Release v0.21.0

Remove lwip and images as they lack Node 10 support

.editorconfig

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

.gitattributes

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

.gitignore

@@ -1,17 +1,15 @@
-lib-cov
-*.seed
-*.log
-*.csv
-*.dat
-*.out
-*.pid
-*.gz
-
-pids
-logs
-results
 build
 node_modules
-tests/output.jpg
-
-npm-debug.log
+/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
+.gitattributes
+.DS_Store
+.nyc_output
+package-lock.json

.npmignore

@@ -0,0 +1,15 @@
+build
+node_modules
+coverage
+.editorconfig
+.gitattributes
+.gitignore
+test
+.travis.yml
+appveyor.yml
+mkdocs.yml
+docs/css/
+vendor
+.prebuildrc
+.nyc_output
+CONTRIBUTING.md

.prebuildrc

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

.travis.yml

@@ -1,8 +1,58 @@
-language: node_js
-node_js:
-  - "0.11"
-  - "0.10"
-before_install:
- - sudo apt-get update -qq
- - sudo apt-get install -qq libvips-dev imagemagick
- - sudo ln -s /usr/lib/pkgconfig/vips-7.26.pc /usr/lib/pkgconfig/vips.pc
+matrix:
+  include:
+    - name: "Linux (glibc) - Node 6"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "6"
+    - name: "Linux (glibc) - Node 8"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "8"
+    - name: "Linux (glibc) - Node 10"
+      os: linux
+      dist: trusty
+      sudo: false
+      language: node_js
+      node_js: "10"
+      after_success:
+        - npm install coveralls
+        - cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js
+    - name: "Linux (musl) - Node 8"
+      os: linux
+      dist: trusty
+      sudo: true
+      language: minimal
+      before_install:
+        - sudo docker run -dit --name sharp --env CI --env PREBUILD_TOKEN --volume "${PWD}:/mnt/sharp" --workdir /mnt/sharp node:8-alpine
+        - sudo docker exec sharp apk add build-base git python2 --update-cache
+      install: sudo docker exec sharp sh -c "npm install --unsafe-perm"
+      script: sudo docker exec sharp sh -c "npm test"
+    - name: "Linux (musl) - Node 10"
+      os: linux
+      dist: trusty
+      sudo: true
+      language: minimal
+      before_install:
+        - sudo docker run -dit --name sharp --env CI --env PREBUILD_TOKEN --volume "${PWD}:/mnt/sharp" --workdir /mnt/sharp node:10-alpine
+        - sudo docker exec sharp apk add build-base git python2 --update-cache
+      install: sudo docker exec sharp sh -c "npm install --unsafe-perm"
+      script: sudo docker exec sharp sh -c "npm test"
+    - name: "OS X - Node 6"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "6"
+    - name: "OS X - Node 8"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "8"
+    - name: "OS X - Node 10"
+      os: osx
+      osx_image: xcode9.2
+      language: node_js
+      node_js: "10"

CONTRIBUTING.md

@@ -0,0 +1,99 @@
+# Contributing to sharp
+
+Hello, thank you for your interest in helping!
+
+## Submit a new bug report
+
+Please create a [new issue](https://github.com/lovell/sharp/issues/new) containing the steps to reproduce the problem.
+
+If you're having installation problems, please include the output of running `npm install --verbose sharp`.
+
+New bugs are assigned a `triage` label whilst under investigation.
+
+## Submit a new feature request
+
+If a [similar request](https://github.com/lovell/sharp/labels/enhancement) exists, it's probably fastest to add a comment to it about your requirement.
+
+Implementation is usually straightforward if _libvips_ [already supports](https://libvips.github.io/libvips/API/current/) the feature you need.
+
+## Submit a Pull Request to fix a bug
+
+Thank you! To prevent the problem occurring again, please add unit tests that would have failed.
+
+Please select the `master` branch as the destination for your Pull Request so your fix can be included in the next minor release.
+
+Please squash your changes into a single commit using a command like `git rebase -i upstream/master`.
+
+To test C++ changes, you can compile the module using `npm install` and then run the tests using `npm test`.
+
+## Submit a Pull Request with a new feature
+
+Please add JavaScript [unit tests](https://github.com/lovell/sharp/tree/master/test/unit) to cover your new feature.
+A test coverage report for the JavaScript code is generated in the `coverage/lcov-report` directory.
+
+Where possible, the functional tests use gradient-based perceptual hashes
+based on [dHash](http://www.hackerfactor.com/blog/index.php?/archives/529-Kind-of-Like-That.html)
+to compare expected vs actual images.
+
+You deserve to add your details to the [list of contributors](https://github.com/lovell/sharp/blob/master/package.json#L5).
+
+Any change that modifies the existing public API should be added to the relevant work-in-progress branch for inclusion in the next major release.
+
+| Release | WIP branch |
+| ------: | :--------- |
+| v0.21.0 | teeth      |
+| v0.22.0 | uptake     |
+
+Please squash your changes into a single commit using a command like `git rebase -i upstream/<wip-branch>`.
+
+### Add a new public method
+
+The API tries to be as fluent as possible. Image processing concepts follow the naming conventions from _libvips_ and, to a lesser extent, _ImageMagick_.
+
+Most methods have optional parameters and assume sensible defaults. Methods with mandatory parameters often have names like `doSomethingWith(X)`.
+
+Please ensure backwards compatibility where possible. Methods to modify previously default behaviour often have names like `withoutOptionY()` or `withExtraZ()`.
+
+Feel free to create a [new issue](https://github.com/lovell/sharp/issues/new) to gather feedback on a potential API change.
+
+### Remove an existing public method
+
+A method to be removed should be deprecated in the next major version then removed in the following major version.
+
+By way of example, the [bilinearInterpolation method](https://github.com/lovell/sharp/blob/v0.6.0/index.js#L155) present in v0.5.0 was deprecated in v0.6.0 and removed in v0.7.0.
+
+## Documentation
+
+The public API is documented with [JSDoc](http://usejsdoc.org/) annotated comments.
+
+These can be converted to Markdown by running:
+```sh
+npm run docs
+```
+
+Please include documentation updates in any Pull Request that modifies the public API.
+
+## Run the tests
+
+### Functional tests and static code analysis
+
+```sh
+npm test
+```
+
+### Memory leak tests
+
+Requires [Valgrind](http://valgrind.org/).
+
+```sh
+npm run test-leak
+```
+
+## Finally
+
+Please feel free to ask any questions via a
+[new issue](https://github.com/lovell/sharp/issues/new).
+
+If you're unable to post details publicly, please
+[e-mail](https://github.com/lovell/sharp/blob/master/package.json#L4)
+for private, paid consulting.

README.md

@@ -1,96 +1,94 @@
 # sharp
 
-_adj_
-
-1. clearly defined; distinct: a sharp photographic image. 
-2. quick, brisk, or spirited. 
-3. shrewd or astute: a sharp bargainer. 
-4. (Informal.) very stylish: a sharp dresser; a sharp jacket. 
-
-The typical use case for this high performance Node.js module is to convert a large JPEG image to smaller JPEG images of varying dimensions.
-
-It is somewhat opinionated in that it only deals with JPEG images, always obeys the requested dimensions by either cropping or embedding and insists on a mild sharpen of the resulting image.
-
-Under the hood you'll find the blazingly fast [libvips](https://github.com/jcupitt/libvips) image processing library, originally created in 1989 at Birkbeck College and currently maintained by the University of Southampton.
-
-Speed is typically 4x faster than the imagemagick equivalent.
-
-## Prerequisites
-
-Requires node-gyp and libvips-dev to build.
-
-	sudo npm install -g node-gyp
-	sudo apt-get install libvips-dev
-
-Requires vips-7.xx.pc (installed with libvips-dev) to be symlinked as /usr/lib/pkgconfig/vips.pc
-
-Ubuntu 12.04 LTS:
-
-	sudo ln -s /usr/lib/pkgconfig/vips-7.26.pc /usr/lib/pkgconfig/vips.pc
-
-Ubuntu 13.04 (64-bit):
-
-	sudo ln -s /usr/lib/x86_64-linux-gnu/pkgconfig/vips-7.28.pc /usr/lib/pkgconfig/vips.pc
-
-## Install
-
-	npm install sharp
-
-## Usage
-
-  var sharp = require("sharp");
-
-### crop(inputPath, outputPath, width, height, callback)
-
-Scale and crop JPEG `inputPath` to `width` x `height` and write JPEG to `outputPath` calling `callback` when complete.
-
-Example:
-
-```javascript
-sharp.crop("input.jpg", "output.jpg", 300, 200, 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
-});
+```sh
+npm install sharp
 ```
 
-### embedWhite(inputPath, outputPath, width, height, callback)
-
-Scale and embed JPEG `inputPath` to `width` x `height` using a white canvas and write JPEG to `outputPath` calling `callback` when complete.
-
-```javascript
-sharp.embedWhite("input.jpg", "output.jpg", 200, 300, function(err) {
-  if (err) {
-    throw err;
-  }
-  // output.jpg is a 300 pixels wide and 200 pixels high image
-  // containing a scaled version of input.jpg embedded on a white canvas
-});
+```sh
+yarn add sharp
 ```
 
-### embedBlack(inputPath, outputPath, width, height, callback)
+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.
 
-Scale and embed JPEG `inputPath` to `width` x `height` using a black canvas and write JPEG to `outputPath` calling `callback` when complete.
+Resizing an image is typically 4x-5x faster than using the
+quickest ImageMagick and GraphicsMagick settings.
+
+Colour spaces, embedded ICC profiles and alpha transparency channels are all handled correctly.
+Lanczos resampling ensures quality is not sacrificed for speed.
+
+As well as image resizing, operations such as
+rotation, extraction, compositing and gamma correction are available.
+
+Most modern 64-bit OS X, Windows and Linux systems running
+Node versions 6, 8 and 10
+do not require any additional install or runtime dependencies.
+
+## Examples
 
 ```javascript
-sharp.embedBlack("input.jpg", "output.jpg", 200, 300, function(err) {
-  if (err) {
-    throw err;
-  }
-  // output.jpg is a 300 pixels wide and 200 pixels high image
-  // containing a scaled version of input.jpg embedded on a black canvas
-});
+const sharp = require('sharp');
 ```
 
-## Testing [![Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+```javascript
+sharp(inputBuffer)
+  .resize(320, 240)
+  .toFile('output.webp', (err, info) => ... );
+  // A Promises/A+ promise is returned when callback is not provided.
+```
 
-	npm test
+```javascript
+sharp('input.jpg')
+  .rotate()
+  .resize(200)
+  .toBuffer()
+  .then( data => ... )
+  .catch( err => ... );
+```
 
-## Performance
+```javascript
+const roundedCorners = Buffer.from(
+  '<svg><rect x="0" y="0" width="200" height="200" rx="50" ry="50"/></svg>'
+);
 
-Using an AMD Athlon quad core CPU with 512KB L2 cache clocked at 3.3GHz with 8GB RAM:
+const roundedCornerResizer =
+  sharp()
+    .resize(200, 200)
+    .overlayWith(roundedCorners, { cutout: true })
+    .png();
 
-* imagemagick x 5.55 ops/sec <20>0.68% (31 runs sampled)
-* sharp x 24.49 ops/sec <20>6.85% (64 runs sampled)
+readableStream
+  .pipe(roundedCornerResizer)
+  .pipe(writableStream);
+```
+
+[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.png?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
+
+### Documentation
+
+Visit [sharp.pixelplumbing.com](http://sharp.pixelplumbing.com/) for complete
+[installation instructions](http://sharp.pixelplumbing.com/page/install),
+[API documentation](http://sharp.pixelplumbing.com/page/api),
+[benchmark tests](http://sharp.pixelplumbing.com/page/performance) and
+[changelog](http://sharp.pixelplumbing.com/page/changelog).
+
+### Contributing
+
+A [guide for contributors](https://github.com/lovell/sharp/blob/master/CONTRIBUTING.md)
+covers reporting bugs, requesting features and submitting code changes.
+
+### Licensing
+
+Copyright 2013, 2014, 2015, 2016, 2017, 2018 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.

appveyor.yml

@@ -0,0 +1,15 @@
+os: Visual Studio 2015
+version: "{build}"
+build: off
+platform: x64
+environment:
+  matrix:
+  - nodejs_version: "6"
+  - nodejs_version: "8"
+  - nodejs_version: "10"
+install:
+  - ps: Install-Product node $env:nodejs_version x64
+  - npm install -g npm@5
+  - npm install
+test_script:
+  - npm test

binding.gyp

@@ -1,14 +1,197 @@
 {
   'targets': [{
+    'target_name': 'libvips-cpp',
+    'conditions': [
+      ['OS == "win"', {
+        # Build libvips C++ binding for Windows due to MSVC std library ABI changes
+        'type': 'shared_library',
+        'defines': [
+          'VIPS_CPLUSPLUS_EXPORTS',
+          '_ALLOW_KEYWORD_MACROS'
+        ],
+        'sources': [
+          'src/libvips/cplusplus/VError.cpp',
+          'src/libvips/cplusplus/VInterpolate.cpp',
+          'src/libvips/cplusplus/VImage.cpp'
+        ],
+        'include_dirs': [
+          'vendor/include',
+          'vendor/include/glib-2.0',
+          'vendor/lib/glib-2.0/include'
+        ],
+        'libraries': [
+          '../vendor/lib/libvips.lib',
+          '../vendor/lib/libglib-2.0.lib',
+          '../vendor/lib/libgobject-2.0.lib'
+        ],
+        'configurations': {
+          'Release': {
+            'msvs_settings': {
+              'VCCLCompilerTool': {
+                'ExceptionHandling': 1
+              }
+            },
+            'msvs_disabled_warnings': [
+              4275
+            ]
+          }
+        }
+      }, {
+        # Ignore this target for non-Windows
+        'type': 'none'
+      }]
+    ]
+  }, {
     'target_name': 'sharp',
-    'sources': ['src/sharp.cc'],
-    'libraries': ['<!@(PKG_CONFIG_PATH="/usr/lib/pkgconfig" pkg-config --libs glib-2.0 vips)'],
-    'include_dirs': [
-      '/usr/include/glib-2.0',
-      '/usr/lib/glib-2.0/include',
-      '/usr/lib/x86_64-linux-gnu/glib-2.0/include'
+    'dependencies': [
+      'libvips-cpp'
     ],
-    'cflags': ['-fexceptions'],
-    'cflags_cc': ['-fexceptions']
+    'variables': {
+      'runtime_link%': 'shared',
+      'conditions': [
+        ['OS != "win"', {
+          'pkg_config_path': '<!(node -e "console.log(require(\'./lib/libvips\').pkgConfigPath())")',
+          'use_global_libvips': '<!(node -e "console.log(Boolean(require(\'./lib/libvips\').useGlobalLibvips()).toString())")'
+        }, {
+          'pkg_config_path': '',
+          'use_global_libvips': ''
+        }]
+      ]
+    },
+    'sources': [
+      'src/common.cc',
+      'src/metadata.cc',
+      'src/stats.cc',
+      'src/operations.cc',
+      'src/pipeline.cc',
+      'src/sharp.cc',
+      'src/utilities.cc'
+    ],
+    'include_dirs': [
+      '<!(node -e "require(\'nan\')")'
+    ],
+    'conditions': [
+      ['use_global_libvips == "true"', {
+        # Use pkg-config for include and lib
+        'include_dirs': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --cflags-only-I vips-cpp vips glib-2.0 | sed s\/-I//g)'],
+        'conditions': [
+          ['runtime_link == "static"', {
+            'libraries': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --libs --static vips-cpp)']
+          }, {
+            'libraries': ['<!@(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --libs vips-cpp)']
+          }],
+          ['OS == "linux"', {
+            'defines': [
+              # Inspect libvips-cpp.so to determine which C++11 ABI version was used and set _GLIBCXX_USE_CXX11_ABI accordingly. This is quite horrible.
+              '_GLIBCXX_USE_CXX11_ABI=<!(if readelf -Ws "$(PKG_CONFIG_PATH="<(pkg_config_path)" pkg-config --variable libdir vips-cpp)/libvips-cpp.so" | c++filt | grep -qF __cxx11;then echo "1";else echo "0";fi)'
+            ]
+          }]
+        ]
+      }, {
+        # Use pre-built libvips stored locally within node_modules
+        'include_dirs': [
+          'vendor/include',
+          'vendor/include/glib-2.0',
+          'vendor/lib/glib-2.0/include'
+        ],
+        'conditions': [
+          ['OS == "win"', {
+            'defines': [
+              '_ALLOW_KEYWORD_MACROS'
+            ],
+            'libraries': [
+              '../vendor/lib/libvips.lib',
+              '../vendor/lib/libglib-2.0.lib',
+              '../vendor/lib/libgobject-2.0.lib'
+            ]
+          }],
+          ['OS == "mac"', {
+            'libraries': [
+              '../vendor/lib/libvips-cpp.42.dylib',
+              '../vendor/lib/libvips.42.dylib',
+              '../vendor/lib/libglib-2.0.0.dylib',
+              '../vendor/lib/libgobject-2.0.0.dylib',
+              # Ensure runtime linking is relative to sharp.node
+              '-rpath \'@loader_path/../../vendor/lib\''
+            ]
+          }],
+          ['OS == "linux"', {
+            'defines': [
+              '_GLIBCXX_USE_CXX11_ABI=0'
+            ],
+            'libraries': [
+              '../vendor/lib/libvips-cpp.so',
+              '../vendor/lib/libvips.so',
+              '../vendor/lib/libglib-2.0.so',
+              '../vendor/lib/libgobject-2.0.so',
+              # Dependencies of dependencies, included for openSUSE support
+              '../vendor/lib/libcairo.so',
+              '../vendor/lib/libcroco-0.6.so',
+              '../vendor/lib/libexif.so',
+              '../vendor/lib/libexpat.so',
+              '../vendor/lib/libffi.so',
+              '../vendor/lib/libfontconfig.so',
+              '../vendor/lib/libfreetype.so',
+              '../vendor/lib/libfribidi.so',
+              '../vendor/lib/libgdk_pixbuf-2.0.so',
+              '../vendor/lib/libgif.so',
+              '../vendor/lib/libgio-2.0.so',
+              '../vendor/lib/libgmodule-2.0.so',
+              '../vendor/lib/libgsf-1.so',
+              '../vendor/lib/libgthread-2.0.so',
+              '../vendor/lib/libharfbuzz.so',
+              '../vendor/lib/libharfbuzz-subset.so.0',
+              '../vendor/lib/libjpeg.so',
+              '../vendor/lib/liblcms2.so',
+              '../vendor/lib/liborc-0.4.so',
+              '../vendor/lib/libpango-1.0.so',
+              '../vendor/lib/libpangocairo-1.0.so',
+              '../vendor/lib/libpangoft2-1.0.so',
+              '../vendor/lib/libpixman-1.so',
+              '../vendor/lib/libpng.so',
+              '../vendor/lib/librsvg-2.so',
+              '../vendor/lib/libtiff.so',
+              '../vendor/lib/libwebp.so',
+              '../vendor/lib/libwebpdemux.so',
+              '../vendor/lib/libwebpmux.so',
+              '../vendor/lib/libxml2.so',
+              '../vendor/lib/libz.so',
+              # Ensure runtime linking is relative to sharp.node
+              '-Wl,--disable-new-dtags -Wl,-rpath=\'$${ORIGIN}/../../vendor/lib\''
+            ]
+          }]
+        ]
+      }]
+    ],
+    'cflags_cc': [
+      '-std=c++0x',
+      '-fexceptions',
+      '-Wall',
+      '-O3'
+    ],
+    'xcode_settings': {
+      'CLANG_CXX_LANGUAGE_STANDARD': 'c++11',
+      'CLANG_CXX_LIBRARY': 'libc++',
+      'MACOSX_DEPLOYMENT_TARGET': '10.7',
+      'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
+      'GCC_ENABLE_CPP_RTTI': 'YES',
+      'OTHER_CPLUSPLUSFLAGS': [
+        '-fexceptions',
+        '-Wall',
+        '-O3'
+      ]
+    },
+    'configurations': {
+      'Release': {
+        'msvs_settings': {
+          'VCCLCompilerTool': {
+            'ExceptionHandling': 1
+          }
+        },
+        'msvs_disabled_warnings': [
+          4275
+        ]
+      }
+    },
   }]
 }

