImageType::MAGICK) {
+            option->set("density", std::to_string(descriptor->density).data());
+          }
+          image = VImage::new_from_file(descriptor->file.data(), option);
+          if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
+            SetDensity(image, descriptor->density);
+          }
+        } catch (...) {
+          throw vips::VError("Input file has corrupt header");
+        }
+      } else {
+        throw vips::VError("Input file is missing or of an unsupported image format");
+      }
+    }
+    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(VImage image) {
+    int const bands = image.bands();
+    VipsInterpretation const interpretation = image.interpretation();
+    return (
+      (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(VImage image) {
+    int orientation = 0;
+    if (image.get_typeof(VIPS_META_ORIENTATION) != 0) {
+      orientation = image.get_int(VIPS_META_ORIENTATION);
+    }
+    return orientation;
+  }
+
+  /*
+    Set EXIF Orientation of image.
+  */
+  void SetExifOrientation(VImage image, int const orientation) {
+    image.set(VIPS_META_ORIENTATION, orientation);
+  }
+
+  /*
+    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 int density) {
+    const double pixelsPerMm = static_cast<double>(density) / 25.4;
+    image.set("Xres", pixelsPerMm);
+    image.set("Yres", pixelsPerMm);
+    image.set(VIPS_META_RESOLUTION_UNIT, "in");
+  }
+
+  /*
+    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);
+    }
+  }
+
+  /*
+    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;
+      case 5:
+        // Northeast
+        left = inWidth - outWidth;
+        break;
+      case 6:
+        // Southeast
+        left = inWidth - outWidth;
+        top = inHeight - outHeight;
+      case 7:
+        // Southwest
+        top = inHeight - outHeight;
+      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);
+    }
+  }
+
+}  // namespace sharp

src/common.h

@@ -0,0 +1,209 @@
+#ifndef SRC_COMMON_H_
+#define SRC_COMMON_H_
+
+#include <string>
+#include <tuple>
+
+#include <node.h>
+#include <vips/vips8>
+
+#include "nan.h"
+
+// Verify platform and compiler compatibility
+
+#if (VIPS_MAJOR_VERSION < 8 || (VIPS_MAJOR_VERSION == 8 && VIPS_MINOR_VERSION < 4))
+#error libvips version 8.4.x required - see sharp.dimens.io/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.dimens.io/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.dimens.io/page/install#prerequisites
+#endif
+#endif
+
+using vips::VImage;
+
+namespace sharp {
+
+  struct InputDescriptor {
+    std::string name;
+    std::string file;
+    char *buffer;
+    size_t bufferLength;
+    int density;
+    int rawChannels;
+    int rawWidth;
+    int rawHeight;
+
+    InputDescriptor():
+      buffer(nullptr),
+      bufferLength(0),
+      density(72),
+      rawChannels(0),
+      rawWidth(0),
+      rawHeight(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);
+  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 {
+    JPEG,
+    PNG,
+    WEBP,
+    TIFF,
+    GIF,
+    SVG,
+    PDF,
+    MAGICK,
+    OPENSLIDE,
+    PPM,
+    FITS,
+    VIPS,
+    RAW,
+    UNKNOWN
+  };
+
+  // How many tasks are in the queue?
+  extern volatile int counterQueue;
+
+  // How many tasks are being processed?
+  extern volatile int counterProcess;
+
+  // Filename extension checkers
+  bool IsJpeg(std::string const &str);
+  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.
+  */
+  ImageType DetermineImageType(void *buffer, size_t const length);
+
+  /*
+    Determine image format of a file.
+  */
+  ImageType DetermineImageType(char const *file);
+
+  /*
+    Open an image from the given InputDescriptor (filesystem, compressed buffer, raw pixel data)
+  */
+  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(VImage image);
+
+  /*
+    Get EXIF Orientation of image, if any.
+  */
+  int ExifOrientation(VImage image);
+
+  /*
+    Set EXIF Orientation of image.
+  */
+  void SetExifOrientation(VImage image, int const orientation);
+
+  /*
+    Remove EXIF Orientation from image.
+  */
+  void RemoveExifOrientation(VImage image);
+
+  /*
+    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 int density);
+
+  /*
+    Called when a Buffer undergoes GC, required to support mixed runtime libraries in Windows
+  */
+  void FreeCallback(char* data, void* hint);
+
+  /*
+    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);
+
+}  // 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

@@ -0,0 +1,153 @@
+#include <numeric>
+
+#include <node.h>
+#include <vips/vips8>
+
+#include "nan.h"
+#include "common.h"
+#include "metadata.h"
+
+class MetadataWorker : public Nan::AsyncWorker {
+ public:
+  MetadataWorker(
+    Nan::Callback *callback, MetadataBaton *baton,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist
+  ) : Nan::AsyncWorker(callback), baton(baton), 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(&sharp::counterQueue);
+
+    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 (imageType != sharp::ImageType::UNKNOWN) {
+      // Image type
+      baton->format = sharp::ImageTypeId(imageType);
+      // VipsImage attributes
+      baton->width = image.width();
+      baton->height = image.height();
+      baton->space = vips_enum_nick(VIPS_TYPE_INTERPRETATION, image.interpretation());
+      baton->channels = image.bands();
+      if (sharp::HasDensity(image)) {
+        baton->density = sharp::GetDensity(image);
+      }
+      baton->hasProfile = sharp::HasProfile(image);
+      // Derived attributes
+      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;
+      }
+    }
+
+    // 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 {
+      // Metadata Object
+      v8::Local<v8::Object> info = New<v8::Object>();
+      Set(info, New("format").ToLocalChecked(), New<v8::String>(baton->format).ToLocalChecked());
+      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));
+      if (baton->density > 0) {
+        Set(info, New("density").ToLocalChecked(), New<v8::Uint32>(baton->density));
+      }
+      Set(info, New("hasProfile").ToLocalChecked(), New<v8::Boolean>(baton->hasProfile));
+      Set(info, New("hasAlpha").ToLocalChecked(), New<v8::Boolean>(baton->hasAlpha));
+      if (baton->orientation > 0) {
+        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()
+        );
+      }
+      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;
+
+    // Return to JavaScript
+    callback->Call(2, argv);
+  }
+
+ private:
+  MetadataBaton* baton;
+  std::vector<v8::Local<v8::Object>> buffersToPersist;
+};
+
+/*
+  metadata(options, callback)
+*/
+NAN_METHOD(metadata) {
+  // 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;
+  v8::Local<v8::Object> options = info[0].As<v8::Object>();
+
+  // Input
+  baton->input = sharp::CreateInputDescriptor(sharp::AttrAs<v8::Object>(options, "input"), buffersToPersist);
+
+  // Join queue for worker thread
+  Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
+  Nan::AsyncQueueWorker(new MetadataWorker(callback, baton, buffersToPersist));
+
+  // Increment queued task counter
+  g_atomic_int_inc(&sharp::counterQueue);
+}

src/metadata.h

@@ -0,0 +1,43 @@
+#ifndef SRC_METADATA_H_
+#define SRC_METADATA_H_
+
+#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;
+  int density;
+  bool hasProfile;
+  bool hasAlpha;
+  int orientation;
+  char *exif;
+  size_t exifLength;
+  char *icc;
+  size_t iccLength;
+  std::string err;
+
+  MetadataBaton():
+    input(nullptr),
+    width(0),
+    height(0),
+    channels(0),
+    density(0),
+    hasProfile(false),
+    hasAlpha(false),
+    orientation(0),
+    exif(nullptr),
+    exifLength(0),
+    icc(nullptr),
+    iccLength(0) {}
+};
+
+NAN_METHOD(metadata);
+
+#endif  // SRC_METADATA_H_