docs/api-channel.md

@@ -0,0 +1,99 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## removeAlpha
+
+Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
+
+### Examples
+
+```javascript
+sharp('rgba.png')
+  .removeAlpha()
+  .toFile('rgb.png', function(err, info) {
+    // rgb.png is a 3 channel image without an alpha channel
+  });
+```
+
+Returns **Sharp** 
+
+## extractChannel
+
+Extract a single channel from a multi-channel image.
+
+### Parameters
+
+-   `channel` **([Number][1] \| [String][2])** zero-indexed band number to extract, or `red`, `green` or `blue` as alternative to `0`, `1` or `2` respectively.
+
+### Examples
+
+```javascript
+sharp(input)
+  .extractChannel('green')
+  .toFile('input_green.jpg', function(err, info) {
+    // info.channels === 1
+    // input_green.jpg contains the green channel of the input image
+   });
+```
+
+-   Throws **[Error][3]** Invalid channel
+
+Returns **Sharp** 
+
+## joinChannel
+
+Join one or more channels to the image.
+The meaning of the added channels depends on the output colourspace, set with `toColourspace()`.
+By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+Channel ordering follows vips convention:
+
+-   sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha.
+-   CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha.
+
+Buffers may be any of the image formats supported by sharp: JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data.
+For raw pixel input, the `options` object should contain a `raw` attribute, which follows the format of the attribute of the same name in the `sharp()` constructor.
+
+### Parameters
+
+-   `images` **([Array][4]&lt;([String][2] \| [Buffer][5])> | [String][2] \| [Buffer][5])** one or more images (file paths, Buffers).
+-   `options` **[Object][6]** image options, see `sharp()` constructor.
+
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+## bandbool
+
+Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.
+
+### Parameters
+
+-   `boolOp` **[String][2]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+
+### Examples
+
+```javascript
+sharp('3-channel-rgb-input.png')
+  .bandbool(sharp.bool.and)
+  .toFile('1-channel-output.png', function (err, info) {
+    // The output will be a single channel image where each pixel `P = R & G & B`.
+    // If `I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111]`
+    // then `O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2`.
+  });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[5]: https://nodejs.org/api/buffer.html
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

docs/api-colour.md

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

docs/api-composite.md

@@ -0,0 +1,68 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## 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`.
+
+If the overlay image contains an alpha channel then composition with premultiplication will occur.
+
+### Parameters
+
+-   `overlay` **([Buffer][1] \| [String][2])** Buffer containing image data or String containing the path to an image file.
+-   `options` **[Object][3]?** 
+    -   `options.gravity` **[String][2]** gravity at which to place the overlay. (optional, default `'centre'`)
+    -   `options.top` **[Number][4]?** the pixel offset from the top edge.
+    -   `options.left` **[Number][4]?** the pixel offset from the left edge.
+    -   `options.tile` **[Boolean][5]** set to true to repeat the overlay image across the entire image with the given `gravity`. (optional, default `false`)
+    -   `options.cutout` **[Boolean][5]** 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.density` **[Number][4]** number representing the DPI for vector overlay image. (optional, default `72`)
+    -   `options.raw` **[Object][3]?** describes overlay when using raw pixel data.
+        -   `options.raw.width` **[Number][4]?** 
+        -   `options.raw.height` **[Number][4]?** 
+        -   `options.raw.channels` **[Number][4]?** 
+    -   `options.create` **[Object][3]?** describes a blank overlay to be created.
+        -   `options.create.width` **[Number][4]?** 
+        -   `options.create.height` **[Number][4]?** 
+        -   `options.create.channels` **[Number][4]?** 3-4
+        -   `options.create.background` **([String][2] \| [Object][3])?** parsed by the [color][6] module to extract values for red, green, blue and alpha.
+
+### Examples
+
+```javascript
+sharp('input.png')
+  .rotate(180)
+  .resize(300)
+  .flatten()
+  .background('#ff6600')
+  .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
+  .sharpen()
+  .withMetadata()
+  .webp( { quality: 90 } )
+  .toBuffer()
+  .then(function(outputBuffer) {
+    // outputBuffer contains upside down, 300px wide, alpha channel flattened
+    // onto orange background, composited with overlay.png with SE gravity,
+    // sharpened, with metadata, 90% quality WebP image data. Phew!
+  });
+```
+
+-   Throws **[Error][7]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://nodejs.org/api/buffer.html
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[6]: https://www.npmjs.org/package/color
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-constructor.md

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

docs/api-input.md

@@ -0,0 +1,148 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## clone
+
+Take a "snapshot" of the Sharp instance, returning a new instance.
+Cloned instances inherit the input of their parent instance.
+This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.
+
+### Examples
+
+```javascript
+const pipeline = sharp().rotate();
+pipeline.clone().resize(800, 600).pipe(firstWritableStream);
+pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
+readableStream.pipe(pipeline);
+// firstWritableStream receives auto-rotated, resized readableStream
+// secondWritableStream receives auto-rotated, extracted region of readableStream
+```
+
+Returns **Sharp** 
+
+## metadata
+
+Fast access to (uncached) image metadata without decoding any compressed image data.
+A 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`
+-   `size`: Total size of image in bytes, for Stream and Buffer input only
+-   `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
+-   `height`: Number of pixels high (EXIF orientation is not taken into consideration)
+-   `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][1]
+-   `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+-   `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...][2]
+-   `density`: Number of pixels per inch (DPI), if present
+-   `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
+-   `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+-   `hasProfile`: Boolean indicating the presence of an embedded ICC profile
+-   `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
+-   `orientation`: Number value of the EXIF Orientation header, if present
+-   `exif`: Buffer containing raw EXIF data, if present
+-   `icc`: Buffer containing raw [ICC][3] profile data, if present
+-   `iptc`: Buffer containing raw IPTC data, if present
+-   `xmp`: Buffer containing raw XMP data, if present
+
+### Parameters
+
+-   `callback` **[Function][4]?** called with the arguments `(err, metadata)`
+
+### Examples
+
+```javascript
+const image = sharp(inputJpg);
+image
+  .metadata()
+  .then(function(metadata) {
+    return image
+      .resize(Math.round(metadata.width / 2))
+      .webp()
+      .toBuffer();
+  })
+  .then(function(data) {
+    // data contains a WebP image half the width and height of the original JPEG
+  });
+```
+
+Returns **([Promise][5]&lt;[Object][6]> | Sharp)** 
+
+## stats
+
+Access to pixel-derived image statistics for every channel in the image.
+A Promise is returned when `callback` is not provided.
+
+-   `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
+    -   `min` (minimum value in the channel)
+    -   `max` (maximum value in the channel)
+    -   `sum` (sum of all values in a channel)
+    -   `squaresSum` (sum of squared values in a channel)
+    -   `mean` (mean of the values in a channel)
+    -   `stdev` (standard deviation for the values in a channel)
+    -   `minX` (x-coordinate of one of the pixel where the minimum lies)
+    -   `minY` (y-coordinate of one of the pixel where the minimum lies)
+    -   `maxX` (x-coordinate of one of the pixel where the maximum lies)
+    -   `maxY` (y-coordinate of one of the pixel where the maximum lies)
+-   `isOpaque`: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel
+-   `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
+
+### Parameters
+
+-   `callback` **[Function][4]?** called with the arguments `(err, stats)`
+
+### Examples
+
+```javascript
+const image = sharp(inputJpg);
+image
+  .stats()
+  .then(function(stats) {
+     // stats contains the channel-wise statistics array and the isOpaque value
+  });
+```
+
+Returns **[Promise][5]&lt;[Object][6]>** 
+
+## limitInputPixels
+
+Do not process input images where the number of pixels (width _ 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][7] \| [Boolean][8])** an integral Number of pixels, zero or false to remove limit, true to use default limit.
+
+
+-   Throws **[Error][9]** Invalid limit
+
+Returns **Sharp** 
+
+## sequentialRead
+
+An advanced setting that switches the libvips access method to `VIPS_ACCESS_SEQUENTIAL`.
+This will reduce memory usage and can improve performance on some systems.
+
+The default behaviour _before_ function call is `false`, meaning the libvips access method is not sequential.
+
+### Parameters
+
+-   `sequentialRead` **[Boolean][8]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+[1]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636
+
+[2]: https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672
+
+[3]: https://www.npmjs.com/package/icc
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-operation.md

@@ -0,0 +1,271 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## rotate
+
+Rotate the output image by either an explicit angle
+or auto-orient based on the EXIF `Orientation` tag.
+
+If an angle is provided, it is converted to a valid positive degree rotation.
+For example, `-450` will produce a 270deg rotation.
+
+When rotating by an angle other than a multiple of 90,
+the background colour can be provided with the `background` option.
+
+If no angle is provided, it is determined from the EXIF data.
+Mirroring is supported and may infer the use of a flip operation.
+
+The use of `rotate` implies the removal of the EXIF `Orientation` tag, if any.
+
+Method order is important when both rotating and extracting regions,
+for example `rotate(x).extract(y)` will produce a different result to `extract(y).rotate(x)`.
+
+### Parameters
+
+-   `angle` **[Number][1]** angle of rotation. (optional, default `auto`)
+-   `options` **[Object][2]?** if present, is an Object with optional attributes.
+    -   `options.background` **([String][3] \| [Object][2])** parsed by the [color][4] module to extract values for red, green, blue and alpha. (optional, default `"#000000"`)
+
+### Examples
+
+```javascript
+const pipeline = sharp()
+  .rotate()
+  .resize(null, 200)
+  .toBuffer(function (err, outputBuffer, info) {
+    // outputBuffer contains 200px high JPEG image data,
+    // auto-rotated using EXIF Orientation tag
+    // info.width and info.height contain the dimensions of the resized image
+  });
+readableStream.pipe(pipeline);
+```
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## flip
+
+Flip the image about the vertical Y axis. This always occurs after rotation, if any.
+The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.
+
+### Parameters
+
+-   `flip` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## flop
+
+Flop the image about the horizontal X axis. This always occurs after rotation, if any.
+The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.
+
+### Parameters
+
+-   `flop` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## sharpen
+
+Sharpen the image.
+When used without parameters, performs a fast, mild sharpen of the output image.
+When a `sigma` is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space.
+Separate control over the level of sharpening in "flat" and "jagged" areas is available.
+
+### Parameters
+
+-   `sigma` **[Number][1]?** the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+-   `flat` **[Number][1]** the level of sharpening to apply to "flat" areas. (optional, default `1.0`)
+-   `jagged` **[Number][1]** the level of sharpening to apply to "jagged" areas. (optional, default `2.0`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## median
+
+Apply median filter.
+When used without parameters the default window is 3x3.
+
+### Parameters
+
+-   `size` **[Number][1]** square mask size: size x size (optional, default `3`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## blur
+
+Blur the image.
+When used without parameters, performs a fast, mild blur of the output image.
+When a `sigma` is provided, performs a slower, more accurate Gaussian blur.
+
+### Parameters
+
+-   `sigma` **[Number][1]?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## flatten
+
+Merge alpha transparency channel, if any, with a background.
+
+### Parameters
+
+-   `options`  
+
+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][1]** value between 1.0 and 3.0. (optional, default `2.2`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## negate
+
+Produce the "negative" of the image.
+
+### Parameters
+
+-   `negate` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalise
+
+Enhance output image contrast by stretching its luminance to cover the full dynamic range.
+
+### Parameters
+
+-   `normalise` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## normalize
+
+Alternative spelling of normalise.
+
+### Parameters
+
+-   `normalize` **[Boolean][6]**  (optional, default `true`)
+
+Returns **Sharp** 
+
+## convolve
+
+Convolve the image with the specified kernel.
+
+### Parameters
+
+-   `kernel` **[Object][2]** 
+    -   `kernel.width` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.height` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.kernel` **[Array][7]&lt;[Number][1]>** Array of length `width*height` containing the kernel values.
+    -   `kernel.scale` **[Number][1]** the scale of the kernel in pixels. (optional, default `sum`)
+    -   `kernel.offset` **[Number][1]** the offset of the kernel in pixels. (optional, default `0`)
+
+### Examples
+
+```javascript
+sharp(input)
+  .convolve({
+    width: 3,
+    height: 3,
+    kernel: [-1, 0, 1, -2, 0, 2, -1, 0, 1]
+  })
+  .raw()
+  .toBuffer(function(err, data, info) {
+    // data contains the raw pixel data representing the convolution
+    // of the input image with the horizontal Sobel operator
+  });
+```
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## threshold
+
+Any pixel value greather than or equal to the threshold value will be set to 255, otherwise it will be set to 0.
+
+### Parameters
+
+-   `threshold` **[Number][1]** a value in the range 0-255 representing the level at which the threshold will be applied. (optional, default `128`)
+-   `options` **[Object][2]?** 
+    -   `options.greyscale` **[Boolean][6]** convert to single channel greyscale. (optional, default `true`)
+    -   `options.grayscale` **[Boolean][6]** alternative spelling for greyscale. (optional, default `true`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## boolean
+
+Perform a bitwise boolean operation with operand image.
+
+This operation creates an output image where each pixel is the result of
+the selected bitwise boolean `operation` between the corresponding pixels of the input images.
+
+### Parameters
+
+-   `operand` **([Buffer][8] \| [String][3])** Buffer containing image data or String containing the path to an image file.
+-   `operator` **[String][3]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+-   `options` **[Object][2]?** 
+    -   `options.raw` **[Object][2]?** describes operand when using raw pixel data.
+        -   `options.raw.width` **[Number][1]?** 
+        -   `options.raw.height` **[Number][1]?** 
+        -   `options.raw.channels` **[Number][1]?** 
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+## linear
+
+Apply the linear formula a \* input + b to the image (levels adjustment)
+
+### Parameters
+
+-   `a` **[Number][1]** multiplier (optional, default `1.0`)
+-   `b` **[Number][1]** offset (optional, default `0.0`)
+
+
+-   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[4]: https://www.npmjs.org/package/color
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
+
+[8]: https://nodejs.org/api/buffer.html

docs/api-output.md

@@ -0,0 +1,317 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## toFile
+
+Write output image data to a file.
+
+If an explicit output format is not selected, it will be inferred from the extension,
+with JPEG, PNG, WebP, TIFF, DZI, and libvips' V format supported.
+Note that raw pixel data is only supported for buffer output.
+
+A `Promise` is returned when `callback` is not provided.
+
+### Parameters
+
+-   `fileOut` **[String][1]** the path to write the image data to.
+-   `callback` **[Function][2]?** called on completion with two arguments `(err, info)`.
+    `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+    `channels` and `premultiplied` (indicating if premultiplication was used).
+    When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+
+### Examples
+
+```javascript
+sharp(input)
+  .toFile('output.png', (err, info) => { ... });
+```
+
+```javascript
+sharp(input)
+  .toFile('output.png')
+  .then(info => { ... })
+  .catch(err => { ... });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **[Promise][4]&lt;[Object][5]>** when no callback is provided
+
+## toBuffer
+
+Write output to a Buffer.
+JPEG, PNG, WebP, TIFF and RAW output are supported.
+By default, the format will match the input image, except GIF and SVG input which become PNG output.
+
+`callback`, if present, gets three arguments `(err, data, info)` where:
+
+-   `err` is an error, if any.
+-   `data` is the output image data.
+-   `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+    `channels` and `premultiplied` (indicating if premultiplication was used).
+    When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+
+A `Promise` is returned when `callback` is not provided.
+
+### Parameters
+
+-   `options` **[Object][5]?** 
+    -   `options.resolveWithObject` **[Boolean][6]?** Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
+-   `callback` **[Function][2]?** 
+
+### Examples
+
+```javascript
+sharp(input)
+  .toBuffer((err, data, info) => { ... });
+```
+
+```javascript
+sharp(input)
+  .toBuffer()
+  .then(data => { ... })
+  .catch(err => { ... });
+```
+
+```javascript
+sharp(input)
+  .toBuffer({ resolveWithObject: true })
+  .then(({ data, info }) => { ... })
+  .catch(err => { ... });
+```
+
+Returns **[Promise][4]&lt;[Buffer][7]>** when no callback is provided
+
+## withMetadata
+
+Include all metadata (EXIF, XMP, IPTC) from the input image in the output image.
+The default behaviour, when `withMetadata` is not used, is to strip all metadata and convert to the device-independent sRGB colour space.
+This will also convert to and add a web-friendly sRGB ICC profile.
+
+### Parameters
+
+-   `withMetadata` **[Object][5]?** 
+    -   `withMetadata.orientation` **[Number][8]?** value between 1 and 8, used to update the EXIF `Orientation` tag.
+
+### Examples
+
+```javascript
+sharp('input.jpg')
+  .withMetadata()
+  .toFile('output-with-metadata.jpg')
+  .then(info => { ... });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+## jpeg
+
+Use these JPEG options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
+    -   `options.chromaSubsampling` **[String][1]** set to '4:4:4' to prevent chroma subsampling when quality &lt;= 90 (optional, default `'4:2:0'`)
+    -   `options.trellisQuantisation` **[Boolean][6]** apply trellis quantisation, requires mozjpeg (optional, default `false`)
+    -   `options.overshootDeringing` **[Boolean][6]** apply overshoot deringing, requires mozjpeg (optional, default `false`)
+    -   `options.optimiseScans` **[Boolean][6]** optimise progressive scans, forces progressive, requires mozjpeg (optional, default `false`)
+    -   `options.optimizeScans` **[Boolean][6]** alternative spelling of optimiseScans (optional, default `false`)
+    -   `options.optimiseCoding` **[Boolean][6]** optimise Huffman coding tables (optional, default `true`)
+    -   `options.optimizeCoding` **[Boolean][6]** alternative spelling of optimiseCoding (optional, default `true`)
+    -   `options.quantisationTable` **[Number][8]** quantization table to use, integer 0-8, requires mozjpeg (optional, default `0`)
+    -   `options.quantizationTable` **[Number][8]** alternative spelling of quantisationTable (optional, default `0`)
+    -   `options.force` **[Boolean][6]** force JPEG output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to very high quality JPEG output
+const data = await sharp(input)
+  .jpeg({
+    quality: 100,
+    chromaSubsampling: '4:4:4'
+  })
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## png
+
+Use these PNG options for output image.
+
+PNG output is always full colour at 8 or 16 bits per pixel.
+Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.
+
+### Parameters
+
+-   `options` **[Object][5]?** 
+    -   `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
+    -   `options.compressionLevel` **[Number][8]** zlib compression level, 0-9 (optional, default `9`)
+    -   `options.adaptiveFiltering` **[Boolean][6]** use adaptive row filtering (optional, default `false`)
+    -   `options.force` **[Boolean][6]** force PNG output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to PNG output
+const data = await sharp(input)
+  .png()
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## webp
+
+Use these WebP options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.alphaQuality` **[Number][8]** quality of alpha layer, integer 0-100 (optional, default `100`)
+    -   `options.lossless` **[Boolean][6]** use lossless compression mode (optional, default `false`)
+    -   `options.nearLossless` **[Boolean][6]** use near_lossless compression mode (optional, default `false`)
+    -   `options.force` **[Boolean][6]** force WebP output, otherwise attempt to use input format (optional, default `true`)
+
+### Examples
+
+```javascript
+// Convert any input to lossless WebP output
+const data = await sharp(input)
+  .webp({ lossless: true })
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## tiff
+
+Use these TIFF options for output image.
+
+### Parameters
+
+-   `options` **[Object][5]?** output options
+    -   `options.quality` **[Number][8]** quality, integer 1-100 (optional, default `80`)
+    -   `options.force` **[Boolean][6]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
+    -   `options.compression` **[Boolean][6]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
+    -   `options.predictor` **[Boolean][6]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
+    -   `options.xres` **[Number][8]** horizontal resolution in pixels/mm (optional, default `1.0`)
+    -   `options.yres` **[Number][8]** vertical resolution in pixels/mm (optional, default `1.0`)
+    -   `options.squash` **[Boolean][6]** squash 8-bit images down to 1 bit (optional, default `false`)
+
+### Examples
+
+```javascript
+// Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
+sharp('input.svg')
+  .tiff({
+    compression: 'lzw',
+    squash: true
+  })
+  .toFile('1-bpp-output.tiff')
+  .then(info => { ... });
+```
+
+-   Throws **[Error][3]** Invalid options
+
+Returns **Sharp** 
+
+## raw
+
+Force output to be raw, uncompressed uint8 pixel data.
+
+### Examples
+
+```javascript
+// Extract raw RGB pixel data from JPEG input
+const { data, info } = await sharp('input.jpg')
+  .raw()
+  .toBuffer({ resolveWithObject: true });
+```
+
+Returns **Sharp** 
+
+## toFormat
+
+Force output to a given format.
+
+### Parameters
+
+-   `format` **([String][1] \| [Object][5])** as a String or an Object with an 'id' attribute
+-   `options` **[Object][5]** output options
+
+### Examples
+
+```javascript
+// Convert any input to PNG output
+const data = await sharp(input)
+  .toFormat('png')
+  .toBuffer();
+```
+
+-   Throws **[Error][3]** unsupported format or options
+
+Returns **Sharp** 
+
+## tile
+
+Use tile-based deep zoom (image pyramid) output.
+Set the format and options for tile images via the `toFormat`, `jpeg`, `png` or `webp` functions.
+Use a `.zip` or `.szi` file extension with `toFile` to write to a compressed archive file format.
+
+Warning: multiple sharp instances concurrently producing tile output can expose a possible race condition in some versions of libgsf.
+
+### Parameters
+
+-   `tile` **[Object][5]?** 
+    -   `tile.size` **[Number][8]** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
+    -   `tile.overlap` **[Number][8]** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
+    -   `tile.angle` **[Number][8]** tile angle of rotation, must be a multiple of 90. (optional, default `0`)
+    -   `tile.depth` **[String][1]?** how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
+    -   `tile.container` **[String][1]** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
+    -   `tile.layout` **[String][1]** filesystem layout, possible values are `dz`, `zoomify` or `google`. (optional, default `'dz'`)
+
+### Examples
+
+```javascript
+sharp('input.tiff')
+  .png()
+  .tile({
+    size: 512
+  })
+  .toFile('output.dz', function(err, info) {
+    // output.dzi is the Deep Zoom XML definition
+    // output_files contains 512x512 tiles grouped by zoom level
+  });
+```
+
+-   Throws **[Error][3]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
+
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
+
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[7]: https://nodejs.org/api/buffer.html
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

docs/api-resize.md

@@ -0,0 +1,232 @@
+<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
+
+## resize
+
+Resize image to `width`, `height` or `width x height`.
+
+When both a `width` and `height` are provided, the possible methods by which the image should **fit** these are:
+
+-   `cover`: Crop to cover both provided dimensions (the default).
+-   `contain`: Embed within both provided dimensions.
+-   `fill`: Ignore the aspect ratio of the input and stretch to both provided dimensions.
+-   `inside`: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to both those specified.
+-   `outside`: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to both those specified.
+    Some of these values are based on the [object-fit][1] CSS property.
+
+When using a `fit` of `cover` or `contain`, the default **position** is `centre`. Other options are:
+
+-   `sharp.position`: `top`, `right top`, `right`, `right bottom`, `bottom`, `left bottom`, `left`, `left top`.
+-   `sharp.gravity`: `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` or `centre`.
+-   `sharp.strategy`: `cover` only, dynamically crop using either the `entropy` or `attention` strategy.
+    Some of these values are based on the [object-position][2] CSS property.
+
+The experimental strategy-based approach resizes so one dimension is at its target length
+then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.
+
+-   `entropy`: focus on the region with the highest [Shannon entropy][3].
+-   `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.
+
+Possible interpolation kernels are:
+
+-   `nearest`: Use [nearest neighbour interpolation][4].
+-   `cubic`: Use a [Catmull-Rom spline][5].
+-   `lanczos2`: Use a [Lanczos kernel][6] with `a=2`.
+-   `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
+
+### Parameters
+
+-   `width` **[Number][7]?** pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
+-   `height` **[Number][7]?** pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
+-   `options` **[Object][8]?** 
+    -   `options.width` **[String][9]?** alternative means of specifying `width`. If both are present this take priority.
+    -   `options.height` **[String][9]?** alternative means of specifying `height`. If both are present this take priority.
+    -   `options.fit` **[String][9]** how the image should be resized to fit both provided dimensions, one of `cover`, `contain`, `fill`, `inside` or `outside`. (optional, default `'cover'`)
+    -   `options.position` **[String][9]** position, gravity or strategy to use when `fit` is `cover` or `contain`. (optional, default `'centre'`)
+    -   `options.background` **([String][9] \| [Object][8])** background colour when using a `fit` of `contain`, parsed by the [color][10] module, defaults to black without transparency. (optional, default `{r:0,g:0,b:0,alpha:1}`)
+    -   `options.kernel` **[String][9]** the kernel to use for image reduction. (optional, default `'lanczos3'`)
+    -   `options.withoutEnlargement` **[Boolean][11]** do not enlarge if the width _or_ height are already less than the specified dimensions, equivalent to GraphicsMagick's `>` geometry option. (optional, default `false`)
+    -   `options.fastShrinkOnLoad` **[Boolean][11]** take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images. (optional, default `true`)
+
+### Examples
+
+```javascript
+sharp(input)
+  .resize({ width: 100 })
+  .toBuffer()
+  .then(data => {
+    // 100 pixels wide, auto-scaled height
+  });
+```
+
+```javascript
+sharp(input)
+  .resize({ height: 100 })
+  .toBuffer()
+  .then(data => {
+    // 100 pixels high, auto-scaled width
+  });
+```
+
+```javascript
+sharp(input)
+  .resize(200, 300, {
+    kernel: sharp.kernel.nearest,
+    fit: 'contain',
+    position: 'right top',
+    background: { r: 255, g: 255, b: 255, alpha: 0.5 }
+  })
+  .toFile('output.png')
+  .then(() => {
+    // output.png is a 200 pixels wide and 300 pixels high image
+    // containing a nearest-neighbour scaled version
+    // contained within the north-east corner of a semi-transparent white canvas
+  });
+```
+
+```javascript
+const transformer = sharp()
+  .resize({
+    width: 200,
+    height: 200,
+    fit: sharp.fit.cover,
+    position: sharp.strategy.entropy
+  });
+// Read image data from readableStream
+// Write 200px square auto-cropped image data to writableStream
+readableStream
+  .pipe(transformer)
+  .pipe(writableStream);
+```
+
+```javascript
+sharp(input)
+  .resize(200, 200, {
+    fit: sharp.fit.inside,
+    withoutEnlargement: true
+  })
+  .toFormat('jpeg')
+  .toBuffer()
+  .then(function(outputBuffer) {
+    // outputBuffer contains JPEG image data
+    // no wider and no higher than 200 pixels
+    // and no larger than the input image
+  });
+```
+
+-   Throws **[Error][12]** Invalid parameters
+
+Returns **Sharp** 
+
+## extend
+
+Extends/pads the edges of the image with the provided background colour.
+This operation will always occur after resizing and extraction, if any.
+
+### Parameters
+
+-   `extend` **([Number][7] \| [Object][8])** single pixel count to add to all edges or an Object with per-edge counts
+    -   `extend.top` **[Number][7]?** 
+    -   `extend.left` **[Number][7]?** 
+    -   `extend.bottom` **[Number][7]?** 
+    -   `extend.right` **[Number][7]?** 
+    -   `extend.background` **([String][9] \| [Object][8])** background colour, parsed by the [color][10] module, defaults to black without transparency. (optional, default `{r:0,g:0,b:0,alpha:1}`)
+
+### Examples
+
+```javascript
+// Resize to 140 pixels wide, then add 10 transparent pixels
+// to the top, left and right edges and 20 to the bottom edge
+sharp(input)
+  .resize(140)
+  .)
+  .extend({
+    top: 10,
+    bottom: 20,
+    left: 10,
+    right: 10
+    background: { r: 0, g: 0, b: 0, alpha: 0 }
+  })
+  ...
+```
+
+-   Throws **[Error][12]** 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][8]** 
+    -   `options.left` **[Number][7]** zero-indexed offset from left edge
+    -   `options.top` **[Number][7]** zero-indexed offset from top edge
+    -   `options.width` **[Number][7]** dimension of extracted image
+    -   `options.height` **[Number][7]** 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][12]** Invalid parameters
+
+Returns **Sharp** 
+
+## trim
+
+Trim "boring" pixels from all edges that contain values similar to the top-left pixel.
+The `info` response Object will contain `trimOffsetLeft` and `trimOffsetTop` properties.
+
+### Parameters
+
+-   `threshold` **[Number][7]** the allowed difference from the top-left pixel, a number greater than zero. (optional, default `10`)
+
+
+-   Throws **[Error][12]** Invalid parameters
+
+Returns **Sharp** 
+
+[1]: https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit
+
+[2]: https://developer.mozilla.org/en-US/docs/Web/CSS/object-position
+
+[3]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29
+
+[4]: http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation
+
+[5]: https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
+
+[6]: https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+
+[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+
+[10]: https://www.npmjs.org/package/color
+
+[11]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
+
+[12]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-utility.md