src/operations.cc

@@ -0,0 +1,496 @@
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vips/vips8>
+
+#include "common.h"
+#include "operations.h"
+
+using vips::VImage;
+using vips::VError;
+
+namespace sharp {
+
+  /*
+    Alpha composite src over dst with given gravity.
+    Assumes alpha channels are already premultiplied and will be unpremultiplied after.
+   */
+  VImage Composite(VImage src, VImage dst, const int gravity) {
+    if(IsInputValidForComposition(src, dst)) {
+      // Enlarge overlay src, if required
+      if (src.width() < dst.width() || src.height() < dst.height()) {
+        // Calculate the (left, top) coordinates of the output image within the input image, applying the given gravity.
+        int left;
+        int top;
+        std::tie(left, top) = CalculateCrop(dst.width(), dst.height(), src.width(), src.height(), gravity);
+        // Embed onto transparent background
+        std::vector<double> background { 0.0, 0.0, 0.0, 0.0 };
+        src = src.embed(left, top, dst.width(), dst.height(), VImage::option()
+          ->set("extend", VIPS_EXTEND_BACKGROUND)
+          ->set("background", background)
+        );
+      }
+      return CompositeImage(src, dst);
+    }
+    // If the input was not valid for composition the return the input image itself
+    return dst;
+  }
+
+  VImage Composite(VImage src, VImage dst, const int x, const int y) {
+    if(IsInputValidForComposition(src, dst)) {
+      // Enlarge overlay src, if required
+      if (src.width() < dst.width() || src.height() < dst.height()) {
+        // Calculate the (left, top) coordinates of the output image within the input image, applying the given gravity.
+        int left;
+        int top;
+        std::tie(left, top) = CalculateCrop(dst.width(), dst.height(), src.width(), src.height(), x, y);
+        // Embed onto transparent background
+        std::vector<double> background { 0.0, 0.0, 0.0, 0.0 };
+        src = src.embed(left, top, dst.width(), dst.height(), VImage::option()
+          ->set("extend", VIPS_EXTEND_BACKGROUND)
+          ->set("background", background)
+        );
+      }
+      return CompositeImage(src, dst);
+    }
+    // If the input was not valid for composition the return the input image itself
+    return dst;
+  }
+
+  bool IsInputValidForComposition(VImage src, VImage dst) {
+    using sharp::CalculateCrop;
+    using sharp::HasAlpha;
+
+    if (!HasAlpha(src)) {
+      throw VError("Overlay image must have an alpha channel");
+    }
+    if (!HasAlpha(dst)) {
+      throw VError("Image to be overlaid must have an alpha channel");
+    }
+    if (src.width() > dst.width() || src.height() > dst.height()) {
+      throw VError("Overlay image must have same dimensions or smaller");
+    }
+
+    return true;
+  }
+
+  VImage CompositeImage(VImage src, VImage dst) {
+    // Split src into non-alpha and alpha channels
+    VImage srcWithoutAlpha = src.extract_band(0, VImage::option()->set("n", src.bands() - 1));
+    VImage srcAlpha = src[src.bands() - 1] * (1.0 / 255.0);
+
+    // Split dst into non-alpha and alpha channels
+    VImage dstWithoutAlpha = dst.extract_band(0, VImage::option()->set("n", dst.bands() - 1));
+    VImage dstAlpha = dst[dst.bands() - 1] * (1.0 / 255.0);
+
+    //
+    // Compute normalized output alpha channel:
+    //
+    // References:
+    // - http://en.wikipedia.org/wiki/Alpha_compositing#Alpha_blending
+    // - https://github.com/jcupitt/ruby-vips/issues/28#issuecomment-9014826
+    //
+    // out_a = src_a + dst_a * (1 - src_a)
+    //                         ^^^^^^^^^^^
+    //                            t0
+    VImage t0 = srcAlpha.linear(-1.0, 1.0);
+    VImage outAlphaNormalized = srcAlpha + dstAlpha * t0;
+
+    //
+    // Compute output RGB channels:
+    //
+    // Wikipedia:
+    // out_rgb = (src_rgb * src_a + dst_rgb * dst_a * (1 - src_a)) / out_a
+    //                                                ^^^^^^^^^^^
+    //                                                    t0
+    //
+    // Omit division by `out_a` since `Compose` is supposed to output a
+    // premultiplied RGBA image as reversal of premultiplication is handled
+    // externally.
+    //
+    VImage outRGBPremultiplied = srcWithoutAlpha + dstWithoutAlpha * t0;
+
+    // Combine RGB and alpha channel into output image:
+    return outRGBPremultiplied.bandjoin(outAlphaNormalized * 255.0);
+  }
+
+  /*
+    Cutout src over dst with given gravity.
+   */
+  VImage Cutout(VImage mask, VImage dst, const int gravity) {
+    using sharp::CalculateCrop;
+    using sharp::HasAlpha;
+    using sharp::MaximumImageAlpha;
+
+    bool maskHasAlpha = HasAlpha(mask);
+
+    if (!maskHasAlpha && mask.bands() > 1) {
+      throw VError("Overlay image must have an alpha channel or one band");
+    }
+    if (!HasAlpha(dst)) {
+      throw VError("Image to be overlaid must have an alpha channel");
+    }
+    if (mask.width() > dst.width() || mask.height() > dst.height()) {
+      throw VError("Overlay image must have same dimensions or smaller");
+    }
+
+    // Enlarge overlay mask, if required
+    if (mask.width() < dst.width() || mask.height() < dst.height()) {
+      // Calculate the (left, top) coordinates of the output image within the input image, applying the given gravity.
+      int left;
+      int top;
+      std::tie(left, top) = CalculateCrop(dst.width(), dst.height(), mask.width(), mask.height(), gravity);
+      // Embed onto transparent background
+      std::vector<double> background { 0.0, 0.0, 0.0, 0.0 };
+      mask = mask.embed(left, top, dst.width(), dst.height(), VImage::option()
+              ->set("extend", VIPS_EXTEND_BACKGROUND)
+              ->set("background", background)
+      );
+    }
+
+    // we use the mask alpha if it has alpha
+    if(maskHasAlpha) {
+      mask = mask.extract_band(mask.bands() - 1, VImage::option()->set("n", 1));;
+    }
+
+    // Split dst into an optional alpha
+    VImage dstAlpha = dst.extract_band(dst.bands() - 1, VImage::option()->set("n", 1));
+
+    // we use the dst non-alpha
+    dst = dst.extract_band(0, VImage::option()->set("n", dst.bands() - 1));
+
+    // the range of the mask and the image need to match .. one could be
+    // 16-bit, one 8-bit
+    double const dstMax = MaximumImageAlpha(dst.interpretation());
+    double const maskMax = MaximumImageAlpha(mask.interpretation());
+
+    // combine the new mask and the existing alpha ... there are
+    // many ways of doing this, mult is the simplest
+    mask = dstMax * ((mask / maskMax) * (dstAlpha / dstMax));
+
+    // append the mask to the image data ... the mask might be float now,
+    // we must cast the format down to match the image data
+    return dst.bandjoin(mask.cast(dst.format()));
+  }
+
+  /*
+   * 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 imageWithoutAlpha = image.extract_band(0,
+        VImage::option()->set("n", image.bands() - 1));
+      VImage alpha = image[image.bands() - 1];
+      return imageWithoutAlpha.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);
+  }
+
+  /*
+   * 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);
+    }
+  }
+
+  /*
+    Calculate the Shannon entropy
+  */
+  double EntropyStrategy::operator()(VImage image) {
+    return image.hist_find().hist_entropy();
+  }
+
+  /*
+    Calculate the intensity of edges, skin tone and saturation
+  */
+  double AttentionStrategy::operator()(VImage image) {
+    // Flatten RGBA onto a mid-grey background
+    if (image.bands() == 4 && HasAlpha(image)) {
+      double const midgrey = sharp::Is16Bit(image.interpretation()) ? 32768.0 : 128.0;
+      std::vector<double> background { midgrey, midgrey, midgrey };
+      image = image.flatten(VImage::option()->set("background", background));
+    }
+    // Convert to LAB colourspace
+    VImage lab = image.colourspace(VIPS_INTERPRETATION_LAB);
+    VImage l = lab[0];
+    VImage a = lab[1];
+    VImage b = lab[2];
+    // Edge detect luminosity with the Sobel operator
+    VImage sobel = vips::VImage::new_matrixv(3, 3,
+      -1.0, 0.0, 1.0,
+      -2.0, 0.0, 2.0,
+      -1.0, 0.0, 1.0);
+    VImage edges = l.conv(sobel).abs() + l.conv(sobel.rot90()).abs();
+    // Skin tone chroma thresholds trained with http://humanae.tumblr.com/
+    VImage skin = (a >= 3) & (a <= 22) & (b >= 4) & (b <= 31);
+    // Chroma >~50% saturation
+    VImage lch = lab.colourspace(VIPS_INTERPRETATION_LCH);
+    VImage c = lch[1];
+    VImage saturation = c > 60;
+    // Find maximum in combined saliency mask
+    VImage mask = edges + skin + saturation;
+    return mask.max();
+  }
+
+  /*
+    Calculate crop area based on image entropy
+  */
+  std::tuple<int, int> Crop(
+    VImage image, int const outWidth, int const outHeight, std::function<double(VImage)> strategy
+  ) {
+    int left = 0;
+    int top = 0;
+    int const inWidth = image.width();
+    int const inHeight = image.height();
+    if (inWidth > outWidth) {
+      // Reduce width by repeated removing slices from edge with lowest score
+      int width = inWidth;
+      double leftScore = 0.0;
+      double rightScore = 0.0;
+      // Max width of each slice
+      int const maxSliceWidth = static_cast<int>(ceil((inWidth - outWidth) / 8.0));
+      while (width > outWidth) {
+        // Width of current slice
+        int const slice = std::min(width - outWidth, maxSliceWidth);
+        if (leftScore == 0.0) {
+          // Update score of left slice
+          leftScore = strategy(image.extract_area(left, 0, slice, inHeight));
+        }
+        if (rightScore == 0.0) {
+          // Update score of right slice
+          rightScore = strategy(image.extract_area(width - slice - 1, 0, slice, inHeight));
+        }
+        // Keep slice with highest score
+        if (leftScore >= rightScore) {
+          // Discard right slice
+          rightScore = 0.0;
+        } else {
+          // Discard left slice
+          leftScore = 0.0;
+          left = left + slice;
+        }
+        width = width - slice;
+      }
+    }
+    if (inHeight > outHeight) {
+      // Reduce height by repeated removing slices from edge with lowest score
+      int height = inHeight;
+      double topScore = 0.0;
+      double bottomScore = 0.0;
+      // Max height of each slice
+      int const maxSliceHeight = static_cast<int>(ceil((inHeight - outHeight) / 8.0));
+      while (height > outHeight) {
+        // Height of current slice
+        int const slice = std::min(height - outHeight, maxSliceHeight);
+        if (topScore == 0.0) {
+          // Update score of top slice
+          topScore = strategy(image.extract_area(0, top, inWidth, slice));
+        }
+        if (bottomScore == 0.0) {
+          // Update score of bottom slice
+          bottomScore = strategy(image.extract_area(0, height - slice - 1, inWidth, slice));
+        }
+        // Keep slice with highest score
+        if (topScore >= bottomScore) {
+          // Discard bottom slice
+          bottomScore = 0.0;
+        } else {
+          // Discard top slice
+          topScore = 0.0;
+          top = top + slice;
+        }
+        height = height - slice;
+      }
+    }
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Insert a tile cache to prevent over-computation of any previous operations in the pipeline
+  */
+  VImage TileCache(VImage image, double const factor) {
+    int tile_width;
+    int tile_height;
+    int scanline_count;
+    vips_get_tile_size(image.get_image(), &tile_width, &tile_height, &scanline_count);
+    double const need_lines = 1.2 * scanline_count / factor;
+    return image.tilecache(VImage::option()
+      ->set("tile_width", image.width())
+      ->set("tile_height", 10)
+      ->set("max_tiles", static_cast<int>(round(1.0 + need_lines / 10.0)))
+      ->set("access", VIPS_ACCESS_SEQUENTIAL)
+      ->set("threaded", TRUE)
+    );
+  }
+
+  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);
+  }
+
+  VImage Trim(VImage image, int const tolerance) {
+    using sharp::MaximumImageAlpha;
+    // An equivalent of ImageMagick's -trim in C++ ... automatically remove
+    // "boring" image edges.
+
+    // We use .project to sum the rows and columns of a 0/255 mask image, the first
+    // non-zero row or column is the object edge. We make the mask image with an
+    // amount-different-from-background image plus a threshold.
+
+    // find the value of the pixel at (0, 0) ... we will search for all pixels
+    // significantly different from this
+    std::vector<double> background = image(0, 0);
+
+    double const max = MaximumImageAlpha(image.interpretation());
+
+    // we need to smooth the image, subtract the background from every pixel, take
+    // the absolute value of the difference, then threshold
+    VImage mask = (image.median(3) - background).abs() > (max * tolerance / 100);
+
+    // sum mask rows and columns, then search for the first non-zero sum in each
+    // direction
+    VImage rows;
+    VImage columns = mask.project(&rows);
+
+    VImage profileLeftV;
+    VImage profileLeftH = columns.profile(&profileLeftV);
+
+    VImage profileRightV;
+    VImage profileRightH = columns.fliphor().profile(&profileRightV);
+
+    VImage profileTopV;
+    VImage profileTopH = rows.profile(&profileTopV);
+
+    VImage profileBottomV;
+    VImage profileBottomH = rows.flipver().profile(&profileBottomV);
+
+    int left = static_cast<int>(floor(profileLeftV.min()));
+    int right = columns.width() - static_cast<int>(floor(profileRightV.min()));
+    int top = static_cast<int>(floor(profileTopH.min()));
+    int bottom = rows.height() - static_cast<int>(floor(profileBottomH.min()));
+
+    int width = right - left;
+    int height = bottom - top;
+
+    if(width <= 0 || height <= 0) {
+      throw VError("Unexpected error while trimming. Try to lower the tolerance");
+    }
+
+    // and now crop the original image
+    return image.extract_area(left, top, width, height);
+  }
+
+}  // namespace sharp

src/operations.h

@@ -0,0 +1,111 @@
+#ifndef SRC_OPERATIONS_H_
+#define SRC_OPERATIONS_H_
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vips/vips8>
+
+using vips::VImage;
+
+namespace sharp {
+
+  /*
+    Alpha composite src over dst with given gravity.
+    Assumes alpha channels are already premultiplied and will be unpremultiplied after.
+   */
+  VImage Composite(VImage src, VImage dst, const int gravity);
+
+  /*
+    Alpha composite src over dst with given x and y offsets.
+    Assumes alpha channels are already premultiplied and will be unpremultiplied after.
+   */
+  VImage Composite(VImage src, VImage dst, const int x, const int y);
+
+  /*
+    Check if the src and dst Images for composition operation are valid
+  */
+  bool IsInputValidForComposition(VImage src, VImage dst);
+
+  /*
+    Given a valid src and dst, returns the composite of the two images
+  */
+  VImage CompositeImage(VImage src, VImage dst);
+
+  /*
+    Cutout src over dst with given gravity.
+  */
+  VImage Cutout(VImage src, VImage dst, const int gravity);
+
+  /*
+   * 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);
+
+  /*
+    Crop strategy functors
+  */
+  struct EntropyStrategy {
+    double operator()(VImage image);
+  };
+  struct AttentionStrategy {
+    double operator()(VImage image);
+  };
+
+  /*
+    Calculate crop area based on given strategy (Entropy, Attention)
+  */
+  std::tuple<int, int> Crop(
+    VImage image, int const outWidth, int const outHeight, std::function<double(VImage)> strategy
+  );
+
+  /*
+    Insert a tile cache to prevent over-computation of any previous operations in the pipeline
+  */
+  VImage TileCache(VImage image, double const factor);
+
+  /*
+    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, int const tolerance);
+
+}  // namespace sharp
+
+#endif  // SRC_OPERATIONS_H_

src/pipeline.h

@@ -0,0 +1,178 @@
+#ifndef SRC_PIPELINE_H_
+#define SRC_PIPELINE_H_
+
+#include <memory>
+
+#include <vips/vips8>
+
+#include "nan.h"
+#include "common.h"
+
+NAN_METHOD(pipeline);
+
+enum class Canvas {
+  CROP,
+  EMBED,
+  MAX,
+  MIN,
+  IGNORE_ASPECT
+};
+
+struct PipelineBaton {
+  sharp::InputDescriptor *input;
+  std::string iccProfilePath;
+  int limitInputPixels;
+  std::string formatOut;
+  std::string fileOut;
+  void *bufferOut;
+  size_t bufferOutLength;
+  sharp::InputDescriptor *overlay;
+  int overlayGravity;
+  int overlayXOffset;
+  int overlayYOffset;
+  bool overlayTile;
+  bool overlayCutout;
+  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 crop;
+  int cropCalcLeft;
+  int cropCalcTop;
+  std::string kernel;
+  std::string interpolator;
+  bool centreSampling;
+  double background[4];
+  bool flatten;
+  bool negate;
+  double blurSigma;
+  double sharpenSigma;
+  double sharpenFlat;
+  double sharpenJagged;
+  int threshold;
+  bool thresholdGrayscale;
+  int trimTolerance;
+  double gamma;
+  bool greyscale;
+  bool normalise;
+  int angle;
+  bool rotateBeforePreExtract;
+  bool flip;
+  bool flop;
+  int extendTop;
+  int extendBottom;
+  int extendLeft;
+  int extendRight;
+  bool withoutEnlargement;
+  VipsAccess accessMethod;
+  int jpegQuality;
+  bool jpegProgressive;
+  std::string jpegChromaSubsampling;
+  bool jpegTrellisQuantisation;
+  bool jpegOvershootDeringing;
+  bool jpegOptimiseScans;
+  bool pngProgressive;
+  int pngCompressionLevel;
+  bool pngAdaptiveFiltering;
+  int webpQuality;
+  int tiffQuality;
+  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;
+  VipsInterpretation colourspace;
+  int tileSize;
+  int tileOverlap;
+  VipsForeignDzContainer tileContainer;
+  VipsForeignDzLayout tileLayout;
+  std::string tileFormat;
+
+  PipelineBaton():
+    input(nullptr),
+    limitInputPixels(0),
+    bufferOutLength(0),
+    overlay(nullptr),
+    overlayGravity(0),
+    overlayXOffset(-1),
+    overlayYOffset(-1),
+    overlayTile(false),
+    overlayCutout(false),
+    topOffsetPre(-1),
+    topOffsetPost(-1),
+    channels(0),
+    canvas(Canvas::CROP),
+    crop(0),
+    cropCalcLeft(-1),
+    cropCalcTop(-1),
+    centreSampling(false),
+    flatten(false),
+    negate(false),
+    blurSigma(0.0),
+    sharpenSigma(0.0),
+    sharpenFlat(1.0),
+    sharpenJagged(2.0),
+    threshold(0),
+    thresholdGrayscale(true),
+    trimTolerance(0),
+    gamma(0.0),
+    greyscale(false),
+    normalise(false),
+    angle(0),
+    flip(false),
+    flop(false),
+    extendTop(0),
+    extendBottom(0),
+    extendLeft(0),
+    extendRight(0),
+    withoutEnlargement(false),
+    jpegQuality(80),
+    jpegProgressive(false),
+    jpegChromaSubsampling("4:2:0"),
+    jpegTrellisQuantisation(false),
+    jpegOvershootDeringing(false),
+    jpegOptimiseScans(false),
+    pngProgressive(false),
+    pngCompressionLevel(6),
+    pngAdaptiveFiltering(true),
+    webpQuality(80),
+    tiffQuality(80),
+    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),
+    colourspace(VIPS_INTERPRETATION_LAST),
+    tileSize(256),
+    tileOverlap(0),
+    tileContainer(VIPS_FOREIGN_DZ_CONTAINER_FS),
+    tileLayout(VIPS_FOREIGN_DZ_LAYOUT_DZ) {
+      background[0] = 0.0;
+      background[1] = 0.0;
+      background[2] = 0.0;
+      background[3] = 255.0;
+    }
+};
+
+#endif  // SRC_PIPELINE_H_