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

docs/changelog.md

@@ -0,0 +1,843 @@
+# Changelog
+
+### v0.21 - "*teeth*"
+
+Requires libvips v8.7.0.
+
+#### v0.21.0 - 4<sup>th</sup> October 2018
+
+* Deprecate the following resize-related functions:
+    `crop`, `embed`, `ignoreAspectRatio`, `max`, `min` and `withoutEnlargement`.
+  Access to these is now via options passed to the `resize` function.
+  For example:
+    `embed('north')` is now `resize(width, height, { fit: 'contain', position: 'north' })`,
+    `crop('attention')` is now `resize(width, height, { fit: 'cover', position: 'attention' })`,
+    `max().withoutEnlargement()` is now `resize(width, height, { fit: 'inside', withoutEnlargement: true })`.
+  [#1135](https://github.com/lovell/sharp/issues/1135)
+
+* Deprecate the `background` function.
+    Per-operation `background` options added to `resize`, `extend` and `flatten` operations.
+  [#1392](https://github.com/lovell/sharp/issues/1392)
+
+* Add `size` to `metadata` response (Stream and Buffer input only).
+  [#695](https://github.com/lovell/sharp/issues/695)
+
+* Switch from custom trim operation to `vips_find_trim`.
+  [#914](https://github.com/lovell/sharp/issues/914)
+
+* Add `chromaSubsampling` and `isProgressive` properties to `metadata` response.
+  [#1186](https://github.com/lovell/sharp/issues/1186)
+
+* Drop Node 4 support.
+  [#1212](https://github.com/lovell/sharp/issues/1212)
+
+* Enable SIMD convolution by default.
+  [#1213](https://github.com/lovell/sharp/issues/1213)
+
+* Add experimental prebuilt binaries for musl-based Linux.
+  [#1379](https://github.com/lovell/sharp/issues/1379)
+
+* Add support for arbitrary rotation angle via vips_rotate.
+  [#1385](https://github.com/lovell/sharp/pull/1385)
+  [@freezy](https://github.com/freezy)
+
+### v0.20 - "*prebuild*"
+
+Requires libvips v8.6.1.
+
+#### v0.20.8 - 5<sup>th</sup> September 2018
+
+* Avoid race conditions when creating directories during installation.
+  [#1358](https://github.com/lovell/sharp/pull/1358)
+  [@ajhool](https://github.com/ajhool)
+
+* Accept floating point values for input density parameter.
+  [#1362](https://github.com/lovell/sharp/pull/1362)
+  [@aeirola](https://github.com/aeirola)
+
+#### v0.20.7 - 21<sup>st</sup> August 2018
+
+* Use copy+unlink if rename operation fails during installation.
+  [#1345](https://github.com/lovell/sharp/issues/1345)
+
+#### v0.20.6 - 20<sup>th</sup> August 2018
+
+* Add removeAlpha operation to remove alpha channel, if any.
+  [#1248](https://github.com/lovell/sharp/issues/1248)
+
+* Expose mozjpeg quant_table flag.
+  [#1285](https://github.com/lovell/sharp/pull/1285)
+  [@rexxars](https://github.com/rexxars)
+
+* Allow full WebP alphaQuality range of 0-100.
+  [#1290](https://github.com/lovell/sharp/pull/1290)
+  [@sylvaindumont](https://github.com/sylvaindumont)
+
+* Cache libvips binaries to reduce re-install time.
+  [#1301](https://github.com/lovell/sharp/issues/1301)
+
+* Ensure vendor platform mismatch throws error at install time.
+  [#1303](https://github.com/lovell/sharp/issues/1303)
+
+* Improve install time error messages for FreeBSD users.
+  [#1310](https://github.com/lovell/sharp/issues/1310)
+
+* Ensure extractChannel works with 16-bit images.
+  [#1330](https://github.com/lovell/sharp/issues/1330)
+
+* Expose depth option for tile-based output.
+  [#1342](https://github.com/lovell/sharp/pull/1342)
+  [@alundavies](https://github.com/alundavies)
+
+* Add experimental entropy field to stats response.
+
+#### v0.20.5 - 27<sup>th</sup> June 2018
+
+* Expose libjpeg optimize_coding flag.
+  [#1265](https://github.com/lovell/sharp/pull/1265)
+  [@tomlokhorst](https://github.com/tomlokhorst)
+
+#### v0.20.4 - 20<sup>th</sup> June 2018
+
+* Prevent possible rounding error when using shrink-on-load and 90/270 degree rotation.
+  [#1241](https://github.com/lovell/sharp/issues/1241)
+  [@anahit42](https://github.com/anahit42)
+
+* Ensure extractChannel sets correct single-channel colour space interpretation.
+  [#1257](https://github.com/lovell/sharp/issues/1257)
+  [@jeremychone](https://github.com/jeremychone)
+
+#### v0.20.3 - 29<sup>th</sup> May 2018
+
+* Fix tint operation by ensuring LAB interpretation and allowing negative values.
+  [#1235](https://github.com/lovell/sharp/issues/1235)
+  [@wezside](https://github.com/wezside)
+
+#### v0.20.2 - 28<sup>th</sup> April 2018
+
+* Add tint operation to set image chroma.
+  [#825](https://github.com/lovell/sharp/pull/825)
+  [@rikh42](https://github.com/rikh42)
+
+* Add environment variable to ignore globally-installed libvips.
+  [#1165](https://github.com/lovell/sharp/pull/1165)
+  [@oncletom](https://github.com/oncletom)
+
+* Add support for page selection with multi-page input (GIF/TIFF).
+  [#1204](https://github.com/lovell/sharp/pull/1204)
+  [@woolite64](https://github.com/woolite64)
+
+* Add support for Group4 (CCITTFAX4) compression with TIFF output.
+  [#1208](https://github.com/lovell/sharp/pull/1208)
+  [@woolite64](https://github.com/woolite64)
+
+#### v0.20.1 - 17<sup>th</sup> March 2018
+
+* Improve installation experience when a globally-installed libvips below the minimum required version is found.
+  [#1148](https://github.com/lovell/sharp/issues/1148)
+
+* Prevent smartcrop error when cumulative rounding is below target size.
+  [#1154](https://github.com/lovell/sharp/issues/1154)
+  [@ralrom](https://github.com/ralrom)
+
+* Expose libvips' median filter operation.
+  [#1161](https://github.com/lovell/sharp/pull/1161)
+  [@BiancoA](https://github.com/BiancoA)
+
+#### v0.20.0 - 5<sup>th</sup> March 2018
+
+* Add support for prebuilt sharp binaries on common platforms.
+  [#186](https://github.com/lovell/sharp/issues/186)
+
+### v0.19 - "*suit*"
+
+Requires libvips v8.6.1.
+
+#### v0.19.1 - 24<sup>th</sup> February 2018
+
+* Expose libvips' linear transform feature.
+  [#1024](https://github.com/lovell/sharp/pull/1024)
+  [@3epnm](https://github.com/3epnm)
+
+* Expose angle option for tile-based output.
+  [#1121](https://github.com/lovell/sharp/pull/1121)
+  [@BiancoA](https://github.com/BiancoA)
+
+* Prevent crop operation when image already at or below target dimensions.
+  [#1134](https://github.com/lovell/sharp/issues/1134)
+  [@pieh](https://github.com/pieh)
+
+#### v0.19.0 - 11<sup>th</sup> January 2018
+
+* Expose offset coordinates of strategy-based crop.
+  [#868](https://github.com/lovell/sharp/issues/868)
+  [@mirohristov-com](https://github.com/mirohristov-com)
+
+* PNG output now defaults to adaptiveFiltering=false, compressionLevel=9
+  [#872](https://github.com/lovell/sharp/issues/872)
+  [@wmertens](https://github.com/wmertens)
+
+* Add stats feature for pixel-derived image statistics.
+  [#915](https://github.com/lovell/sharp/pull/915)
+  [@rnanwani](https://github.com/rnanwani)
+
+* Add failOnError option to fail-fast on bad input image data.
+  [#976](https://github.com/lovell/sharp/pull/976)
+  [@mceachen](https://github.com/mceachen)
+
+* Resize: switch to libvips' implementation, make fastShrinkOnLoad optional, remove interpolator and centreSampling options.
+  [#977](https://github.com/lovell/sharp/pull/977)
+  [@jardakotesovec](https://github.com/jardakotesovec)
+
+* Attach finish event listener to a clone only for Stream-based input.
+  [#995](https://github.com/lovell/sharp/issues/995)
+  [@whmountains](https://github.com/whmountains)
+
+* Add tilecache before smartcrop to avoid over-computation of previous operations.
+  [#1028](https://github.com/lovell/sharp/issues/1028)
+  [@coffeebite](https://github.com/coffeebite)
+
+* Prevent toFile extension taking precedence over requested format.
+  [#1037](https://github.com/lovell/sharp/issues/1037)
+  [@tomgallagher](https://github.com/tomgallagher)
+
+* Add support for gravity option to existing embed feature.
+  [#1038](https://github.com/lovell/sharp/pull/1038)
+  [@AzureByte](https://github.com/AzureByte)
+
+* Expose IPTC and XMP metadata when available.
+  [#1079](https://github.com/lovell/sharp/pull/1079)
+  [@oaleynik](https://github.com/oaleynik)
+
+* TIFF output: switch default predictor from 'none' to 'horizontal' to match libvips' behaviour.
+
+### v0.18 - "*ridge*"
+
+Requires libvips v8.5.5.
+
+#### v0.18.4 - 18<sup>th</sup> September 2017
+
+* Ensure input Buffer really is marked as Persistent, prevents mark-sweep GC.
+  [#950](https://github.com/lovell/sharp/issues/950)
+  [@lfdoherty](https://github.com/lfdoherty)
+
+#### v0.18.3 - 13<sup>th</sup> September 2017
+
+* Skip shrink-on-load when trimming.
+  [#888](https://github.com/lovell/sharp/pull/888)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Migrate from got to simple-get for basic auth support.
+  [#945](https://github.com/lovell/sharp/pull/945)
+  [@pbomb](https://github.com/pbomb)
+
+#### v0.18.2 - 1<sup>st</sup> July 2017
+
+* Expose libvips' xres and yres properties for TIFF output.
+  [#828](https://github.com/lovell/sharp/pull/828)
+  [@YvesBos](https://github.com/YvesBos)
+
+* Ensure flip and flop operations work with auto-rotate.
+  [#837](https://github.com/lovell/sharp/issues/837)
+  [@rexxars](https://github.com/rexxars)
+
+* Allow binary download URL override via SHARP_DIST_BASE_URL env variable.
+  [#841](https://github.com/lovell/sharp/issues/841)
+
+* Add support for Solus Linux.
+  [#857](https://github.com/lovell/sharp/pull/857)
+  [@ekremkaraca](https://github.com/ekremkaraca)
+
+#### v0.18.1 - 30<sup>th</sup> May 2017
+
+* Remove regression from #781 that could cause incorrect shrink calculation.
+  [#831](https://github.com/lovell/sharp/issues/831)
+  [@suprMax](https://github.com/suprMax)
+
+#### v0.18.0 - 30<sup>th</sup> May 2017
+
+* Remove the previously-deprecated output format "option" functions:
+    quality, progressive, compressionLevel, withoutAdaptiveFiltering,
+    withoutChromaSubsampling, trellisQuantisation, trellisQuantization,
+    overshootDeringing, optimiseScans and optimizeScans.
+
+* Ensure maximum output dimensions are based on the format to be used.
+  [#176](https://github.com/lovell/sharp/issues/176)
+  [@stephanebachelier](https://github.com/stephanebachelier)
+
+* Avoid costly (un)premultiply when using overlayWith without alpha channel.
+  [#573](https://github.com/lovell/sharp/issues/573)
+  [@strarsis](https://github.com/strarsis)
+
+* Include pixel depth (e.g. "uchar") when reading metadata.
+  [#577](https://github.com/lovell/sharp/issues/577)
+  [@moedusa](https://github.com/moedusa)
+
+* Add support for Buffer and Stream-based TIFF output.
+  [#587](https://github.com/lovell/sharp/issues/587)
+  [@strarsis](https://github.com/strarsis)
+
+* Expose warnings from libvips via NODE_DEBUG=sharp environment variable.
+  [#607](https://github.com/lovell/sharp/issues/607)
+  [@puzrin](https://github.com/puzrin)
+
+* Switch to the libvips implementation of "attention" and "entropy" crop strategies.
+  [#727](https://github.com/lovell/sharp/issues/727)
+
+* Improve performance and accuracy of nearest neighbour integral upsampling.
+  [#752](https://github.com/lovell/sharp/issues/752)
+  [@MrIbby](https://github.com/MrIbby)
+
+* Constructor single argument API: allow plain object, reject null/undefined.
+  [#768](https://github.com/lovell/sharp/issues/768)
+  [@kub1x](https://github.com/kub1x)
+
+* Ensure ARM64 pre-built binaries use correct C++11 ABI version.
+  [#772](https://github.com/lovell/sharp/issues/772)
+  [@ajiratech2](https://github.com/ajiratech2)
+
+* Prevent aliasing by using dynamic values for shrink(-on-load).
+  [#781](https://github.com/lovell/sharp/issues/781)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Expose libvips' "squash" parameter to enable 1-bit TIFF output.
+  [#783](https://github.com/lovell/sharp/pull/783)
+  [@YvesBos](https://github.com/YvesBos)
+
+* Add support for rotation using any multiple of +/-90 degrees.
+  [#791](https://github.com/lovell/sharp/pull/791)
+  [@ncoden](https://github.com/ncoden)
+
+* Add "jpg" alias to toFormat as shortened form of "jpeg".
+  [#814](https://github.com/lovell/sharp/pull/814)
+  [@jingsam](https://github.com/jingsam)
+
+### v0.17 - "*quill*"
+
+Requires libvips v8.4.2.
+
+#### v0.17.3 - 1<sup>st</sup> April 2017
+
+* Allow toBuffer to optionally resolve a Promise with both info and data.
+  [#143](https://github.com/lovell/sharp/issues/143)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Create blank image of given width, height, channels and background.
+  [#470](https://github.com/lovell/sharp/issues/470)
+  [@pjarts](https://github.com/pjarts)
+
+* Add support for the "nearest" kernel for image reductions.
+  [#732](https://github.com/lovell/sharp/pull/732)
+  [@alice0meta](https://github.com/alice0meta)
+
+* Add support for TIFF compression and predictor options.
+  [#738](https://github.com/lovell/sharp/pull/738)
+  [@kristojorg](https://github.com/kristojorg)
+
+#### v0.17.2 - 11<sup>th</sup> February 2017
+
+* Ensure Readable side of Stream can start flowing after Writable side has finished.
+  [#671](https://github.com/lovell/sharp/issues/671)
+  [@danhaller](https://github.com/danhaller)
+
+* Expose WebP alpha quality, lossless and near-lossless output options.
+  [#685](https://github.com/lovell/sharp/pull/685)
+  [@rnanwani](https://github.com/rnanwani)
+
+#### v0.17.1 - 15<sup>th</sup> January 2017
+
+* Improve error messages for invalid parameters.
+  [@spikeon](https://github.com/spikeon)
+  [#644](https://github.com/lovell/sharp/pull/644)
+
+* Simplify expression for finding vips-cpp libdir.
+  [#656](https://github.com/lovell/sharp/pull/656)
+
+* Allow HTTPS-over-HTTP proxy when downloading pre-compiled dependencies.
+  [@wangzhiwei1888](https://github.com/wangzhiwei1888)
+  [#679](https://github.com/lovell/sharp/issues/679)
+
+#### v0.17.0 - 11<sup>th</sup> December 2016
+
+* Drop support for versions of Node prior to v4.
+
+* Deprecate the following output format "option" functions:
+    quality, progressive, compressionLevel, withoutAdaptiveFiltering,
+    withoutChromaSubsampling, trellisQuantisation, trellisQuantization,
+    overshootDeringing, optimiseScans and optimizeScans.
+  Access to these is now via output format functions, for example `quality(n)`
+    is now `jpeg({quality: n})` and/or `webp({quality: n})`.
+
+* Autoconvert GIF and SVG input to PNG output if no other format is specified.
+
+* Expose libvips' "centre" resize option to mimic \*magick's +0.5px convention.
+  [#568](https://github.com/lovell/sharp/issues/568)
+
+* Ensure support for embedded base64 PNG and JPEG images within an SVG.
+  [#601](https://github.com/lovell/sharp/issues/601)
+  [@dynamite-ready](https://github.com/dynamite-ready)
+
+* Ensure premultiply operation occurs before box filter shrink.
+  [#605](https://github.com/lovell/sharp/issues/605)
+  [@CmdrShepardsPie](https://github.com/CmdrShepardsPie)
+  [@teroparvinen](https://github.com/teroparvinen)
+
+* Add support for PNG and WebP tile-based output formats (in addition to JPEG).
+  [#622](https://github.com/lovell/sharp/pull/622)
+  [@ppaskaris](https://github.com/ppaskaris)
+
+* Allow use of extend with greyscale input.
+  [#623](https://github.com/lovell/sharp/pull/623)
+  [@ppaskaris](https://github.com/ppaskaris)
+
+* Allow non-RGB input to embed/extend onto background with an alpha channel.
+  [#646](https://github.com/lovell/sharp/issues/646)
+  [@DaGaMs](https://github.com/DaGaMs)
+
+### v0.16 - "*pencil*"
+
+Requires libvips v8.3.3
+
+#### v0.16.2 - 22<sup>nd</sup> October 2016
+
+* Restrict readelf usage to Linux only when detecting global libvips version.
+  [#602](https://github.com/lovell/sharp/issues/602)
+  [@caoko](https://github.com/caoko)
+
+#### v0.16.1 - 13<sup>th</sup> October 2016
+
+* C++11 ABI version is now auto-detected, remove sharp-cxx11 installation flag.
+
+* Add experimental 'attention' crop strategy.
+  [#295](https://github.com/lovell/sharp/issues/295)
+
+* Include .node extension for Meteor's require() implementation.
+  [#537](https://github.com/lovell/sharp/issues/537)
+  [@isjackwild](https://github.com/isjackwild)
+
+* Ensure convolution kernel scale is clamped to a minimum value of 1.
+  [#561](https://github.com/lovell/sharp/issues/561)
+  [@abagshaw](https://github.com/abagshaw)
+
+* Correct calculation of y-axis placement when overlaying image at a fixed point.
+  [#566](https://github.com/lovell/sharp/issues/566)
+  [@Nateowami](https://github.com/Nateowami)
+
+#### v0.16.0 - 18<sup>th</sup> August 2016
+