src/sharp.cc

@@ -1,777 +1,35 @@
 #include <node.h>
-#include <node_buffer.h>
-#include <math.h>
-#include <string>
-#include <string.h>
-#include <tuple>
-#include <vips/vips.h>
+#include <vips/vips8>
 
 #include "nan.h"
 
-using namespace v8;
-using namespace node;
+#include "common.h"
+#include "metadata.h"
+#include "pipeline.h"
+#include "utilities.h"
 
-struct resize_baton {
-  std::string file_in;
-  void* buffer_in;
-  size_t buffer_in_len;
-  std::string output;
-  void* buffer_out;
-  size_t buffer_out_len;
-  int width;
-  int height;
-  bool crop;
-  int gravity;
-  bool max;
-  VipsExtend extend;
-  bool sharpen;
-  std::string interpolator;
-  bool progressive;
-  bool without_enlargement;
-  VipsAccess access_method;
-  int quality;
-  int compressionLevel;
-  int angle;
-  std::string err;
+NAN_MODULE_INIT(init) {
+  vips_init("sharp");
 
-  resize_baton():
-    buffer_in_len(0),
-    buffer_out_len(0),
-    crop(false),
-    gravity(0),
-    max(false),
-    sharpen(false),
-    progressive(false),
-    without_enlargement(false) {}
-};
-
-typedef enum {
-  UNKNOWN,
-  JPEG,
-  PNG,
-  WEBP,
-  TIFF,
-  MAGICK
-} ImageType;
-
-unsigned char const MARKER_JPEG[] = {0xff, 0xd8};
-unsigned char const MARKER_PNG[] = {0x89, 0x50};
-unsigned char const MARKER_WEBP[] = {0x52, 0x49};
-
-// How many tasks are in the queue?
-volatile int counter_queue = 0;
-// How many tasks are being processed?
-volatile int counter_process = 0;
-
-static bool ends_with(std::string const &str, std::string const &end) {
-  return str.length() >= end.length() && 0 == str.compare(str.length() - end.length(), end.length(), end);
-}
-
-static bool is_jpeg(std::string const &str) {
-  return ends_with(str, ".jpg") || ends_with(str, ".jpeg") || ends_with(str, ".JPG") || ends_with(str, ".JPEG");
-}
-
-static bool is_png(std::string const &str) {
-  return ends_with(str, ".png") || ends_with(str, ".PNG");
-}
-
-static bool is_webp(std::string const &str) {
-  return ends_with(str, ".webp") || ends_with(str, ".WEBP");
-}
-
-static bool is_tiff(std::string const &str) {
-  return ends_with(str, ".tif") || ends_with(str, ".tiff") || ends_with(str, ".TIF") || ends_with(str, ".TIFF");
-}
-
-static void resize_error(resize_baton *baton, VipsImage *unref) {
-  (baton->err).append(vips_error_buffer());
-  vips_error_clear();
-  g_object_unref(unref);
-  vips_thread_shutdown();
-  return;
-}
-
-/*
-  Calculate the angle of rotation for the output image.
-  In order of priority:
-   1. Use explicitly requested angle (supports 90, 180, 270)
-   2. Use input image EXIF Orientation header (does not support mirroring)
-   3. Otherwise default to zero, i.e. no rotation
-*/
-static VipsAngle
-sharp_calc_rotation(int const angle, VipsImage const *input) {
-  VipsAngle rotate = VIPS_ANGLE_0;
-  if (angle == -1) {
-    const char *exif;
-    if (!vips_image_get_string(input, "exif-ifd0-Orientation", &exif)) {
-      if (exif[0] == 0x36) { // "6"
-        rotate = VIPS_ANGLE_90;
-      } else if (exif[0] == 0x33) { // "3"
-        rotate = VIPS_ANGLE_180;
-      } else if (exif[0] == 0x38) { // "8"
-        rotate = VIPS_ANGLE_270;
-      }
-    }
-  } else {
-    if (angle == 90) {
-      rotate = VIPS_ANGLE_90;
-    } else if (angle == 180) {
-      rotate = VIPS_ANGLE_180;
-    } else if (angle == 270) {
-      rotate = VIPS_ANGLE_270;
-    }
-  }
-  return rotate;
-}
-
-/*
-  Calculate the (left, top) coordinates of the output image
-  within the input image, applying the given gravity.
-*/
-static std::tuple<int, int>
-sharp_calc_crop(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);
-}
-
-/*
-  Initialise a VipsImage from a buffer. Supports JPEG, PNG and WebP.
-  Returns the ImageType detected, if any.
-*/
-static ImageType
-sharp_init_image_from_buffer(VipsImage **image, void *buffer, size_t const length, VipsAccess const access) {
-  ImageType imageType = UNKNOWN;
-  if (memcmp(MARKER_JPEG, buffer, 2) == 0) {
-    if (!vips_jpegload_buffer(buffer, length, image, "access", access, NULL)) {
-      imageType = JPEG;
-    }
-  } else if(memcmp(MARKER_PNG, buffer, 2) == 0) {
-    if (!vips_pngload_buffer(buffer, length, image, "access", access, NULL)) {
-      imageType = PNG;
-    }
-  } else if(memcmp(MARKER_WEBP, buffer, 2) == 0) {
-    if (!vips_webpload_buffer(buffer, length, image, "access", access, NULL)) {
-      imageType = WEBP;
-    }
-  }
-  return imageType;
-}
-
-/*
-  Initialise a VipsImage from a file.
-  Returns the ImageType detected, if any.
-*/
-static ImageType
-sharp_init_image_from_file(VipsImage **image, char const *file, VipsAccess const access) {
-  ImageType imageType = UNKNOWN;
-  if (vips_foreign_is_a("jpegload", file)) {
-    if (!vips_jpegload(file, image, "access", access, NULL)) {
-      imageType = JPEG;
-    }
-  } else if (vips_foreign_is_a("pngload", file)) {
-    if (!vips_pngload(file, image, "access", access, NULL)) {
-      imageType = PNG;
-    }
-  } else if (vips_foreign_is_a("webpload", file)) {
-    if (!vips_webpload(file, image, "access", access, NULL)) {
-      imageType = WEBP;
-    }
-  } else if (vips_foreign_is_a("tiffload", file)) {
-    if (!vips_tiffload(file, image, "access", access, NULL)) {
-      imageType = TIFF;
-    }
-  } else if(vips_foreign_is_a("magickload", file)) {
-    if (!vips_magickload(file, image, "access", access, NULL)) {
-      imageType = MAGICK;
-    }
-  }
-  return imageType;
-}
-
-// Metadata
-
-struct metadata_baton {
-  // Input
-  std::string file_in;
-  void* buffer_in;
-  size_t buffer_in_len;
-  // Output
-  std::string format;
-  int width;
-  int height;
-  std::string space;
-  int channels;
-  int orientation;
-  std::string err;
-
-  metadata_baton():
-    buffer_in_len(0),
-    orientation(0) {}
-};
-
-class MetadataWorker : public NanAsyncWorker {
-
-  public:
-    MetadataWorker(NanCallback *callback, metadata_baton *baton) : NanAsyncWorker(callback), baton(baton) {}
-    ~MetadataWorker() {}
-
-  void Execute() {
-    // Decrement queued task counter
-    g_atomic_int_dec_and_test(&counter_queue);
-
-    ImageType imageType = UNKNOWN;
-    VipsImage *image = vips_image_new();
-    if (baton->buffer_in_len > 1) {
-      // From buffer
-      imageType = sharp_init_image_from_buffer(&image, baton->buffer_in, baton->buffer_in_len, VIPS_ACCESS_RANDOM);
-      if (imageType == UNKNOWN) {
-        (baton->err).append("Input buffer contains unsupported image format");
-      }
-    } else {
-      // From file
-      imageType = sharp_init_image_from_file(&image, baton->file_in.c_str(), VIPS_ACCESS_RANDOM);
-      if (imageType == UNKNOWN) {
-        (baton->err).append("File is of an unsupported image format");
-      }
-    }
-    if (imageType != UNKNOWN) {
-      // Image type
-      switch (imageType) {
-        case JPEG: baton->format = "jpeg"; break;
-        case PNG: baton->format = "png"; break;
-        case WEBP: baton->format = "webp"; break;
-        case TIFF: baton->format = "tiff"; break;
-        case MAGICK: baton->format = "magick"; break;
-        case UNKNOWN: default: baton->format = "";
-      }
-      // VipsImage attributes
-      baton->width = image->Xsize;
-      baton->height = image->Ysize;
-      baton->space = vips_enum_nick(VIPS_TYPE_INTERPRETATION, image->Type);
-      baton->channels = image->Bands;
-      // EXIF Orientation
-      const char *exif;
-      if (!vips_image_get_string(image, "exif-ifd0-Orientation", &exif)) {
-        baton->orientation = atoi(&exif[0]);
-      }
-    }
-    // Clean up
-    g_object_unref(image);
-    vips_error_clear();
-    vips_thread_shutdown();
-  }
-
-  void HandleOKCallback () {
-    NanScope();
-
-    Handle<Value> argv[2] = { NanNull(), NanNull() };
-    if (!baton->err.empty()) {
-      // Error
-      argv[0] = NanNew<String>(baton->err.data(), baton->err.size());
-    } 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));
-      if (baton->orientation > 0) {
-        info->Set(NanNew<String>("orientation"), NanNew<Number>(baton->orientation));
-      }
-      argv[1] = info;
-    }
-    delete baton;
-
-    // Return to JavaScript
-    callback->Call(2, argv);
-  }
-
-  private:
-    metadata_baton* baton;
-};
-
-/*
-  metadata(options, callback)
-*/
-NAN_METHOD(metadata) {
-  NanScope();
-
-  // V8 objects are converted to non-V8 types held in the baton struct
-  metadata_baton *baton = new metadata_baton;
-  Local<Object> options = args[0]->ToObject();
-
-  // Input filename
-  baton->file_in = *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->buffer_in_len = Buffer::Length(buffer);
-    baton->buffer_in = Buffer::Data(buffer);
-  }
-
-  // Join queue for worker thread
-  NanCallback *callback = new NanCallback(args[1].As<v8::Function>());
-  NanAsyncQueueWorker(new MetadataWorker(callback, baton));
-
-  // Increment queued task counter
-  g_atomic_int_inc(&counter_queue);
-
-  NanReturnUndefined();
-}
-
-// Resize
-
-class ResizeWorker : public NanAsyncWorker {
-  public:
-    ResizeWorker(NanCallback *callback, resize_baton *baton) : NanAsyncWorker(callback), baton(baton) {}
-    ~ResizeWorker() {}
-
-  void Execute() {
-    // Decrement queued task counter
-    g_atomic_int_dec_and_test(&counter_queue);
-    // Increment processing task counter
-    g_atomic_int_inc(&counter_process);
-
-    // Input
-    ImageType inputImageType = UNKNOWN;
-    VipsImage *in = vips_image_new();
-    if (baton->buffer_in_len > 1) {
-      // From buffer
-      inputImageType = sharp_init_image_from_buffer(&in, baton->buffer_in, baton->buffer_in_len, baton->access_method);
-      if (inputImageType == UNKNOWN) {
-        (baton->err).append("Input buffer contains unsupported image format");
-      }
-    } else {
-      // From file
-      inputImageType = sharp_init_image_from_file(&in, baton->file_in.c_str(), baton->access_method);
-      if (inputImageType == UNKNOWN) {
-        (baton->err).append("File is of an unsupported image format");
-      }
-    }
-    if (inputImageType == UNKNOWN) {
-      return resize_error(baton, in);
-    }
-
-    // Get input image width and height
-    int inputWidth = in->Xsize;
-    int inputHeight = in->Ysize;
-
-    // Calculate angle of rotation, to be carried out later
-    VipsAngle rotation = sharp_calc_rotation(baton->angle, in);
-    if (rotation == VIPS_ANGLE_90 || rotation == VIPS_ANGLE_270) {
-      // Swap input output width and height when rotating by 90 or 270 degrees
-      int swap = inputWidth;
-      inputWidth = inputHeight;
-      inputHeight = swap;
-    }
-
-    // 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->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->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;
-    }
-    int shrink = floor(factor);
-    if (shrink < 1) {
-      shrink = 1;
-    }
-    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->without_enlargement) {
-      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
-    int shrink_on_load = 1;