+* Add pre-compiled libvips for OS X, ARMv7 and ARMv8.
+  [#312](https://github.com/lovell/sharp/issues/312)
+
+* Ensure boolean, bandbool, extractChannel ops occur before sRGB conversion.
+  [#504](https://github.com/lovell/sharp/pull/504)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Recalculate factors after WebP shrink-on-load to avoid round-to-zero errors.
+  [#508](https://github.com/lovell/sharp/issues/508)
+  [@asilvas](https://github.com/asilvas)
+
+* Prevent boolean errors during extract operation.
+  [#511](https://github.com/lovell/sharp/pull/511)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add joinChannel and toColourspace/toColorspace operations.
+  [#513](https://github.com/lovell/sharp/pull/513)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add support for raw pixel data with boolean and withOverlay operations.
+  [#516](https://github.com/lovell/sharp/pull/516)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Prevent bandbool creating a single channel sRGB image.
+  [#519](https://github.com/lovell/sharp/pull/519)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Ensure ICC profiles are removed from PNG output unless withMetadata used.
+  [#521](https://github.com/lovell/sharp/issues/521)
+  [@ChrisPinewood](https://github.com/ChrisPinewood)
+
+* Add alpha channels, if missing, to overlayWith images.
+  [#540](https://github.com/lovell/sharp/pull/540)
+  [@cmtt](https://github.com/cmtt)
+
+* Remove deprecated interpolateWith method - use resize(w, h, { interpolator: ... })
+  [#310](https://github.com/lovell/sharp/issues/310)
+
+### v0.15 - "*outfit*"
+
+Requires libvips v8.3.1
+
+#### v0.15.1 - 12<sup>th</sup> July 2016
+
+* Concat Stream-based input in single operation for ~+3% perf and less GC.
+  [#429](https://github.com/lovell/sharp/issues/429)
+  [@papandreou](https://github.com/papandreou)
+
+* Add alpha channel, if required, before extend operation.
+  [#439](https://github.com/lovell/sharp/pull/439)
+  [@frulo](https://github.com/frulo)
+
+* Allow overlay image to be repeated across entire image via tile option.
+  [#443](https://github.com/lovell/sharp/pull/443)
+  [@lemnisk8](https://github.com/lemnisk8)
+
+* Add cutout option to overlayWith feature, applies only the alpha channel of the overlay image.
+  [#448](https://github.com/lovell/sharp/pull/448)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Ensure scaling factors are calculated independently to prevent rounding errors.
+  [#452](https://github.com/lovell/sharp/issues/452)
+  [@puzrin](https://github.com/puzrin)
+
+* Add --sharp-cxx11 flag to compile with gcc's new C++11 ABI.
+  [#456](https://github.com/lovell/sharp/pull/456)
+  [@kapouer](https://github.com/kapouer)
+
+* Add top/left offset support to overlayWith operation.
+  [#473](https://github.com/lovell/sharp/pull/473)
+  [@rnanwani](https://github.com/rnanwani)
+
+* Add convolve operation for kernel-based convolution.
+  [#479](https://github.com/lovell/sharp/pull/479)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add greyscale option to threshold operation for colourspace conversion control.
+  [#480](https://github.com/lovell/sharp/pull/480)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Ensure ICC profiles are licenced for distribution.
+  [#486](https://github.com/lovell/sharp/issues/486)
+  [@kapouer](https://github.com/kapouer)
+
+* Allow images with an alpha channel to work with LAB-colourspace based sharpen.
+  [#490](https://github.com/lovell/sharp/issues/490)
+  [@jwagner](https://github.com/jwagner)
+
+* Add trim operation to remove "boring" edges.
+  [#492](https://github.com/lovell/sharp/pull/492)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Add bandbool feature for channel-wise boolean operations.
+  [#496](https://github.com/lovell/sharp/pull/496)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add extractChannel operation to extract a channel from an image.
+  [#497](https://github.com/lovell/sharp/pull/497)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add ability to read and write native libvips .v files.
+  [#500](https://github.com/lovell/sharp/pull/500)
+  [@mhirsch](https://github.com/mhirsch)
+
+* Add boolean feature for bitwise image operations.
+  [#501](https://github.com/lovell/sharp/pull/501)
+  [@mhirsch](https://github.com/mhirsch)
+
+#### v0.15.0 - 21<sup>st</sup> May 2016
+
+* Use libvips' new Lanczos 3 kernel as default for image reduction.
+  Deprecate interpolateWith method, now provided as a resize option.
+  [#310](https://github.com/lovell/sharp/issues/310)
+  [@jcupitt](https://github.com/jcupitt)
+
+* Take advantage of libvips v8.3 features.
+  Add support for libvips' new GIF and SVG loaders.
+  Pre-built binaries now include giflib and librsvg, exclude *magick.
+  Use shrink-on-load for WebP input.
+  Break existing sharpen API to accept sigma and improve precision.
+  [#369](https://github.com/lovell/sharp/issues/369)
+
+* Remove unnecessary (un)premultiply operations when not resizing/compositing.
+  [#413](https://github.com/lovell/sharp/issues/413)
+  [@jardakotesovec](https://github.com/jardakotesovec)
+
+### v0.14 - "*needle*"
+
+Requires libvips v8.2.3
+
+#### v0.14.1 - 16<sup>th</sup> April 2016
+
+* Allow removal of limitation on input pixel count via limitInputPixels. Use with care.
+  [#250](https://github.com/lovell/sharp/issues/250)
+  [#316](https://github.com/lovell/sharp/pull/316)
+  [@anandthakker](https://github.com/anandthakker)
+  [@kentongray](https://github.com/kentongray)
+
+* Use final output image for metadata passed to callback.
+  [#399](https://github.com/lovell/sharp/pull/399)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Add support for writing tiled images to a zip container.
+  [#402](https://github.com/lovell/sharp/pull/402)
+  [@felixbuenemann](https://github.com/felixbuenemann)
+
+* Allow use of embed with 1 and 2 channel images.
+  [#411](https://github.com/lovell/sharp/issues/411)
+  [@janaz](https://github.com/janaz)
+
+* Improve Electron compatibility by allowing node-gyp rebuilds without npm.
+  [#412](https://github.com/lovell/sharp/issues/412)
+  [@nouh](https://github.com/nouh)
+
+#### v0.14.0 - 2<sup>nd</sup> April 2016
+
+* Add ability to extend (pad) the edges of an image.
+  [#128](https://github.com/lovell/sharp/issues/128)
+  [@blowsie](https://github.com/blowsie)
+
+* Add support for Zoomify and Google tile layouts. Breaks existing tile API.
+  [#223](https://github.com/lovell/sharp/issues/223)
+  [@bdunnette](https://github.com/bdunnette)
+
+* Improvements to overlayWith: differing sizes/formats, gravity, buffer input.
+  [#239](https://github.com/lovell/sharp/issues/239)
+  [@chrisriley](https://github.com/chrisriley)
+
+* Add entropy-based crop strategy to remove least interesting edges.
+  [#295](https://github.com/lovell/sharp/issues/295)
+  [@rightaway](https://github.com/rightaway)
+
+* Expose density metadata; set density of images from vector input.
+  [#338](https://github.com/lovell/sharp/issues/338)
+  [@lookfirst](https://github.com/lookfirst)
+
+* Emit post-processing 'info' event for Stream output.
+  [#367](https://github.com/lovell/sharp/issues/367)
+  [@salzhrani](https://github.com/salzhrani)
+
+* Ensure output image EXIF Orientation values are within 1-8 range.
+  [#385](https://github.com/lovell/sharp/pull/385)
+  [@jtobinisaniceguy](https://github.com/jtobinisaniceguy)
+
+* Ensure ratios are not swapped when rotating 90/270 and ignoring aspect.
+  [#387](https://github.com/lovell/sharp/issues/387)
+  [@kleisauke](https://github.com/kleisauke)
+
+* Remove deprecated style of calling extract API. Breaks calls using positional arguments.
+  [#276](https://github.com/lovell/sharp/issues/276)
+
+### v0.13 - "*mind*"
+
+Requires libvips v8.2.2
+
+#### v0.13.1 - 27<sup>th</sup> February 2016
+
+* Fix embedding onto transparent backgrounds; regression introduced in v0.13.0.
+  [#366](https://github.com/lovell/sharp/issues/366)
+  [@diegocsandrim](https://github.com/diegocsandrim)
+
+#### v0.13.0 - 15<sup>th</sup> February 2016
+
+* Improve vector image support by allowing control of density/DPI.
+  Switch pre-built libs from Imagemagick to Graphicsmagick.
+  [#110](https://github.com/lovell/sharp/issues/110)
+  [@bradisbell](https://github.com/bradisbell)
+
+* Add support for raw, uncompressed pixel Buffer/Stream input.
+  [#220](https://github.com/lovell/sharp/issues/220)
+  [@mikemorris](https://github.com/mikemorris)
+
+* Switch from libvips' C to C++ bindings, requires upgrade to v8.2.2.
+  [#299](https://github.com/lovell/sharp/issues/299)
+
+* Control number of open files in libvips' cache; breaks existing `cache` behaviour.
+  [#315](https://github.com/lovell/sharp/issues/315)
+  [@impomezia](https://github.com/impomezia)
+
+* Ensure 16-bit input images can be normalised and embedded onto transparent backgrounds.
+  [#339](https://github.com/lovell/sharp/issues/339)
+  [#340](https://github.com/lovell/sharp/issues/340)
+  [@janaz](https://github.com/janaz)
+
+* Ensure selected format takes precedence over any unknown output filename extension.
+  [#344](https://github.com/lovell/sharp/issues/344)
+  [@ubaltaci](https://github.com/ubaltaci)
+
+* Add support for libvips' PBM, PGM, PPM and FITS image format loaders.
+  [#347](https://github.com/lovell/sharp/issues/347)
+  [@oaleynik](https://github.com/oaleynik)
+
+* Ensure default crop gravity is center/centre.
+  [#351](https://github.com/lovell/sharp/pull/351)
+  [@joelmukuthu](https://github.com/joelmukuthu)
+
+* Improve support for musl libc systems e.g. Alpine Linux.
+  [#354](https://github.com/lovell/sharp/issues/354)
+  [#359](https://github.com/lovell/sharp/pull/359)
+  [@download13](https://github.com/download13)
+  [@wjordan](https://github.com/wjordan)
+
+* Small optimisation when reducing by an integral factor to favour shrink over affine.
+
+* Add support for gamma correction of images with an alpha channel.
+
+### v0.12 - "*look*"
+
+Requires libvips v8.2.0
+
+#### v0.12.2 - 16<sup>th</sup> January 2016
+
+* Upgrade libvips to v8.2.0 for improved vips_shrink.
+
+* Add pre-compiled libvips for ARMv6+ CPUs.
+
+* Ensure 16-bit input images work with embed option.
+  [#325](https://github.com/lovell/sharp/issues/325)
+  [@janaz](https://github.com/janaz)
+
+* Allow compilation with gmake to provide FreeBSD support.
+  [#326](https://github.com/lovell/sharp/issues/326)
+  [@c0decafe](https://github.com/c0decafe)
+
+* Attempt to remove temporary file after installation.
+  [#331](https://github.com/lovell/sharp/issues/331)
+  [@dtoubelis](https://github.com/dtoubelis)
+
+#### v0.12.1 - 12<sup>th</sup> December 2015
+
+* Allow use of SIMD vector instructions (via liborc) to be toggled on/off.
+  [#172](https://github.com/lovell/sharp/issues/172)
+  [@bkw](https://github.com/bkw)
+  [@puzrin](https://github.com/puzrin)
+
+* Ensure embedded ICC profiles output with perceptual intent.
+  [#321](https://github.com/lovell/sharp/issues/321)
+  [@vlapo](https://github.com/vlapo)
+
+* Use the NPM-configured HTTPS proxy, if any, for binary downloads.
+
+#### v0.12.0 - 23<sup>rd</sup> November 2015
+
+* Bundle pre-compiled libvips and its dependencies for 64-bit Linux and Windows.
+  [#42](https://github.com/lovell/sharp/issues/42)
+
+* Take advantage of libvips v8.1.0+ features.
+  [#152](https://github.com/lovell/sharp/issues/152)
+
+* Add support for 64-bit Windows. Drop support for 32-bit Windows.
+  [#224](https://github.com/lovell/sharp/issues/224)
+  [@sabrehagen](https://github.com/sabrehagen)
+
+* Switch default interpolator to bicubic.
+  [#289](https://github.com/lovell/sharp/issues/289)
+  [@mahnunchik](https://github.com/mahnunchik)
+
+* Pre-extract rotatation should not swap width/height.
+  [#296](https://github.com/lovell/sharp/issues/296)
+  [@asilvas](https://github.com/asilvas)
+
+* Ensure 16-bit+alpha input images are (un)premultiplied correctly.
+  [#301](https://github.com/lovell/sharp/issues/301)
+  [@izaakschroeder](https://github.com/izaakschroeder)
+
+* Add `threshold` operation.
+  [#303](https://github.com/lovell/sharp/pull/303)
+  [@dacarley](https://github.com/dacarley)
+
+* Add `negate` operation.
+  [#306](https://github.com/lovell/sharp/pull/306)
+  [@dacarley](https://github.com/dacarley)
+
+* Support `options` Object with existing `extract` operation.
+  [#309](https://github.com/lovell/sharp/pull/309)
+  [@papandreou](https://github.com/papandreou)
+
+### v0.11 - "*knife*"
+
+#### v0.11.4 - 5<sup>th</sup> November 2015
+
+* Add corners, e.g. `northeast`, to existing `gravity` option.
+  [#291](https://github.com/lovell/sharp/pull/291)
+  [@brandonaaron](https://github.com/brandonaaron)
+
+* Ensure correct auto-rotation for EXIF Orientation values 2 and 4.
+  [#288](https://github.com/lovell/sharp/pull/288)
+  [@brandonaaron](https://github.com/brandonaaron)
+
+* Make static linking possible via `--runtime_link` install option.
+  [#287](https://github.com/lovell/sharp/pull/287)
+  [@vlapo](https://github.com/vlapo)
+
+#### v0.11.3 - 8<sup>th</sup> September 2015
+
+* Intrepret blurSigma, sharpenFlat, and sharpenJagged as double precision.
+  [#263](https://github.com/lovell/sharp/pull/263)
+  [@chrisriley](https://github.com/chrisriley)
+
+#### v0.11.2 - 28<sup>th</sup> August 2015
+
+* Allow crop gravity to be provided as a String.
+  [#255](https://github.com/lovell/sharp/pull/255)
+  [@papandreou](https://github.com/papandreou)
+* Add support for io.js v3 and Node v4.
+  [#246](https://github.com/lovell/sharp/issues/246)
+
+#### v0.11.1 - 12<sup>th</sup> August 2015
+
+* Silence MSVC warning: "C4530: C++ exception handler used, but unwind semantics are not enabled".
+  [#244](https://github.com/lovell/sharp/pull/244)
+  [@TheThing](https://github.com/TheThing)
+
+* Suppress gamma correction for input image with alpha transparency.
+  [#249](https://github.com/lovell/sharp/issues/249)
+  [@compeak](https://github.com/compeak)
+
+#### v0.11.0 - 15<sup>th</sup> July 2015
+
+* Allow alpha transparency compositing via new `overlayWith` method.
+  [#97](https://github.com/lovell/sharp/issues/97)
+  [@gasi](https://github.com/gasi)
+
+* Expose raw ICC profile data as a Buffer when using `metadata`.
+  [#129](https://github.com/lovell/sharp/issues/129)
+  [@homerjam](https://github.com/homerjam)
+
+* Allow image header updates via a parameter passed to existing `withMetadata` method.
+  Provide initial support for EXIF `Orientation` tag,
+  which if present is now removed when using `rotate`, `flip` or `flop`.
+  [#189](https://github.com/lovell/sharp/issues/189)
+  [@h2non](https://github.com/h2non)
+
+* Tighten constructor parameter checks.
+  [#221](https://github.com/lovell/sharp/issues/221)
+  [@mikemorris](https://github.com/mikemorris)
+
+* Allow one input Stream to be shared with two or more output Streams via new `clone` method.
+  [#235](https://github.com/lovell/sharp/issues/235)
+  [@jaubourg](https://github.com/jaubourg)
+
+* Use `round` instead of `floor` when auto-scaling dimensions to avoid floating-point rounding errors.
+  [#238](https://github.com/lovell/sharp/issues/238)
+  [@richardadjogah](https://github.com/richardadjogah)
+
+### v0.10 - "*judgment*"
+
+#### v0.10.1 - 1<sup>st</sup> June 2015
+
+* Allow embed of image with alpha transparency onto non-transparent background.
+  [#204](https://github.com/lovell/sharp/issues/204)
+  [@mikemliu](https://github.com/mikemliu)
+
+* Include C standard library for `atoi` as Xcode 6.3 appears to no longer do this.
+  [#228](https://github.com/lovell/sharp/issues/228)
+  [@doggan](https://github.com/doggan)
+
+#### v0.10.0 - 23<sup>rd</sup> April 2015
+
+* Add support for Windows (x86).
+  [#19](https://github.com/lovell/sharp/issues/19)
+  [@DullReferenceException](https://github.com/DullReferenceException)
+  [@itsananderson](https://github.com/itsananderson)
+
+* Add support for Openslide input and DeepZoom output.
+  [#146](https://github.com/lovell/sharp/issues/146)
+  [@mvictoras](https://github.com/mvictoras)
+
+* Allow arbitrary aspect ratios when resizing images via new `ignoreAspectRatio` method.
+  [#192](https://github.com/lovell/sharp/issues/192)
+  [@skedastik](https://github.com/skedastik)
+
+* Enhance output image contrast by stretching its luminance to cover the full dynamic range via new `normalize` method.
+  [#194](https://github.com/lovell/sharp/issues/194)
+  [@bkw](https://github.com/bkw)
+  [@codingforce](https://github.com/codingforce)