-    if (inputImageType == JPEG) {
-      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;
-      }
-    }
-    VipsImage *shrunk_on_load = vips_image_new();
-    if (shrink_on_load > 1) {
-      // Recalculate integral shrink and double residual
-      factor = std::max(factor, 1.0);
-      shrink = floor(factor);
-      residual = static_cast<double>(shrink) / factor;
-      // Reload input using shrink-on-load
-      if (baton->buffer_in_len > 1) {
-        if (vips_jpegload_buffer(baton->buffer_in, baton->buffer_in_len, &shrunk_on_load, "shrink", shrink_on_load, NULL)) {
-          return resize_error(baton, in);
-        }
-      } else {
-        if (vips_jpegload((baton->file_in).c_str(), &shrunk_on_load, "shrink", shrink_on_load, NULL)) {
-          return resize_error(baton, in);
-        }
-      }
-    } else {
-      vips_copy(in, &shrunk_on_load, NULL);
-    }
-    g_object_unref(in);
-
-    VipsImage *shrunk = vips_image_new();
-    if (shrink > 1) {
-      // Use vips_shrink with the integral reduction
-      if (vips_shrink(shrunk_on_load, &shrunk, shrink, shrink, NULL)) {
-        return resize_error(baton, shrunk_on_load);
-      }
-      // Recalculate residual float based on dimensions of required vs shrunk images
-      double shrunkWidth = shrunk->Xsize;
-      double shrunkHeight = shrunk->Ysize;
-      if (rotation == VIPS_ANGLE_90 || rotation == VIPS_ANGLE_270) {
-        // 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->crop || baton->max) {
-        residual = std::max(residualx, residualy);
-      } else {
-        residual = std::min(residualx, residualy);
-      }
-    } else {
-      vips_copy(shrunk_on_load, &shrunk, NULL);
-    }
-    g_object_unref(shrunk_on_load);
-
-    // Use vips_affine with the remaining float part
-    VipsImage *affined = vips_image_new();
-    if (residual != 0) {
-      // Create interpolator - "bilinear" (default), "bicubic" or "nohalo"
-      VipsInterpolate *interpolator = vips_interpolate_new(baton->interpolator.c_str());
-      // Perform affine transformation
-      if (vips_affine(shrunk, &affined, residual, 0, 0, residual, "interpolate", interpolator, NULL)) {
-        g_object_unref(interpolator);
-        return resize_error(baton, shrunk);
-      }
-      g_object_unref(interpolator);
-    } else {
-      vips_copy(shrunk, &affined, NULL);
-    }
-    g_object_unref(shrunk);
-
-    // Rotate
-    VipsImage *rotated = vips_image_new();
-    if (rotation != VIPS_ANGLE_0) {
-      if (vips_rot(affined, &rotated, rotation, NULL)) {
-        return resize_error(baton, affined);
-      }
-    } else {
-      vips_copy(affined, &rotated, NULL);
-    }
-    g_object_unref(affined);
-
-    // Crop/embed
-    VipsImage *canvased = vips_image_new();
-    if (rotated->Xsize != baton->width || rotated->Ysize != baton->height) {
-      if (baton->crop || baton->max) {
-        // Crop/max
-        int left;
-        int top;
-        std::tie(left, top) = sharp_calc_crop(rotated->Xsize, rotated->Ysize, baton->width, baton->height, baton->gravity);
-        int width = std::min(rotated->Xsize, baton->width);
-        int height = std::min(rotated->Ysize, baton->height);
-        if (vips_extract_area(rotated, &canvased, left, top, width, height, NULL)) {
-          return resize_error(baton, rotated);
-        }
-      } else {
-        // Embed
-        int left = (baton->width - rotated->Xsize) / 2;
-        int top = (baton->height - rotated->Ysize) / 2;
-        if (vips_embed(rotated, &canvased, left, top, baton->width, baton->height, "extend", baton->extend, NULL)) {
-          return resize_error(baton, rotated);
-        }
-      }
-    } else {
-      vips_copy(rotated, &canvased, NULL);
-    }
-    g_object_unref(rotated);
-
-    // Mild sharpen
-    VipsImage *sharpened = vips_image_new();
-    if (baton->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);
-      if (vips_conv(canvased, &sharpened, sharpen, NULL)) {
-        g_object_unref(sharpen);
-        return resize_error(baton, canvased);
-      }
-      g_object_unref(sharpen);
-    } else {
-      vips_copy(canvased, &sharpened, NULL);
-    }
-    g_object_unref(canvased);
-
-    // Always convert to sRGB colour space
-    VipsImage *colourspaced = vips_image_new();
-    vips_colourspace(sharpened, &colourspaced, VIPS_INTERPRETATION_sRGB, NULL);
-    g_object_unref(sharpened);
-
-    // Generate image tile cache when interlace output is required
-    VipsImage *cached = vips_image_new();
-    if (baton->progressive) {
-      if (vips_tilecache(colourspaced, &cached, "threaded", TRUE, "persistent", TRUE, "max_tiles", -1, NULL)) {
-        return resize_error(baton, colourspaced);
-      }
-    } else {
-      vips_copy(colourspaced, &cached, NULL);
-    }
-    g_object_unref(colourspaced);
-
-    // Output
-    VipsImage *output = cached;
-    if (baton->output == "__jpeg" || (baton->output == "__input" && inputImageType == JPEG)) {
-      // Write JPEG to buffer
-      if (vips_jpegsave_buffer(output, &baton->buffer_out, &baton->buffer_out_len, "strip", TRUE, "Q", baton->quality, "optimize_coding", TRUE, "interlace", baton->progressive, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (baton->output == "__png" || (baton->output == "__input" && inputImageType == PNG)) {
-      // Write PNG to buffer
-      if (vips_pngsave_buffer(output, &baton->buffer_out, &baton->buffer_out_len, "strip", TRUE, "compression", baton->compressionLevel, "interlace", baton->progressive, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (baton->output == "__webp" || (baton->output == "__input" && inputImageType == WEBP)) {
-      // Write WEBP to buffer
-      if (vips_webpsave_buffer(output, &baton->buffer_out, &baton->buffer_out_len, "strip", TRUE, "Q", baton->quality, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (is_jpeg(baton->output))  {
-      // Write JPEG to file
-      if (vips_jpegsave(output, baton->output.c_str(), "strip", TRUE, "Q", baton->quality, "optimize_coding", TRUE, "interlace", baton->progressive, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (is_png(baton->output)) {
-      // Write PNG to file
-      if (vips_pngsave(output, baton->output.c_str(), "strip", TRUE, "compression", baton->compressionLevel, "interlace", baton->progressive, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (is_webp(baton->output)) {
-      // Write WEBP to file
-      if (vips_webpsave(output, baton->output.c_str(), "strip", TRUE, "Q", baton->quality, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else if (is_tiff(baton->output)) {
-      // Write TIFF to file
-      if (vips_tiffsave(output, baton->output.c_str(), "strip", TRUE, "compression", VIPS_FOREIGN_TIFF_COMPRESSION_JPEG, "Q", baton->quality, NULL)) {
-        return resize_error(baton, output);
-      }
-    } else {
-      (baton->err).append("Unsupported output " + baton->output);
-    }
-    g_object_unref(output);
-
-    // 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] = NanNew<String>(baton->err.data(), baton->err.size());
-    } else {
-      // Info Object
-      Local<Object> info = NanNew<Object>();
-      info->Set(NanNew<String>("width"), NanNew<Number>(baton->width));
-      info->Set(NanNew<String>("height"), NanNew<Number>(baton->height));
-
-      if (baton->buffer_out_len > 0) {
-        // Buffer
-        argv[1] = NanNewBufferHandle((char *)baton->buffer_out, baton->buffer_out_len);
-        g_free(baton->buffer_out);
-        argv[2] = info;
-      } else {
-        // File
-        argv[1] = info;
-      }
-    }
-    delete baton;
-
-    // Decrement processing task counter
-    g_atomic_int_dec_and_test(&counter_process);
-
-    // Return to JavaScript
-    callback->Call(3, argv);
-  }
-
- private:
-  resize_baton* baton;
-};
-
-/*
-  resize(options, output, callback)
-*/
-NAN_METHOD(resize) {
-  NanScope();
-
-  // V8 objects are converted to non-V8 types held in the baton struct
-  resize_baton *baton = new resize_baton;
-  Local<Object> options = args[0]->ToObject();
-
-  // Input filename
-  baton->file_in = *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->buffer_in_len = Buffer::Length(buffer);
-    baton->buffer_in = Buffer::Data(buffer);
-  }
-  // Output image dimensions
-  baton->width = options->Get(NanNew<String>("width"))->Int32Value();
-  baton->height = options->Get(NanNew<String>("height"))->Int32Value();
-  // Canvas options
-  Local<String> canvas = options->Get(NanNew<String>("canvas"))->ToString();
-  if (canvas->Equals(NanNew<String>("c"))) {
-    baton->crop = true;
-  } else if (canvas->Equals(NanNew<String>("w"))) {
-    baton->extend = VIPS_EXTEND_WHITE;
-  } else if (canvas->Equals(NanNew<String>("b"))) {
-    baton->extend = VIPS_EXTEND_BLACK;
-  } else if (canvas->Equals(NanNew<String>("m"))) {
-    baton->max = true;
-  }
-  // Other options
-  baton->gravity = options->Get(NanNew<String>("gravity"))->Int32Value();
-  baton->sharpen = options->Get(NanNew<String>("sharpen"))->BooleanValue();
-  baton->interpolator = *String::Utf8Value(options->Get(NanNew<String>("interpolator"))->ToString());
-  baton->progressive = options->Get(NanNew<String>("progressive"))->BooleanValue();
-  baton->without_enlargement = options->Get(NanNew<String>("withoutEnlargement"))->BooleanValue();
-  baton->access_method = options->Get(NanNew<String>("sequentialRead"))->BooleanValue() ? VIPS_ACCESS_SEQUENTIAL : VIPS_ACCESS_RANDOM;
-  baton->quality = options->Get(NanNew<String>("quality"))->Int32Value();
-  baton->compressionLevel = options->Get(NanNew<String>("compressionLevel"))->Int32Value();
-  baton->angle = options->Get(NanNew<String>("angle"))->Int32Value();
-  // 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(&counter_queue);
-
-  NanReturnUndefined();
-}
-
-/*
-  Get and set cache memory and item limits
-*/
-NAN_METHOD(cache) {
-  NanScope();
-
-  // Set cache memory limit
-  if (args[0]->IsInt32()) {
-    vips_cache_set_max_mem(args[0]->Int32Value() * 1048576);
-  }
-
-  // Set cache items limit
-  if (args[1]->IsInt32()) {
-    vips_cache_set_max(args[1]->Int32Value());
-  }
-
-  // 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 internal counters (queued tasks, processing tasks)
-*/
-NAN_METHOD(counters) {
-  NanScope();
-  Local<Object> counters = NanNew<Object>();
-  counters->Set(NanNew<String>("queue"), NanNew<Number>(counter_queue));
-  counters->Set(NanNew<String>("process"), NanNew<Number>(counter_process));
-  NanReturnValue(counters);
-}
-
-static void at_exit(void* arg) {
-  NanScope();
-  vips_shutdown();
-}
-
-extern "C" void init(Handle<Object> target) {
-  NanScope();
-  vips_init("");
-  AtExit(at_exit);
-  // Set libvips operation cache limits
-  vips_cache_set_max_mem(100 * 1048576); // 100 MB
-  vips_cache_set_max(500); // 500 operations
   // 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, "counters", counters);
+  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());
 }
 
 NODE_MODULE(sharp, init)

src/utilities.cc

@@ -0,0 +1,259 @@
+#include <cmath>
+#include <node.h>
+#include <vips/vips8>
+#include <vips/vector.h>
+
+#include "nan.h"
+
+#include "common.h"
+#include "operations.h"
+#include "utilities.h"
+
+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 limits
+*/
+NAN_METHOD(cache) {
+  HandleScope();
+
+  // 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());
+  }
+
+  // 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 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) {
+  HandleScope();
+
+  // Set concurrency
+  if (info[0]->IsInt32()) {
+    vips_concurrency_set(To<int32_t>(info[0]).FromJust());
+  }
+  // Get concurrency
+  info.GetReturnValue().Set(New<Integer>(vips_concurrency_get()));
+}
+
+/*
+  Get internal counters (queued tasks, processing tasks)
+*/
+NAN_METHOD(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) {
+  HandleScope();
+  char version[9];
+  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 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

@@ -0,0 +1,14 @@
+#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  // SRC_UTILITIES_H_

test/bench/package.json

@@ -0,0 +1,25 @@
+{
+  "name": "sharp-benchmark",
+  "version": "0.0.1",
+  "private": true,
+  "author": "Lovell Fuller <npm@lovell.info>",
+  "description": "Benchmark and performance tests for sharp",
+  "scripts": {
+    "test": "VIPS_WARNING=0 node perf && node random && node parallel"
+  },
+  "devDependencies": {
+    "async": "^2.1.4",
+    "benchmark": "^2.1.2",
+    "gm": "^1.23.0",
+    "imagemagick": "^0.1.3",
+    "imagemagick-native": "^1.9.3",
+    "jimp": "^0.2.27",
+    "lwip": "^0.0.9",
+    "mapnik": "^3.5.14",
+    "semver": "^5.3.0"
+  },
+  "license": "Apache-2.0",
+  "engines": {
+    "node": ">=4"
+  }
+}

test/bench/parallel.js

@@ -0,0 +1,44 @@
+'use strict';
+
+process.env.UV_THREADPOOL_SIZE = 64;
+
+const assert = require('assert');
+const async = require('async');
+
+const sharp = require('../../');
+const fixtures = require('../fixtures');
+
+const width = 720;
+const height = 480;
+
+sharp.concurrency(1);
+sharp.simd(true);
+
+const timer = setInterval(function () {
+  console.dir(sharp.counters());
+}, 100);
+
+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) {
+        buffer = null;
+        callback(err, new Date().getTime() - start);
+      });
+    },
+    function (err, ids) {
+      assert(!err);
+      assert(ids.length === parallelism);
+      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 () {
+  clearInterval(timer);
+  console.dir(sharp.counters());
+});