docs/css/extra.css

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

docs/index.md

@@ -0,0 +1,138 @@
+# 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.
+
+Most modern 64-bit OS X, Windows and Linux systems running
+Node versions 6, 8 and 10
+do not require any additional install or runtime dependencies.
+
+[![Test Coverage](https://coveralls.io/repos/lovell/sharp/badge.png?branch=master)](https://coveralls.io/r/lovell/sharp?branch=master)
+
+### Formats
+
+This module supports reading JPEG, PNG, WebP, TIFF, GIF and SVG images.
+
+Output images can be in JPEG, PNG, WebP and TIFF formats as well as uncompressed raw pixel data.
+
+Streams, Buffer objects and the filesystem can be used for input and output.
+
+A single input Stream can be split into multiple processing pipelines and output Streams.
+
+Deep Zoom image pyramids can be generated,
+suitable for use with "slippy map" tile viewers like
+[OpenSeadragon](https://github.com/openseadragon/openseadragon)
+and [Leaflet](https://github.com/turban/Leaflet.Zoomify).
+
+### Fast
+
+This module is powered by the blazingly fast
+[libvips](https://github.com/libvips/libvips) image processing library,
+originally created in 1989 at Birkbeck College
+and currently maintained by
+[John Cupitt](https://github.com/jcupitt).
+
+Only small regions of uncompressed image data
+are held in memory and processed at a time,
+taking full advantage of multiple CPU cores and L1/L2/L3 cache.
+
+Everything remains non-blocking thanks to _libuv_,
+no child processes are spawned and Promises/async/await are supported.
+
+### Optimal
+
+Huffman tables are optimised when generating JPEG output images
+without having to use separate command line tools like
+[jpegoptim](https://github.com/tjko/jpegoptim) and
+[jpegtran](http://jpegclub.org/jpegtran/).
+
+PNG filtering is disabled by default,
+which for diagrams and line art often produces the same result
+as [pngcrush](https://pmt.sourceforge.io/pngcrush/).
+
+### Contributing
+
+A [guide for contributors](https://github.com/lovell/sharp/blob/master/CONTRIBUTING.md)
+covers reporting bugs, requesting features and submitting code changes.
+
+### Credits
+
+This module would never have been possible without
+the help and code contributions of the following people:
+
+* [John Cupitt](https://github.com/jcupitt)
+* [Pierre Inglebert](https://github.com/pierreinglebert)
+* [Jonathan Ong](https://github.com/jonathanong)
+* [Chanon Sajjamanochai](https://github.com/chanon)
+* [Juliano Julio](https://github.com/julianojulio)
+* [Daniel Gasienica](https://github.com/gasi)
+* [Julian Walker](https://github.com/julianwa)
+* [Amit Pitaru](https://github.com/apitaru)
+* [Brandon Aaron](https://github.com/brandonaaron)
+* [Andreas Lind](https://github.com/papandreou)
+* [Maurus Cuelenaere](https://github.com/mcuelenaere)
+* [Linus Unnebäck](https://github.com/LinusU)
+* [Victor Mateevitsi](https://github.com/mvictoras)
+* [Alaric Holloway](https://github.com/skedastik)
+* [Bernhard K. Weisshuhn](https://github.com/bkw)
+* [David A. Carley](https://github.com/dacarley)
+* [John Tobin](https://github.com/jtobinisaniceguy)
+* [Kenton Gray](https://github.com/kentongray)
+* [Felix Bünemann](https://github.com/felixbuenemann)
+* [Samy Al Zahrani](https://github.com/salzhrani)
+* [Chintan Thakkar](https://github.com/lemnisk8)
+* [F. Orlando Galashan](https://github.com/frulo)
+* [Kleis Auke Wolthuizen](https://github.com/kleisauke)
+* [Matt Hirsch](https://github.com/mhirsch)
+* [Rahul Nanwani](https://github.com/rnanwani)
+* [Matthias Thoemmes](https://github.com/cmtt)
+* [Patrick Paskaris](https://github.com/ppaskaris)
+* [Jérémy Lal](https://github.com/kapouer)
+* [Alice Monday](https://github.com/alice0meta)
+* [Kristo Jorgenson](https://github.com/kristojorg)
+* [Yves Bos](https://github.com/YvesBos)
+* [Nicolas Coden](https://github.com/ncoden)
+* [Matt Parrish](https://github.com/pbomb)
+* [Matthew McEachen](https://github.com/mceachen)
+* [Jarda Kotěšovec](https://github.com/jardakotesovec)
+* [Kenric D'Souza](https://github.com/AzureByte)
+* [Oleh Aleinyk](https://github.com/oaleynik)
+* [Marcel Bretschneider](https://github.com/3epnm)
+* [Andrea Bianco](https://github.com/BiancoA)
+* [Rik Heywood](https://github.com/rikh42)
+* [Thomas Parisot](https://github.com/oncletom)
+* [Nathan Graves](https://github.com/woolite64)
+* [Tom Lokhorst](https://github.com/tomlokhorst)
+* [Espen Hovlandsdal](https://github.com/rexxars)
+* [Sylvain Dumont](https://github.com/sylvaindumont)
+* [Alun Davies](https://github.com/alundavies)
+* [Aidan Hoolachan](https://github.com/ajhool)
+* [Axel Eirola](https://github.com/aeirola)
+* [Freezy](https://github.com/freezy)
+
+Thank you!
+
+### Licensing
+
+Copyright 2013, 2014, 2015, 2016, 2017, 2018 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 +1,265 @@
+# Installation
+
+```sh
+npm install sharp
+```
+
+```sh
+yarn add sharp
+```
+
+## Prerequisites
+
+* Node v4.5.0+
+
+### Building from source
+
+Pre-compiled binaries for sharp are provided for use with
+Node versions 6, 8 and 10 on
+64-bit Windows, OS X and Linux platforms.
+
+Sharp will be built from source at install time when:
+
+* a globally-installed libvips is detected,
+* pre-compiled binaries do not exist for the current platform and Node version, or
+* when the `npm install --build-from-source` flag is used.
+
+Building from source requires:
+
+* C++11 compatible compiler such as gcc 4.8+, clang 3.0+ or MSVC 2013+
+* [node-gyp](https://github.com/nodejs/node-gyp#installation) and its dependencies (includes Python 2.7)
+
+## libvips
+
+### Linux
+
+[![Ubuntu 16.04 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+
+libvips and its dependencies are fetched and stored within `node_modules/sharp/vendor` during `npm install`.
+This involves an automated HTTPS download of approximately 8MB.
+
+Most Linux-based (glibc, musl) operating systems running on x64 and ARMv6+ CPUs should "just work", e.g.:
+
+* Debian 7+
+* Ubuntu 14.04+
+* Centos 7+
+* Alpine 3.8+ (Node 8 and 10)
+* Fedora
+* openSUSE 13.2+
+* Archlinux
+* Raspbian Jessie
+* Amazon Linux
+* Solus
+
+To use a globally-installed version of libvips instead of the provided binaries,
+make sure it is at least the version listed under `config.libvips` in the `package.json` file
+and that it can be located using `pkg-config --modversion vips-cpp`.
+
+If you are using non-standard paths (anything other than `/usr` or `/usr/local`),
+you might need to set `PKG_CONFIG_PATH` during `npm install`
+and `LD_LIBRARY_PATH` at runtime.
+
+This allows the use of newer versions of libvips with older versions of sharp.
+
+For 32-bit Intel CPUs and older Linux-based operating systems such as Centos 6,
+compiling libvips from source is recommended.
+
+[https://libvips.github.io/libvips/install.html#building-libvips-from-a-source-tarball](https://libvips.github.io/libvips/install.html#building-libvips-from-a-source-tarball)
+
+#### Alpine Linux
+
+libvips is available in the
+[testing repository](https://pkgs.alpinelinux.org/packages?name=vips-dev):
+
+```sh
+apk add vips-dev fftw-dev build-base --update-cache --repository https://dl-3.alpinelinux.org/alpine/edge/testing/
+```
+
+The smaller stack size of musl libc means
+libvips may need to be used without a cache
+via `sharp.cache(false)` to avoid a stack overflow.
+
+### Mac OS
+
+[![OS X 10.12 Build Status](https://travis-ci.org/lovell/sharp.png?branch=master)](https://travis-ci.org/lovell/sharp)
+
+libvips and its dependencies are fetched and stored within `node_modules/sharp/vendor` during `npm install`.
+This involves an automated HTTPS download of approximately 7MB.
+
+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 13MB.
+
+Only 64-bit (x64) `node.exe` is supported.
+
+### FreeBSD
+
+libvips must be installed before `npm install` is run.
+
+This can be achieved via package or ports:
+
+```sh
+pkg install -y pkgconf vips
+```
+
+```sh
+cd /usr/ports/graphics/vips/ && make install clean
+```
+
+FreeBSD's gcc v4 and v5 need `CXXFLAGS=-D_GLIBCXX_USE_C99` set for C++11 support due to
+https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193528
+
+### Heroku
+
+Set [NODE_MODULES_CACHE](https://devcenter.heroku.com/articles/nodejs-support#cache-behavior)
+to `false` when using the `yarn` package manager.
+
+### Docker
+
+[Marc Bachmann](https://github.com/marcbachmann) maintains an
+[Ubuntu-based Dockerfile for libvips](https://github.com/marcbachmann/dockerfile-libvips).
+
+```sh
+docker pull marcbachmann/libvips
+```
+
+[Will Jordan](https://github.com/wjordan) maintains an
+[Alpine-based Dockerfile for libvips](https://github.com/wjordan/dockerfile-libvips).
+
+```sh
+docker pull wjordan/libvips
+```
+
+[Tailor Brands](https://github.com/TailorBrands) maintain
+[Debian-based Dockerfiles for libvips and nodejs](https://github.com/TailorBrands/docker-libvips).
+
+```sh
+docker pull tailor/docker-libvips
+```
+
+### AWS Lambda
+
+A [deployment package](http://docs.aws.amazon.com/lambda/latest/dg/nodejs-create-deployment-pkg.html) for the
+[Lambda Execution Environment](http://docs.aws.amazon.com/lambda/latest/dg/current-supported-versions.html)
+can be built using Docker.
+
+```sh
+rm -rf node_modules/sharp
+docker run -v "$PWD":/var/task lambci/lambda:build-nodejs8.10 npm install
+```
+
+Set the Lambda runtime to Node.js 8.10.
+
+To get the best performance select the largest memory available.
+A 1536 MB function provides ~12x more CPU time than a 128 MB function.
+
+### NW.js
+
+Run the `nw-gyp` tool after installation.
+
+```sh
+cd node-modules/sharp
+nw-gyp rebuild --arch=x64 --target=[your nw version]
+node node_modules/sharp/install/dll-copy
+```
+
+[http://docs.nwjs.io/en/latest/For%20Users/Advanced/Use%20Native%20Node%20Modules/](http://docs.nwjs.io/en/latest/For%20Users/Advanced/Use%20Native%20Node%20Modules/)
+
+### Build tools
+
+* [gulp-responsive](https://www.npmjs.com/package/gulp-responsive)
+* [grunt-sharp](https://www.npmjs.com/package/grunt-sharp)
+
+### Coding tools
+
+* [Sharp TypeScript Types](https://www.npmjs.com/package/@types/sharp)
+
+### CLI tools
+
+* [sharp-cli](https://www.npmjs.com/package/sharp-cli)
+
+### Security
+
+Many users of this module process untrusted, user-supplied images,
+but there are aspects of security to consider when doing so.
+
+It is possible to compile libvips with support for various third-party image loaders.
+Each of these libraries has undergone differing levels of security testing.
+
+Whilst tools such as [American Fuzzy Lop](http://lcamtuf.coredump.cx/afl/)
+and [Valgrind](http://valgrind.org/) have been used to test
+the most popular web-based formats, as well as libvips itself,
+you are advised to perform your own testing and sandboxing.
+
+### Pre-compiled libvips binaries
+
+This module will attempt to download a pre-compiled bundle of libvips
+and its dependencies on Linux and Windows machines under either of these
+conditions:
+
+1. If a global installation of libvips that meets the
+minimum version requirement cannot be found;
+1. If `SHARP_IGNORE_GLOBAL_LIBVIPS` environment variable is set.
+
+```sh
+SHARP_IGNORE_GLOBAL_LIBVIPS=1 npm install sharp
+```
+
+Should you need to manually download and inspect these files,
+you can do so via
+[https://github.com/lovell/sharp-libvips/releases](https://github.com/lovell/sharp-libvips/releases)
+
+Should you wish to install these from your own location,
+set the `SHARP_DIST_BASE_URL` environment variable, e.g.
+
+```sh
+SHARP_DIST_BASE_URL="https://hostname/path/" npm install sharp
+```
+
+to use `https://hostname/path/libvips-x.y.z-platform.tar.gz`.
+
+### Licences
+
+This module is licensed under the terms of the
+[Apache 2.0 Licence](https://github.com/lovell/sharp/blob/master/LICENSE).
+
+The libraries downloaded and used by this module
+are done so under the terms of the following licences,
+all of which are compatible with the Apache 2.0 Licence.
+
+Use of libraries under the terms of the LGPLv3 is via the
+"any later version" clause of the LGPLv2 or LGPLv2.1.
+
+| Library       | Used under the terms of                                                                                  |
+|---------------|----------------------------------------------------------------------------------------------------------|
+| cairo         | Mozilla Public License 2.0                                                                               |
+| expat         | MIT Licence                                                                                              |
+| fontconfig    | [fontconfig Licence](https://cgit.freedesktop.org/fontconfig/tree/COPYING) (BSD-like)                    |
+| freetype      | [freetype Licence](http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/docs/FTL.TXT) (BSD-like) |
+| fribidi       | LGPLv3                                                                                                   |
+| gettext       | LGPLv3                                                                                                   |
+| giflib        | MIT Licence                                                                                              |
+| glib          | LGPLv3                                                                                                   |
+| harfbuzz      | MIT Licence                                                                                              |
+| lcms          | MIT Licence                                                                                              |
+| libcroco      | LGPLv3                                                                                                   |
+| libexif       | LGPLv3                                                                                                   |
+| libffi        | MIT Licence                                                                                              |
+| libgsf        | LGPLv3                                                                                                   |
+| libjpeg-turbo | [zlib License, IJG License](https://github.com/libjpeg-turbo/libjpeg-turbo/blob/master/LICENSE.md)       |
+| libpng        | [libpng License](http://www.libpng.org/pub/png/src/libpng-LICENSE.txt)                                   |
+| librsvg       | LGPLv3                                                                                                   |
+| libtiff       | [libtiff License](http://www.libtiff.org/misc.html) (BSD-like)                                           |
+| libvips       | LGPLv3                                                                                                   |
+| libwebp       | New BSD License                                                                                          |
+| libxml2       | MIT Licence                                                                                              |
+| pango         | LGPLv3                                                                                                   |
+| pixman        | MIT Licence                                                                                              |
+| zlib          | [zlib Licence](https://github.com/madler/zlib/blob/master/zlib.h)                                        |

docs/performance.md

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

index.js

@@ -1,13 +0,0 @@
-var sharp = require("./build/Release/sharp");
-
-module.exports.crop = function(input, output, width, height, callback) {
-  sharp.resize(input, output, width, height, "c", callback)
-}
-
-module.exports.embedWhite = function(input, output, width, height, callback) {
-  sharp.resize(input, output, width, height, "w", callback)
-}
-
-module.exports.embedBlack = function(input, output, width, height, callback) {
-  sharp.resize(input, output, width, height, "b", callback)
-}

install/dll-copy.js

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

install/libvips.js

@@ -0,0 +1,101 @@
+'use strict';
+
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+const detectLibc = require('detect-libc');
+const npmLog = require('npmlog');
+const semver = require('semver');
+const simpleGet = require('simple-get');
+const tar = require('tar');
+const copyFileSync = require('fs-copy-file-sync');
+
+const agent = require('../lib/agent');
+const libvips = require('../lib/libvips');
+const platform = require('../lib/platform');
+
+const minimumLibvipsVersion = libvips.minimumLibvipsVersion;
+const distBaseUrl = process.env.SHARP_DIST_BASE_URL || `https://github.com/lovell/sharp-libvips/releases/download/v${minimumLibvipsVersion}/`;
+
+const fail = function (err) {
+  npmLog.error('sharp', err.message);
+  npmLog.error('sharp', 'Please see http://sharp.pixelplumbing.com/page/install');
+  process.exit(1);
+};
+
+const extractTarball = function (tarPath) {
+  const vendorPath = path.join(__dirname, '..', 'vendor');
+  libvips.mkdirSync(vendorPath);
+  tar
+    .extract({
+      file: tarPath,
+      cwd: vendorPath,
+      strict: true
+    })
+    .catch(fail);
+};
+
+try {
+  const useGlobalLibvips = libvips.useGlobalLibvips();
+  if (useGlobalLibvips) {
+    const globalLibvipsVersion = libvips.globalLibvipsVersion();
+    npmLog.info('sharp', `Detected globally-installed libvips v${globalLibvipsVersion}`);
+    npmLog.info('sharp', 'Building from source via node-gyp');
+    process.exit(1);
+  } else if (libvips.hasVendoredLibvips()) {
+    npmLog.info('sharp', `Using existing vendored libvips v${minimumLibvipsVersion}`);
+  } else {
+    // Is this arch/platform supported?
+    const arch = process.env.npm_config_arch || process.arch;
+    const platformAndArch = platform();
+    if (platformAndArch === 'win32-ia32') {
+      throw new Error('Windows x86 (32-bit) node.exe is not supported');
+    }
+    if (arch === 'ia32') {
+      throw new Error(`Intel Architecture 32-bit systems require manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    if (platformAndArch === 'freebsd-x64') {
+      throw new Error(`FreeBSD systems require manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    if (detectLibc.family === detectLibc.GLIBC && detectLibc.version && semver.lt(`${detectLibc.version}.0`, '2.13.0')) {
+      throw new Error(`Use with glibc version ${detectLibc.version} requires manual installation of libvips >= ${minimumLibvipsVersion}`);
+    }
+    // Download to per-process temporary file
+    const tarFilename = ['libvips', minimumLibvipsVersion, platformAndArch].join('-') + '.tar.gz';
+    const tarPathCache = path.join(libvips.cachePath(), tarFilename);
+    if (fs.existsSync(tarPathCache)) {
+      npmLog.info('sharp', `Using cached ${tarPathCache}`);
+      extractTarball(tarPathCache);
+    } else {
+      const tarPathTemp = path.join(os.tmpdir(), `${process.pid}-${tarFilename}`);
+      const tmpFile = fs.createWriteStream(tarPathTemp);
+      const url = distBaseUrl + tarFilename;
+      npmLog.info('sharp', `Downloading ${url}`);
+      simpleGet({ url: url, agent: agent() }, function (err, response) {
+        if (err) {
+          throw err;
+        }
+        if (response.statusCode !== 200) {
+          throw new Error(`Status ${response.statusCode}`);
+        }
+        response.pipe(tmpFile);
+      });
+      tmpFile
+        .on('error', fail)
+        .on('close', function () {
+          try {
+            // Attempt to rename
+            fs.renameSync(tarPathTemp, tarPathCache);
+          } catch (err) {
+            // Fall back to copy and unlink
+            copyFileSync(tarPathTemp, tarPathCache);
+            fs.unlinkSync(tarPathTemp);
+          }
+          extractTarball(tarPathCache);
+        });
+    }
+  }
+} catch (err) {
+  fail(err);
+}

lib/agent.js

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

lib/channel.js

@@ -0,0 +1,131 @@
+'use strict';
+
+const is = require('./is');
+
+/**
+ * Boolean operations for bandbool.
+ * @private
+ */
+const bool = {
+  and: 'and',
+  or: 'or',
+  eor: 'eor'
+};
+
+/**
+ * Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
+ *
+ * @example
+ * sharp('rgba.png')
+ *   .removeAlpha()
+ *   .toFile('rgb.png', function(err, info) {
+ *     // rgb.png is a 3 channel image without an alpha channel
+ *   });
+ *
+ * @returns {Sharp}
+ */
+function removeAlpha () {
+  this.options.removeAlpha = true;
+  return this;
+}
+
+/**
+ * Extract a single channel from a multi-channel image.
+ *
+ * @example
+ * sharp(input)
+ *   .extractChannel('green')
+ *   .toFile('input_green.jpg', function(err, info) {
+ *     // info.channels === 1
+ *     // input_green.jpg contains the green channel of the input image
+ *    });
+ *
+ * @param {Number|String} channel - zero-indexed band number to extract, or `red`, `green` or `blue` as alternative to `0`, `1` or `2` respectively.
+ * @returns {Sharp}
+ * @throws {Error} Invalid channel
+ */
+function extractChannel (channel) {
+  if (channel === 'red') {
+    channel = 0;
+  } else if (channel === 'green') {
+    channel = 1;
+  } else if (channel === 'blue') {
+    channel = 2;
+  }
+  if (is.integer(channel) && is.inRange(channel, 0, 4)) {
+    this.options.extractChannel = channel;
+  } else {
+    throw new Error('Cannot extract invalid channel ' + channel);
+  }
+  return this;
+}
+
+/**
+ * Join one or more channels to the image.
+ * The meaning of the added channels depends on the output colourspace, set with `toColourspace()`.
+ * By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+ * Channel ordering follows vips convention:
+ * - sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha.
+ * - CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha.
+ *
+ * Buffers may be any of the image formats supported by sharp: JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data.
+ * For raw pixel input, the `options` object should contain a `raw` attribute, which follows the format of the attribute of the same name in the `sharp()` constructor.
+ *
+ * @param {Array<String|Buffer>|String|Buffer} images - one or more images (file paths, Buffers).
+ * @param {Object} options - image options, see `sharp()` constructor.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function joinChannel (images, options) {
+  if (Array.isArray(images)) {
+    images.forEach(function (image) {
+      this.options.joinChannelIn.push(this._createInputDescriptor(image, options));
+    }, this);
+  } else {
+    this.options.joinChannelIn.push(this._createInputDescriptor(images, options));
+  }
+  return this;
+}
+
+/**
+ * Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.
+ *
+ * @example
+ * sharp('3-channel-rgb-input.png')
+ *   .bandbool(sharp.bool.and)
+ *   .toFile('1-channel-output.png', function (err, info) {
+ *     // The output will be a single channel image where each pixel `P = R & G & B`.
+ *     // If `I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111]`
+ *     // then `O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2`.
+ *   });
+ *
+ * @param {String} boolOp - one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function bandbool (boolOp) {
+  if (is.string(boolOp) && is.inArray(boolOp, ['and', 'or', 'eor'])) {
+    this.options.bandBoolOp = boolOp;
+  } else {
+    throw new Error('Invalid bandbool operation ' + boolOp);
+  }
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with channel-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  // Public instance functions
+  [
+    removeAlpha,
+    extractChannel,
+    joinChannel,
+    bandbool
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.bool = bool;
+};