test/bench/perf.js

@@ -0,0 +1,985 @@
+'use strict';
+
+const fs = require('fs');
+
+const async = require('async');
+const assert = require('assert');
+const Benchmark = require('benchmark');
+
+// Contenders
+const gm = require('gm');
+const imagemagick = require('imagemagick');
+const mapnik = require('mapnik');
+const jimp = require('jimp');
+const sharp = require('../../');
+let imagemagickNative;
+try {
+  imagemagickNative = require('imagemagick-native');
+} catch (err) {
+  console.log('Excluding imagemagick-native');
+}
+let lwip;
+try {
+  lwip = require('lwip');
+} catch (err) {
+  console.log('Excluding lwip');
+}
+
+const fixtures = require('../fixtures');
+
+const width = 720;
+const height = 588;
+
+// Disable libvips cache to ensure tests are as fair as they can be
+sharp.cache(false);
+// Enable use of SIMD
+sharp.simd(true);
+
+async.series({
+  'jpeg': function (callback) {
+    const inputJpgBuffer = fs.readFileSync(fixtures.inputJpg);
+    const jpegSuite = new Benchmark.Suite('jpeg');
+    // jimp
+    jpegSuite.add('jimp-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        jimp.read(inputJpgBuffer, function (err, image) {
+          if (err) {
+            throw err;
+          } else {
+            image
+              .resize(width, height)
+              .quality(80)
+              .getBuffer(jimp.MIME_JPEG, function (err) {
+                if (err) {
+                  throw err;
+                } else {
+                  deferred.resolve();
+                }
+              });
+          }
+        });
+      }
+    }).add('jimp-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        jimp.read(fixtures.inputJpg, function (err, image) {
+          if (err) {
+            throw err;
+          } else {
+            image
+              .resize(width, height)
+              .quality(80)
+              .write(fixtures.outputJpg, function (err) {
+                if (err) {
+                  throw err;
+                } else {
+                  deferred.resolve();
+                }
+              });
+          }
+        });
+      }
+    });
+    // lwip
+    if (typeof lwip !== 'undefined') {
+      jpegSuite.add('lwip-file-file', {
+        defer: true,
+        fn: function (deferred) {
+          lwip.open(fixtures.inputJpg, function (err, image) {
+            if (err) {
+              throw err;
+            }
+            image.resize(width, height, 'lanczos', function (err, image) {
+              if (err) {
+                throw err;
+              }
+              image.writeFile(fixtures.outputJpg, {quality: 80}, function (err) {
+                if (err) {
+                  throw err;
+                }
+                deferred.resolve();
+              });
+            });
+          });
+        }
+      }).add('lwip-buffer-buffer', {
+        defer: true,
+        fn: function (deferred) {
+          lwip.open(inputJpgBuffer, 'jpg', function (err, image) {
+            if (err) {
+              throw err;
+            }
+            image.resize(width, height, 'lanczos', function (err, image) {
+              if (err) {
+                throw err;
+              }
+              image.toBuffer('jpg', {quality: 80}, function (err, buffer) {
+                if (err) {
+                  throw err;
+                }
+                assert.notStrictEqual(null, buffer);
+                deferred.resolve();
+              });
+            });
+          });
+        }
+      });
+    }
+    // mapnik
+    jpegSuite.add('mapnik-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        mapnik.Image.open(fixtures.inputJpg, function (err, img) {
+          if (err) throw err;
+          img
+            .resize(width, height, {
+              scaling_method: mapnik.imageScaling.lanczos
+            })
+            .save(fixtures.outputJpg, 'jpeg:quality=80', function (err) {
+              if (err) throw err;
+              deferred.resolve();
+            });
+        });
+      }
+    }).add('mapnik-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        mapnik.Image.fromBytes(inputJpgBuffer, function (err, img) {
+          if (err) throw err;
+          img
+            .resize(width, height, {
+              scaling_method: mapnik.imageScaling.lanczos
+            })
+            .encode('jpeg:quality=80', function (err) {
+              if (err) throw err;
+              deferred.resolve();
+            });
+        });
+      }
+    });
+    // imagemagick
+    jpegSuite.add('imagemagick-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        imagemagick.resize({
+          srcPath: fixtures.inputJpg,
+          dstPath: fixtures.outputJpg,
+          quality: 0.8,
+          width: width,
+          height: height,
+          format: 'jpg',
+          filter: 'Lanczos'
+        }, function (err) {
+          if (err) {
+            throw err;
+          } else {
+            deferred.resolve();
+          }
+        });
+      }
+    });
+    // imagemagick-native
+    if (typeof imagemagickNative !== 'undefined') {
+      jpegSuite.add('imagemagick-native-buffer-buffer', {
+        defer: true,
+        fn: function (deferred) {
+          imagemagickNative.convert({
+            srcData: inputJpgBuffer,
+            quality: 80,
+            width: width,
+            height: height,
+            format: 'JPEG',
+            filter: 'Lanczos'
+          }, function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+        }
+      });
+    }
+    // gm
+    jpegSuite.add('gm-buffer-file', {
+      defer: true,
+      fn: function (deferred) {
+        gm(inputJpgBuffer)
+          .filter('Lanczos')
+          .resize(width, height)
+          .quality(80)
+          .write(fixtures.outputJpg, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('gm-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        gm(inputJpgBuffer)
+          .filter('Lanczos')
+          .resize(width, height)
+          .quality(80)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('gm-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        gm(fixtures.inputJpg)
+          .filter('Lanczos')
+          .resize(width, height)
+          .quality(80)
+          .write(fixtures.outputJpg, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('gm-file-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        gm(fixtures.inputJpg)
+          .filter('Lanczos')
+          .resize(width, height)
+          .quality(80)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    });
+    // sharp
+    jpegSuite.add('sharp-buffer-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .toFile(fixtures.outputJpg, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputJpg)
+          .resize(width, height)
+          .toFile(fixtures.outputJpg, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-stream-stream', {
+      defer: true,
+      fn: function (deferred) {
+        const readable = fs.createReadStream(fixtures.inputJpg);
+        const writable = fs.createWriteStream(fixtures.outputJpg);
+        writable.on('finish', function () {
+          deferred.resolve();
+        });
+        const pipeline = sharp()
+          .resize(width, height);
+        readable.pipe(pipeline).pipe(writable);
+      }
+    }).add('sharp-file-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputJpg)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-promise', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .toBuffer()
+          .then(function (buffer) {
+            assert.notStrictEqual(null, buffer);
+            deferred.resolve();
+          });
+      }
+    }).on('cycle', function (event) {
+      console.log('jpeg ' + String(event.target));
+    }).on('complete', function () {
+      callback(null, this.filter('fastest').map('name'));
+    }).run();
+  },
+  // Effect of applying operations
+  operations: function (callback) {
+    const inputJpgBuffer = fs.readFileSync(fixtures.inputJpg);
+    const operationsSuite = new Benchmark.Suite('operations');
+    operationsSuite.add('sharp-sharpen-mild', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .sharpen()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-sharpen-radius', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .sharpen(3, 1, 3)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-blur-mild', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .blur()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-blur-radius', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .blur(3)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-gamma', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .gamma()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-normalise', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .normalise()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-greyscale', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .greyscale()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-greyscale-gamma', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .gamma()
+          .greyscale()
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-progressive', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .jpeg({ progressive: true })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-without-chroma-subsampling', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .jpeg({ chromaSubsampling: '4:4:4' })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-rotate', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .rotate(90)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-without-simd', {
+      defer: true,
+      fn: function (deferred) {
+        sharp.simd(false);
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            sharp.simd(true);
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-sequentialRead', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .sequentialRead()
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-crop-entropy', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .crop(sharp.strategy.entropy)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-crop-attention', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height)
+          .crop(sharp.strategy.attention)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).on('cycle', function (event) {
+      console.log('operations ' + String(event.target));
+    }).on('complete', function () {
+      callback(null, this.filter('fastest').map('name'));
+    }).run();
+  },
+  // Comparitive speed of kernels
+  kernels: function (callback) {
+    const inputJpgBuffer = fs.readFileSync(fixtures.inputJpg);
+    (new Benchmark.Suite('kernels')).add('sharp-cubic', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height, { kernel: 'cubic' })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-lanczos2', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height, { kernel: 'lanczos2' })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-lanczos3', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputJpgBuffer)
+          .resize(width, height, { kernel: 'lanczos3' })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).on('cycle', function (event) {
+      console.log('kernels ' + String(event.target));
+    }).on('complete', function () {
+      callback(null, this.filter('fastest').map('name'));
+    }).run();
+  },
+  // PNG
+  png: function (callback) {
+    const inputPngBuffer = fs.readFileSync(fixtures.inputPng);
+    const pngSuite = new Benchmark.Suite('png');
+    // jimp
+    pngSuite.add('jimp-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        jimp.read(inputPngBuffer, function (err, image) {
+          if (err) {
+            throw err;
+          } else {
+            image
+              .resize(width, height)
+              .getBuffer(jimp.MIME_PNG, function (err) {
+                if (err) {
+                  throw err;
+                } else {
+                  deferred.resolve();
+                }
+              });
+          }
+        });
+      }
+    }).add('jimp-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        jimp.read(fixtures.inputPng, function (err, image) {
+          if (err) {
+            throw err;
+          } else {
+            image
+              .resize(width, height)
+              .write(fixtures.outputPng, function (err) {
+                if (err) {
+                  throw err;
+                } else {
+                  deferred.resolve();
+                }
+              });
+          }
+        });
+      }
+    });
+    // lwip
+    if (typeof lwip !== 'undefined') {
+      pngSuite.add('lwip-buffer-buffer', {
+        defer: true,
+        fn: function (deferred) {
+          lwip.open(inputPngBuffer, 'png', function (err, image) {
+            if (err) {
+              throw err;
+            }
+            image.resize(width, height, 'lanczos', function (err, image) {
+              if (err) {
+                throw err;
+              }
+              image.toBuffer('png', function (err, buffer) {
+                if (err) {
+                  throw err;
+                }
+                assert.notStrictEqual(null, buffer);
+                deferred.resolve();
+              });
+            });
+          });
+        }
+      });
+    }
+    // mapnik
+    pngSuite.add('mapnik-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        mapnik.Image.open(fixtures.inputPng, function (err, img) {
+          if (err) throw err;
+          img.premultiply(function (err, img) {
+            if (err) throw err;
+            img.resize(width, height, {
+              scaling_method: mapnik.imageScaling.lanczos
+            }, function (err, img) {
+              if (err) throw err;
+              img.demultiply(function (err, img) {
+                if (err) throw err;
+                img.save(fixtures.outputPng, 'png', function (err) {
+                  if (err) throw err;
+                  deferred.resolve();
+                });
+              });
+            });
+          });
+        });
+      }
+    }).add('mapnik-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        mapnik.Image.fromBytes(inputPngBuffer, function (err, img) {
+          if (err) throw err;
+          img.premultiply(function (err, img) {
+            if (err) throw err;
+            img.resize(width, height, {
+              scaling_method: mapnik.imageScaling.lanczos
+            }, function (err, img) {
+              if (err) throw err;
+              img.demultiply(function (err, img) {
+                if (err) throw err;
+                img.encode('png', function (err) {
+                  if (err) throw err;
+                  deferred.resolve();
+                });
+              });
+            });
+          });
+        });
+      }
+    });
+    // imagemagick
+    pngSuite.add('imagemagick-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        imagemagick.resize({
+          srcPath: fixtures.inputPng,
+          dstPath: fixtures.outputPng,
+          width: width,
+          height: height,
+          filter: 'Lanczos'
+        }, function (err) {
+          if (err) {
+            throw err;
+          } else {
+            deferred.resolve();
+          }
+        });
+      }
+    });
+    // imagemagick-native
+    if (typeof imagemagickNative !== 'undefined') {
+      pngSuite.add('imagemagick-native-buffer-buffer', {
+        defer: true,
+        fn: function (deferred) {
+          imagemagickNative.convert({
+            srcData: inputPngBuffer,
+            width: width,
+            height: height,
+            format: 'PNG',
+            filter: 'Lanczos'
+          });
+          deferred.resolve();
+        }
+      });
+    }
+    // gm
+    pngSuite.add('gm-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        gm(fixtures.inputPng)
+          .filter('Lanczos')
+          .resize(width, height)
+          .write(fixtures.outputPng, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('gm-file-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        gm(fixtures.inputPng)
+          .filter('Lanczos')
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    });
+    // sharp
+    pngSuite.add('sharp-buffer-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputPngBuffer)
+          .resize(width, height)
+          .toFile(fixtures.outputPng, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputPngBuffer)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputPng)
+          .resize(width, height)
+          .toFile(fixtures.outputPng, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-file-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputPng)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-progressive', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputPngBuffer)
+          .resize(width, height)
+          .png({ progressive: true })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-withoutAdaptiveFiltering', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputPngBuffer)
+          .resize(width, height)
+          .png({ adaptiveFiltering: false })
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    });
+    pngSuite.on('cycle', function (event) {
+      console.log(' png ' + String(event.target));
+    }).on('complete', function () {
+      callback(null, this.filter('fastest').map('name'));
+    }).run();
+  },
+  // WebP
+  webp: function (callback) {
+    const inputWebPBuffer = fs.readFileSync(fixtures.inputWebP);
+    (new Benchmark.Suite('webp')).add('sharp-buffer-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputWebPBuffer)
+          .resize(width, height)
+          .toFile(fixtures.outputWebP, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-buffer-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputWebPBuffer)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-file-file', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputWebP)
+          .resize(width, height)
+          .toFile(fixtures.outputWebP, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              deferred.resolve();
+            }
+          });
+      }
+    }).add('sharp-file-buffer', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(fixtures.inputWebp)
+          .resize(width, height)
+          .toBuffer(function (err, buffer) {
+            if (err) {
+              throw err;
+            } else {
+              assert.notStrictEqual(null, buffer);
+              deferred.resolve();
+            }
+          });
+      }
+    }).on('cycle', function (event) {
+      console.log('webp ' + String(event.target));
+    }).on('complete', function () {
+      callback(null, this.filter('fastest').map('name'));
+    }).run();
+  }
+}, function (err, results) {
+  assert(!err, err);
+  Object.keys(results).forEach(function (format) {
+    if (results[format].toString().substr(0, 5) !== 'sharp') {
+      console.log('sharp was slower than ' + results[format] + ' for ' + format);
+    }
+  });
+  console.dir(sharp.cache());
+});

test/bench/random.js

@@ -0,0 +1,75 @@
+'use strict';
+
+const imagemagick = require('imagemagick');
+const gm = require('gm');
+const assert = require('assert');
+const Benchmark = require('benchmark');
+
+const sharp = require('../../');
+const fixtures = require('../fixtures');
+
+sharp.cache(false);
+sharp.simd(true);
+
+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) {
+    imagemagick.resize({
+      srcPath: fixtures.inputJpg,
+      dstPath: fixtures.outputJpg,
+      quality: 0.8,
+      width: randomDimension(),
+      height: randomDimension(),
+      format: 'jpg',
+      filter: 'Lanczos'
+    }, function (err) {
+      if (err) {
+        throw err;
+      } else {
+        deferred.resolve();
+      }
+    });
+  }
+}).add('gm', {
+  defer: true,
+  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();
+        }
+      });
+  }
+}).on('cycle', function (event) {
+  console.log(String(event.target));
+}).on('complete', function () {
+  const winner = this.filter('fastest').map('name');
+  assert.strictEqual('sharp', String(winner), 'sharp was slower than ' + winner);
+}).run();