lib/colour.js

@@ -0,0 +1,143 @@
+'use strict';
+
+const deprecate = require('util').deprecate;
+
+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'
+};
+
+/**
+ * @deprecated
+ * @private
+ */
+function background (rgba) {
+  const colour = color(rgba);
+  const background = [
+    colour.red(),
+    colour.green(),
+    colour.blue(),
+    Math.round(colour.alpha() * 255)
+  ];
+  this.options.resizeBackground = background;
+  this.options.extendBackground = background;
+  this.options.flattenBackground = background.slice(0, 3);
+  return this;
+}
+
+/**
+ * Tint the image using the provided chroma while preserving the image luminance.
+ * An alpha channel may be present and will be unchanged by the operation.
+ *
+ * @param {String|Object} rgb - parsed by the [color](https://www.npmjs.org/package/color) module to extract chroma values.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameter
+ */
+function tint (rgb) {
+  const colour = color(rgb);
+  this.options.tintA = colour.a();
+  this.options.tintB = colour.b();
+  return this;
+}
+
+/**
+ * Convert to 8-bit greyscale; 256 shades of grey.
+ * This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use `gamma()` with `greyscale()` for the best results.
+ * By default the output image will be web-friendly sRGB and contain three (identical) color channels.
+ * This may be overridden by other sharp operations such as `toColourspace('b-w')`,
+ * which will produce an output image containing one color channel.
+ * An alpha channel may be present, and will be unchanged by the operation.
+ * @param {Boolean} [greyscale=true]
+ * @returns {Sharp}
+ */
+function greyscale (greyscale) {
+  this.options.greyscale = is.bool(greyscale) ? greyscale : true;
+  return this;
+}
+
+/**
+ * Alternative spelling of `greyscale`.
+ * @param {Boolean} [grayscale=true]
+ * @returns {Sharp}
+ */
+function grayscale (grayscale) {
+  return this.greyscale(grayscale);
+}
+
+/**
+ * Set the output colourspace.
+ * By default output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
+ * @param {String} [colourspace] - output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568)
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function toColourspace (colourspace) {
+  if (!is.string(colourspace)) {
+    throw new Error('Invalid output colourspace ' + colourspace);
+  }
+  this.options.colourspace = colourspace;
+  return this;
+}
+
+/**
+ * Alternative spelling of `toColourspace`.
+ * @param {String} [colorspace] - output colorspace.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function toColorspace (colorspace) {
+  return this.toColourspace(colorspace);
+}
+
+/**
+ * Update a colour attribute of the this.options Object.
+ * @private
+ * @param {String} key
+ * @param {String|Object} val
+ * @throws {Error} Invalid key
+ */
+function _setColourOption (key, val) {
+  if (is.object(val) || is.string(val)) {
+    const colour = color(val);
+    this.options[key] = [
+      colour.red(),
+      colour.green(),
+      colour.blue(),
+      Math.round(colour.alpha() * 255)
+    ];
+  }
+}
+
+/**
+ * Decorate the Sharp prototype with colour-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    // Public
+    tint,
+    greyscale,
+    grayscale,
+    toColourspace,
+    toColorspace,
+    // Private
+    _setColourOption
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.colourspace = colourspace;
+  Sharp.colorspace = colourspace;
+  // Deprecated
+  Sharp.prototype.background = deprecate(background, 'background(background) is deprecated, use resize({ background }), extend({ background }) or flatten({ background }) instead');
+};

lib/composite.js

@@ -0,0 +1,96 @@
+'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`.
+ *
+ * If the overlay image contains an alpha channel then composition with premultiplication will occur.
+ *
+ * @example
+ * sharp('input.png')
+ *   .rotate(180)
+ *   .resize(300)
+ *   .flatten()
+ *   .background('#ff6600')
+ *   .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
+ *   .sharpen()
+ *   .withMetadata()
+ *   .webp( { quality: 90 } )
+ *   .toBuffer()
+ *   .then(function(outputBuffer) {
+ *     // outputBuffer contains upside down, 300px wide, alpha channel flattened
+ *     // onto orange background, composited with overlay.png with SE gravity,
+ *     // sharpened, with metadata, 90% quality WebP image data. Phew!
+ *   });
+ *
+ * @param {(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 {Number} [options.density=72] - number representing the DPI for vector overlay image.
+ * @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]
+ * @param {Object} [options.create] - describes a blank overlay to be created.
+ * @param {Number} [options.create.width]
+ * @param {Number} [options.create.height]
+ * @param {Number} [options.create.channels] - 3-4
+ * @param {String|Object} [options.create.background] - parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+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) && options.left >= 0 && is.integer(options.top) && options.top >= 0) {
+        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 +1,236 @@
+'use strict';
+
+const path = require('path');
+const util = require('util');
+const stream = require('stream');
+const events = require('events');
+const is = require('./is');
+
+require('./libvips').hasVendoredLibvips();
+const sharp = require('../build/Release/sharp.node');
+
+// Use NODE_DEBUG=sharp to enable libvips warnings
+const debuglog = util.debuglog('sharp');
+
+/**
+ * @class Sharp
+ *
+ * Constructor factory to create an instance of `sharp`, to which further methods are chained.
+ *
+ * JPEG, PNG, WebP or TIFF format image data can be streamed out from this object.
+ * When using Stream based output, derived attributes are available from the `info` event.
+ *
+ * Implements the [stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
+ *
+ * @example
+ * sharp('input.jpg')
+ *   .resize(300, 200)
+ *   .toFile('output.jpg', function(err) {
+ *     // output.jpg is a 300 pixels wide and 200 pixels high image
+ *     // containing a scaled and cropped version of input.jpg
+ *   });
+ *
+ * @example
+ * // Read image data from readableStream,
+ * // resize to 300 pixels wide,
+ * // emit an 'info' event with calculated dimensions
+ * // and finally write image data to writableStream
+ * var transformer = sharp()
+ *   .resize(300)
+ *   .on('info', function(info) {
+ *     console.log('Image height is ' + info.height);
+ *   });
+ * readableStream.pipe(transformer).pipe(writableStream);
+ *
+ * @example
+ * // Create a blank 300x200 PNG image of semi-transluent red pixels
+ * sharp({
+ *   create: {
+ *     width: 300,
+ *     height: 200,
+ *     channels: 4,
+ *     background: { r: 255, g: 0, b: 0, alpha: 0.5 }
+ *   }
+ * })
+ * .png()
+ * .toBuffer()
+ * .then( ... );
+ *
+ * @param {(Buffer|String)} [input] - if present, can be
+ *  a Buffer containing JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data, or
+ *  a String containing the path to an JPEG, PNG, WebP, GIF, SVG or TIFF image file.
+ *  JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data can be streamed into the object when not present.
+ * @param {Object} [options] - if present, is an Object with optional attributes.
+ * @param {Boolean} [options.failOnError=false] - by default apply a "best effort"
+ *  to decode images, even if the data is corrupt or invalid. Set this flag to true
+ *  if you'd rather halt processing and raise an error when loading invalid images.
+ * @param {Number} [options.density=72] - number representing the DPI for vector images.
+ * @param {Number} [options.page=0] - page number to extract for multi-page input (GIF, TIFF)
+ * @param {Object} [options.raw] - describes raw pixel input image data. See `raw()` for pixel ordering.
+ * @param {Number} [options.raw.width]
+ * @param {Number} [options.raw.height]
+ * @param {Number} [options.raw.channels] - 1-4
+ * @param {Object} [options.create] - describes a new image to be created.
+ * @param {Number} [options.create.width]
+ * @param {Number} [options.create.height]
+ * @param {Number} [options.create.channels] - 3-4
+ * @param {String|Object} [options.create.background] - parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+const Sharp = function (input, options) {
+  if (arguments.length === 1 && !is.defined(input)) {
+    throw new Error('Invalid input');
+  }
+  if (!(this instanceof Sharp)) {
+    return new Sharp(input, options);
+  }
+  stream.Duplex.call(this);
+  this.options = {
+    // input options
+    sequentialRead: false,
+    limitInputPixels: Math.pow(0x3FFF, 2),
+    // ICC profiles
+    iccProfilePath: path.join(__dirname, 'icc') + path.sep,
+    // resize options
+    topOffsetPre: -1,
+    leftOffsetPre: -1,
+    widthPre: -1,
+    heightPre: -1,
+    topOffsetPost: -1,
+    leftOffsetPost: -1,
+    widthPost: -1,
+    heightPost: -1,
+    width: -1,
+    height: -1,
+    canvas: 'crop',
+    position: 0,
+    resizeBackground: [0, 0, 0, 255],
+    useExifOrientation: false,
+    angle: 0,
+    rotationAngle: 0,
+    rotationBackground: [0, 0, 0, 255],
+    rotateBeforePreExtract: false,
+    flip: false,
+    flop: false,
+    extendTop: 0,
+    extendBottom: 0,
+    extendLeft: 0,
+    extendRight: 0,
+    extendBackground: [0, 0, 0, 255],
+    withoutEnlargement: false,
+    kernel: 'lanczos3',
+    fastShrinkOnLoad: true,
+    // operations
+    tintA: 128,
+    tintB: 128,
+    flatten: false,
+    flattenBackground: [0, 0, 0],
+    negate: false,
+    medianSize: 0,
+    blurSigma: 0,
+    sharpenSigma: 0,
+    sharpenFlat: 1,
+    sharpenJagged: 2,
+    threshold: 0,
+    thresholdGrayscale: true,
+    trimThreshold: 0,
+    gamma: 0,
+    greyscale: false,
+    normalise: 0,
+    booleanBufferIn: null,
+    booleanFileIn: '',
+    joinChannelIn: [],
+    extractChannel: -1,
+    removeAlpha: false,
+    colourspace: 'srgb',
+    // overlay
+    overlayGravity: 0,
+    overlayXOffset: -1,
+    overlayYOffset: -1,
+    overlayTile: false,
+    overlayCutout: false,
+    // output
+    fileOut: '',
+    formatOut: 'input',
+    streamOut: false,
+    withMetadata: false,
+    withMetadataOrientation: -1,
+    resolveWithObject: false,
+    // output format
+    jpegQuality: 80,
+    jpegProgressive: false,
+    jpegChromaSubsampling: '4:2:0',
+    jpegTrellisQuantisation: false,
+    jpegOvershootDeringing: false,
+    jpegOptimiseScans: false,
+    jpegOptimiseCoding: true,
+    jpegQuantisationTable: 0,
+    pngProgressive: false,
+    pngCompressionLevel: 9,
+    pngAdaptiveFiltering: false,
+    webpQuality: 80,
+    webpAlphaQuality: 100,
+    webpLossless: false,
+    webpNearLossless: false,
+    tiffQuality: 80,
+    tiffCompression: 'jpeg',
+    tiffPredictor: 'horizontal',
+    tiffSquash: false,
+    tiffXres: 1.0,
+    tiffYres: 1.0,
+    tileSize: 256,
+    tileOverlap: 0,
+    linearA: 1,
+    linearB: 0,
+    // Function to notify of libvips warnings
+    debuglog: debuglog,
+    // Function to notify of queue length changes
+    queueListener: function (queueLength) {
+      queue.emit('change', queueLength);
+    }
+  };
+  this.options.input = this._createInputDescriptor(input, options, { allowStream: true });
+  return this;
+};
+util.inherits(Sharp, stream.Duplex);
+
+/**
+ * An EventEmitter that emits a `change` event when a task is either:
+ * - queued, waiting for _libuv_ to provide a worker thread
+ * - complete
+ * @member
+ * @example
+ * sharp.queue.on('change', function(queueLength) {
+ *   console.log('Queue contains ' + queueLength + ' task(s)');
+ * });
+ */
+const queue = new events.EventEmitter();
+Sharp.queue = queue;
+
+/**
+ * An Object containing nested boolean values representing the available input and output formats/methods.
+ * @example
+ * console.log(sharp.format);
+ * @returns {Object}
+ */
+Sharp.format = sharp.format();
+
+/**
+ * An Object containing the version numbers of libvips and its dependencies.
+ * @member
+ * @example
+ * console.log(sharp.versions);
+ */
+Sharp.versions = {
+  vips: sharp.libvipsVersion()
+};
+try {
+  Sharp.versions = require('../vendor/versions.json');
+} catch (err) {}
+
+/**
+ * Export constructor.
+ * @private
+ */
+module.exports = Sharp;

lib/index.js

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

lib/input.js

@@ -0,0 +1,380 @@
+'use strict';
+
+const color = require('color');
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Create Object containing input and input-related options.
+ * @private
+ */
+function _createInputDescriptor (input, inputOptions, containerOptions) {
+  const inputDescriptor = { failOnError: false };
+  if (is.string(input)) {
+    // filesystem
+    inputDescriptor.file = input;
+  } else if (is.buffer(input)) {
+    // Buffer
+    inputDescriptor.buffer = input;
+  } else if (is.plainObject(input) && !is.defined(inputOptions)) {
+    // Plain Object descriptor, e.g. create
+    inputOptions = input;
+  } else if (!is.defined(input) && is.object(containerOptions) && containerOptions.allowStream) {
+    // Stream
+    inputDescriptor.buffer = [];
+  } else {
+    throw new Error('Unsupported input ' + typeof input);
+  }
+  if (is.object(inputOptions)) {
+    // Fail on error
+    if (is.defined(inputOptions.failOnError)) {
+      if (is.bool(inputOptions.failOnError)) {
+        inputDescriptor.failOnError = inputOptions.failOnError;
+      } else {
+        throw new Error('Invalid failOnError (boolean) ' + inputOptions.failOnError);
+      }
+    }
+    // Density
+    if (is.defined(inputOptions.density)) {
+      if (is.inRange(inputOptions.density, 1, 2400)) {
+        inputDescriptor.density = inputOptions.density;
+      } else {
+        throw new Error('Invalid density (1 to 2400) ' + inputOptions.density);
+      }
+    }
+    // Raw pixel input
+    if (is.defined(inputOptions.raw)) {
+      if (
+        is.object(inputOptions.raw) &&
+        is.integer(inputOptions.raw.width) && inputOptions.raw.width > 0 &&
+        is.integer(inputOptions.raw.height) && inputOptions.raw.height > 0 &&
+        is.integer(inputOptions.raw.channels) && is.inRange(inputOptions.raw.channels, 1, 4)
+      ) {
+        inputDescriptor.rawWidth = inputOptions.raw.width;
+        inputDescriptor.rawHeight = inputOptions.raw.height;
+        inputDescriptor.rawChannels = inputOptions.raw.channels;
+      } else {
+        throw new Error('Expected width, height and channels for raw pixel input');
+      }
+    }
+    // Page input for multi-page TIFF
+    if (is.defined(inputOptions.page)) {
+      if (is.integer(inputOptions.page) && is.inRange(inputOptions.page, 0, 100000)) {
+        inputDescriptor.page = inputOptions.page;
+      }
+    }
+    // Create new image
+    if (is.defined(inputOptions.create)) {
+      if (
+        is.object(inputOptions.create) &&
+        is.integer(inputOptions.create.width) && inputOptions.create.width > 0 &&
+        is.integer(inputOptions.create.height) && inputOptions.create.height > 0 &&
+        is.integer(inputOptions.create.channels) && is.inRange(inputOptions.create.channels, 3, 4) &&
+        is.defined(inputOptions.create.background)
+      ) {
+        inputDescriptor.createWidth = inputOptions.create.width;
+        inputDescriptor.createHeight = inputOptions.create.height;
+        inputDescriptor.createChannels = inputOptions.create.channels;
+        const background = color(inputOptions.create.background);
+        inputDescriptor.createBackground = [
+          background.red(),
+          background.green(),
+          background.blue(),
+          Math.round(background.alpha() * 255)
+        ];
+        delete inputDescriptor.buffer;
+      } else {
+        throw new Error('Expected width, height, channels and background to create a new input image');
+      }
+    }
+  } else if (is.defined(inputOptions)) {
+    throw new Error('Invalid input options ' + inputOptions);
+  }
+  return inputDescriptor;
+}
+
+/**
+ * Handle incoming Buffer chunk on Writable Stream.
+ * @private
+ * @param {Buffer} chunk
+ * @param {String} encoding - unused
+ * @param {Function} callback
+ */
+function _write (chunk, encoding, callback) {
+  /* istanbul ignore else */
+  if (Array.isArray(this.options.input.buffer)) {
+    /* istanbul ignore else */
+    if (is.buffer(chunk)) {
+      if (this.options.input.buffer.length === 0) {
+        const that = this;
+        this.on('finish', function () {
+          that.streamInFinished = true;
+        });
+      }
+      this.options.input.buffer.push(chunk);
+      callback();
+    } else {
+      callback(new Error('Non-Buffer data on Writable Stream'));
+    }
+  } else {
+    callback(new Error('Unexpected data on Writable Stream'));
+  }
+}
+
+/**
+ * Flattens the array of chunks accumulated in input.buffer.
+ * @private
+ */
+function _flattenBufferIn () {
+  if (this._isStreamInput()) {
+    this.options.input.buffer = Buffer.concat(this.options.input.buffer);
+  }
+}
+
+/**
+ * Are we expecting Stream-based input?
+ * @private
+ * @returns {Boolean}
+ */
+function _isStreamInput () {
+  return Array.isArray(this.options.input.buffer);
+}
+
+/**
+ * Take a "snapshot" of the Sharp instance, returning a new instance.
+ * Cloned instances inherit the input of their parent instance.
+ * This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.
+ *
+ * @example
+ * const pipeline = sharp().rotate();
+ * pipeline.clone().resize(800, 600).pipe(firstWritableStream);
+ * pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
+ * readableStream.pipe(pipeline);
+ * // firstWritableStream receives auto-rotated, resized readableStream
+ * // secondWritableStream receives auto-rotated, extracted region of readableStream
+ *
+ * @returns {Sharp}
+ */
+function clone () {
+  const that = this;
+  // Clone existing options
+  const clone = this.constructor.call();
+  clone.options = Object.assign({}, this.options);
+  // Pass 'finish' event to clone for Stream-based input
+  if (this._isStreamInput()) {
+    this.on('finish', function () {
+      // Clone inherits input data
+      that._flattenBufferIn();
+      clone.options.bufferIn = that.options.bufferIn;
+      clone.emit('finish');
+    });
+  }
+  return clone;
+}
+
+/**
+ * Fast access to (uncached) image metadata without decoding any compressed image data.
+ * A 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`
+ * - `size`: Total size of image in bytes, for Stream and Buffer input only
+ * - `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
+ * - `height`: Number of pixels high (EXIF orientation is not taken into consideration)
+ * - `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636)
+ * - `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
+ * - `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...](https://github.com/libvips/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672)
+ * - `density`: Number of pixels per inch (DPI), if present
+ * - `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
+ * - `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+ * - `hasProfile`: Boolean indicating the presence of an embedded ICC profile
+ * - `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
+ * - `orientation`: Number value of the EXIF Orientation header, if present
+ * - `exif`: Buffer containing raw EXIF data, if present
+ * - `icc`: Buffer containing raw [ICC](https://www.npmjs.com/package/icc) profile data, if present
+ * - `iptc`: Buffer containing raw IPTC data, if present
+ * - `xmp`: Buffer containing raw XMP data, if present
+ *
+ * @example
+ * const image = sharp(inputJpg);
+ * image
+ *   .metadata()
+ *   .then(function(metadata) {
+ *     return image
+ *       .resize(Math.round(metadata.width / 2))
+ *       .webp()
+ *       .toBuffer();
+ *   })
+ *   .then(function(data) {
+ *     // data contains a WebP image half the width and height of the original JPEG
+ *   });
+ *
+ * @param {Function} [callback] - called with the arguments `(err, metadata)`
+ * @returns {Promise<Object>|Sharp}
+ */
+function metadata (callback) {
+  const that = this;
+  if (is.fn(callback)) {
+    if (this._isStreamInput()) {
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.metadata(that.options, callback);
+      });
+    } else {
+      sharp.metadata(this.options, callback);
+    }
+    return this;
+  } else {
+    if (this._isStreamInput()) {
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.metadata(that.options, function (err, metadata) {
+            if (err) {
+              reject(err);
+            } else {
+              resolve(metadata);
+            }
+          });
+        });
+      });
+    } else {
+      return new Promise(function (resolve, reject) {
+        sharp.metadata(that.options, function (err, metadata) {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(metadata);
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Access to pixel-derived image statistics for every channel in the image.
+ * A Promise is returned when `callback` is not provided.
+ *
+ * - `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
+ *     - `min` (minimum value in the channel)
+ *     - `max` (maximum value in the channel)
+ *     - `sum` (sum of all values in a channel)
+ *     - `squaresSum` (sum of squared values in a channel)
+ *     - `mean` (mean of the values in a channel)
+ *     - `stdev` (standard deviation for the values in a channel)
+ *     - `minX` (x-coordinate of one of the pixel where the minimum lies)
+ *     - `minY` (y-coordinate of one of the pixel where the minimum lies)
+ *     - `maxX` (x-coordinate of one of the pixel where the maximum lies)
+ *     - `maxY` (y-coordinate of one of the pixel where the maximum lies)
+ * - `isOpaque`: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel
+ * - `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
+ *
+ * @example
+ * const image = sharp(inputJpg);
+ * image
+ *   .stats()
+ *   .then(function(stats) {
+ *      // stats contains the channel-wise statistics array and the isOpaque value
+ *   });
+ *
+ * @param {Function} [callback] - called with the arguments `(err, stats)`
+ * @returns {Promise<Object>}
+ */
+function stats (callback) {
+  const that = this;
+  if (is.fn(callback)) {
+    if (this._isStreamInput()) {
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.stats(that.options, callback);
+      });
+    } else {
+      sharp.stats(this.options, callback);
+    }
+    return this;
+  } else {
+    if (this._isStreamInput()) {
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.stats(that.options, function (err, stats) {
+            if (err) {
+              reject(err);
+            } else {
+              resolve(stats);
+            }
+          });
+        });
+      });
+    } else {
+      return new Promise(function (resolve, reject) {
+        sharp.stats(that.options, function (err, stats) {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(stats);
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Do not process input images where the number of pixels (width * 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
+*/
+function limitInputPixels (limit) {
+  // if we pass in false we represent the integer as 0 to disable
+  if (limit === false) {
+    limit = 0;
+  } else if (limit === true) {
+    limit = Math.pow(0x3FFF, 2);
+  }
+  if (is.integer(limit) && limit >= 0) {
+    this.options.limitInputPixels = limit;
+  } else {
+    throw is.invalidParameterError('limitInputPixels', 'integer', limit);
+  }
+  return this;
+}
+
+/**
+ * An advanced setting that switches the libvips access method to `VIPS_ACCESS_SEQUENTIAL`.
+ * This will reduce memory usage and can improve performance on some systems.
+ *
+ * The default behaviour *before* function call is `false`, meaning the libvips access method is not sequential.
+ *
+ * @param {Boolean} [sequentialRead=true]
+ * @returns {Sharp}
+ */
+function sequentialRead (sequentialRead) {
+  this.options.sequentialRead = is.bool(sequentialRead) ? sequentialRead : true;
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with input-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    // Private
+    _createInputDescriptor,
+    _write,
+    _flattenBufferIn,
+    _isStreamInput,
+    // Public
+    clone,
+    metadata,
+    stats,
+    limitInputPixels,
+    sequentialRead
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+};

lib/is.js

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

lib/libvips.js

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

lib/operation.js

@@ -0,0 +1,392 @@
+'use strict';
+
+const color = require('color');
+const is = require('./is');
+
+/**
+ * Rotate the output image by either an explicit angle
+ * or auto-orient based on the EXIF `Orientation` tag.
+ *
+ * If an angle is provided, it is converted to a valid positive degree rotation.
+ * For example, `-450` will produce a 270deg rotation.
+ *
+ * When rotating by an angle other than a multiple of 90,
+ * the background colour can be provided with the `background` option.
+ *
+ * If no angle is provided, it is determined from the EXIF data.
+ * Mirroring is supported and may infer the use of a flip operation.
+ *
+ * The use of `rotate` implies the removal of the EXIF `Orientation` tag, if any.
+ *
+ * Method order is important when both rotating and extracting regions,
+ * for example `rotate(x).extract(y)` will produce a different result to `extract(y).rotate(x)`.
+ *
+ * @example
+ * const pipeline = sharp()
+ *   .rotate()
+ *   .resize(null, 200)
+ *   .toBuffer(function (err, outputBuffer, info) {
+ *     // outputBuffer contains 200px high JPEG image data,
+ *     // auto-rotated using EXIF Orientation tag
+ *     // info.width and info.height contain the dimensions of the resized image
+ *   });
+ * readableStream.pipe(pipeline);
+ *
+ * @param {Number} [angle=auto] angle of rotation.
+ * @param {Object} [options] - if present, is an Object with optional attributes.
+ * @param {String|Object} [options.background="#000000"] parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function rotate (angle, options) {
+  if (!is.defined(angle)) {
+    this.options.useExifOrientation = true;
+  } else if (is.integer(angle) && !(angle % 90)) {
+    this.options.angle = angle;
+  } else if (is.number(angle)) {
+    this.options.rotationAngle = angle;
+    if (is.object(options) && options.background) {
+      const backgroundColour = color(options.background);
+      this.options.rotationBackground = [
+        backgroundColour.red(),
+        backgroundColour.green(),
+        backgroundColour.blue(),
+        Math.round(backgroundColour.alpha() * 255)
+      ];
+    }
+  } else {
+    throw new Error('Unsupported angle: must be a number.');
+  }
+  return this;
+}
+
+/**
+ * Flip the image about the vertical Y axis. This always occurs after rotation, if any.
+ * The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.
+ * @param {Boolean} [flip=true]
+ * @returns {Sharp}
+ */
+function flip (flip) {
+  this.options.flip = is.bool(flip) ? flip : true;
+  return this;
+}
+
+/**
+ * Flop the image about the horizontal X axis. This always occurs after rotation, if any.
+ * The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.
+ * @param {Boolean} [flop=true]
+ * @returns {Sharp}
+ */
+function flop (flop) {
+  this.options.flop = is.bool(flop) ? flop : true;
+  return this;
+}
+
+/**
+ * Sharpen the image.
+ * When used without parameters, performs a fast, mild sharpen of the output image.
+ * When a `sigma` is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space.
+ * Separate control over the level of sharpening in "flat" and "jagged" areas is available.
+ *
+ * @param {Number} [sigma] - the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+ * @param {Number} [flat=1.0] - the level of sharpening to apply to "flat" areas.
+ * @param {Number} [jagged=2.0] - the level of sharpening to apply to "jagged" areas.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function sharpen (sigma, flat, jagged) {
+  if (!is.defined(sigma)) {
+    // No arguments: default to mild sharpen
+    this.options.sharpenSigma = -1;
+  } else if (is.bool(sigma)) {
+    // Boolean argument: apply mild sharpen?
+    this.options.sharpenSigma = sigma ? -1 : 0;
+  } else if (is.number(sigma) && is.inRange(sigma, 0.01, 10000)) {
+    // Numeric argument: specific sigma
+    this.options.sharpenSigma = sigma;
+    // Control over flat areas
+    if (is.defined(flat)) {
+      if (is.number(flat) && is.inRange(flat, 0, 10000)) {
+        this.options.sharpenFlat = flat;
+      } else {
+        throw new Error('Invalid sharpen level for flat areas (0.0 - 10000.0) ' + flat);
+      }
+    }
+    // Control over jagged areas
+    if (is.defined(jagged)) {
+      if (is.number(jagged) && is.inRange(jagged, 0, 10000)) {
+        this.options.sharpenJagged = jagged;
+      } else {
+        throw new Error('Invalid sharpen level for jagged areas (0.0 - 10000.0) ' + jagged);
+      }
+    }
+  } else {
+    throw new Error('Invalid sharpen sigma (0.01 - 10000) ' + sigma);
+  }
+  return this;
+}
+
+/**
+ * Apply median filter.
+ * When used without parameters the default window is 3x3.
+ * @param {Number} [size=3] square mask size: size x size
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function median (size) {
+  if (!is.defined(size)) {
+    // No arguments: default to 3x3
+    this.options.medianSize = 3;
+  } else if (is.integer(size) && is.inRange(size, 1, 1000)) {
+    // Numeric argument: specific sigma
+    this.options.medianSize = size;
+  } else {
+    throw new Error('Invalid median size ' + size);
+  }
+  return this;
+}
+
+/**
+ * Blur the image.
+ * When used without parameters, performs a fast, mild blur of the output image.
+ * When a `sigma` is provided, performs a slower, more accurate Gaussian blur.
+ * @param {Number} [sigma] a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function blur (sigma) {
+  if (!is.defined(sigma)) {
+    // No arguments: default to mild blur
+    this.options.blurSigma = -1;
+  } else if (is.bool(sigma)) {
+    // Boolean argument: apply mild blur?
+    this.options.blurSigma = sigma ? -1 : 0;
+  } else if (is.number(sigma) && is.inRange(sigma, 0.3, 1000)) {
+    // Numeric argument: specific sigma
+    this.options.blurSigma = sigma;
+  } else {
+    throw new Error('Invalid blur sigma (0.3 - 1000.0) ' + sigma);
+  }
+  return this;
+}
+
+/**
+ * Merge alpha transparency channel, if any, with a background.
+ * @param {String|Object} [options.background={r: 0, g: 0, b: 0}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black.
+ * @returns {Sharp}
+ */
+function flatten (options) {
+  this.options.flatten = is.bool(options) ? options : true;
+  if (is.object(options)) {
+    this._setColourOption('flattenBackground', options.background);
+  }
+  return this;
+}
+
+/**
+ * Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of `1/gamma`
+ * then increasing the encoding (brighten) post-resize at a factor of `gamma`.
+ * This can improve the perceived brightness of a resized image in non-linear colour spaces.
+ * JPEG and WebP input images will not take advantage of the shrink-on-load performance optimisation
+ * when applying a gamma correction.
+ * @param {Number} [gamma=2.2] value between 1.0 and 3.0.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+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}
+ */
+function negate (negate) {
+  this.options.negate = is.bool(negate) ? negate : true;
+  return this;
+}
+
+/**
+ * Enhance output image contrast by stretching its luminance to cover the full dynamic range.
+ * @param {Boolean} [normalise=true]
+ * @returns {Sharp}
+ */
+function normalise (normalise) {
+  this.options.normalise = is.bool(normalise) ? normalise : true;
+  return this;
+}
+
+/**
+ * Alternative spelling of normalise.
+ * @param {Boolean} [normalize=true]
+ * @returns {Sharp}
+ */
+function normalize (normalize) {
+  return this.normalise(normalize);
+}
+
+/**
+ * Convolve the image with the specified kernel.
+ *
+ * @example
+ * sharp(input)
+ *   .convolve({
+ *     width: 3,
+ *     height: 3,
+ *     kernel: [-1, 0, 1, -2, 0, 2, -1, 0, 1]
+ *   })
+ *   .raw()
+ *   .toBuffer(function(err, data, info) {
+ *     // data contains the raw pixel data representing the convolution
+ *     // of the input image with the horizontal Sobel operator
+ *   });
+ *
+ * @param {Object} kernel
+ * @param {Number} kernel.width - width of the kernel in pixels.
+ * @param {Number} kernel.height - width of the kernel in pixels.
+ * @param {Array<Number>} kernel.kernel - Array of length `width*height` containing the kernel values.
+ * @param {Number} [kernel.scale=sum] - the scale of the kernel in pixels.
+ * @param {Number} [kernel.offset=0] - the offset of the kernel in pixels.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function convolve (kernel) {
+  if (!is.object(kernel) || !Array.isArray(kernel.kernel) ||
+      !is.integer(kernel.width) || !is.integer(kernel.height) ||
+      !is.inRange(kernel.width, 3, 1001) || !is.inRange(kernel.height, 3, 1001) ||
+      kernel.height * kernel.width !== kernel.kernel.length
+  ) {
+    // must pass in a kernel
+    throw new Error('Invalid convolution kernel');
+  }
+  // Default scale is sum of kernel values
+  if (!is.integer(kernel.scale)) {
+    kernel.scale = kernel.kernel.reduce(function (a, b) {
+      return a + b;
+    }, 0);
+  }
+  // Clip scale to a minimum value of 1
+  if (kernel.scale < 1) {
+    kernel.scale = 1;
+  }
+  if (!is.integer(kernel.offset)) {
+    kernel.offset = 0;
+  }
+  this.options.convKernel = kernel;
+  return this;
+}
+
+/**
+ * Any pixel value greather than or equal to the threshold value will be set to 255, otherwise it will be set to 0.
+ * @param {Number} [threshold=128] - a value in the range 0-255 representing the level at which the threshold will be applied.
+ * @param {Object} [options]
+ * @param {Boolean} [options.greyscale=true] - convert to single channel greyscale.
+ * @param {Boolean} [options.grayscale=true] - alternative spelling for greyscale.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function threshold (threshold, options) {
+  if (!is.defined(threshold)) {
+    this.options.threshold = 128;
+  } else if (is.bool(threshold)) {
+    this.options.threshold = threshold ? 128 : 0;
+  } else if (is.integer(threshold) && is.inRange(threshold, 0, 255)) {
+    this.options.threshold = threshold;
+  } else {
+    throw new Error('Invalid threshold (0 to 255) ' + threshold);
+  }
+  if (!is.object(options) || options.greyscale === true || options.grayscale === true) {
+    this.options.thresholdGrayscale = true;
+  } else {
+    this.options.thresholdGrayscale = false;
+  }
+  return this;
+}
+
+/**
+ * Perform a bitwise boolean operation with operand image.
+ *
+ * This operation creates an output image where each pixel is the result of
+ * the selected bitwise boolean `operation` between the corresponding pixels of the input images.
+ *
+ * @param {Buffer|String} operand - Buffer containing image data or String containing the path to an image file.
+ * @param {String} operator - one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+ * @param {Object} [options]
+ * @param {Object} [options.raw] - describes operand when using raw pixel data.
+ * @param {Number} [options.raw.width]
+ * @param {Number} [options.raw.height]
+ * @param {Number} [options.raw.channels]
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function boolean (operand, operator, options) {
+  this.options.boolean = this._createInputDescriptor(operand, options);
+  if (is.string(operator) && is.inArray(operator, ['and', 'or', 'eor'])) {
+    this.options.booleanOp = operator;
+  } else {
+    throw new Error('Invalid boolean operator ' + operator);
+  }
+  return this;
+}
+
+/**
+ * Apply the linear formula a * input + b to the image (levels adjustment)
+ * @param {Number} [a=1.0] multiplier
+ * @param {Number} [b=0.0] offset
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function linear (a, b) {
+  if (!is.defined(a)) {
+    this.options.linearA = 1.0;
+  } else if (is.number(a)) {
+    this.options.linearA = a;
+  } else {
+    throw new Error('Invalid linear transform multiplier ' + a);
+  }
+
+  if (!is.defined(b)) {
+    this.options.linearB = 0.0;
+  } else if (is.number(b)) {
+    this.options.linearB = b;
+  } else {
+    throw new Error('Invalid linear transform offset ' + b);
+  }
+
+  return this;
+}
+
+/**
+ * Decorate the Sharp prototype with operation-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    rotate,
+    flip,
+    flop,
+    sharpen,
+    median,
+    blur,
+    flatten,
+    gamma,
+    negate,
+    normalise,
+    normalize,
+    convolve,
+    threshold,
+    boolean,
+    linear
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+};

lib/output.js

@@ -0,0 +1,664 @@
+'use strict';
+
+const is = require('./is');
+const sharp = require('../build/Release/sharp.node');
+
+/**
+ * Write output image data to a file.
+ *
+ * If an explicit output format is not selected, it will be inferred from the extension,
+ * with JPEG, PNG, WebP, TIFF, DZI, and libvips' V format supported.
+ * Note that raw pixel data is only supported for buffer output.
+ *
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * @example
+ * sharp(input)
+ *   .toFile('output.png', (err, info) => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toFile('output.png')
+ *   .then(info => { ... })
+ *   .catch(err => { ... });
+ *
+ * @param {String} fileOut - the path to write the image data to.
+ * @param {Function} [callback] - called on completion with two arguments `(err, info)`.
+ * `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+ * `channels` and `premultiplied` (indicating if premultiplication was used).
+ * When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+ * @returns {Promise<Object>} - when no callback is provided
+ * @throws {Error} Invalid parameters
+ */
+function toFile (fileOut, callback) {
+  if (!fileOut || fileOut.length === 0) {
+    const errOutputInvalid = new Error('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, TIFF and RAW output are supported.
+ * By default, the format will match the input image, except GIF and SVG input which become PNG output.
+ *
+ * `callback`, if present, gets three arguments `(err, data, info)` where:
+ * - `err` is an error, if any.
+ * - `data` is the output image data.
+ * - `info` contains the output image `format`, `size` (bytes), `width`, `height`,
+ * `channels` and `premultiplied` (indicating if premultiplication was used).
+ * When using a crop strategy also contains `cropOffsetLeft` and `cropOffsetTop`.
+ *
+ * A `Promise` is returned when `callback` is not provided.
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer((err, data, info) => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer()
+ *   .then(data => { ... })
+ *   .catch(err => { ... });
+ *
+ * @example
+ * sharp(input)
+ *   .toBuffer({ resolveWithObject: true })
+ *   .then(({ data, info }) => { ... })
+ *   .catch(err => { ... });
+ *
+ * @param {Object} [options]
+ * @param {Boolean} [options.resolveWithObject] Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
+ * @param {Function} [callback]
+ * @returns {Promise<Buffer>} - when no callback is provided
+ */
+function toBuffer (options, callback) {
+  if (is.object(options)) {
+    if (is.bool(options.resolveWithObject)) {
+      this.options.resolveWithObject = options.resolveWithObject;
+    }
+  }
+  return this._pipeline(is.fn(options) ? options : callback);
+}
+
+/**
+ * Include all metadata (EXIF, XMP, IPTC) from the input image in the output image.
+ * The default behaviour, when `withMetadata` is not used, is to strip all metadata and convert to the device-independent sRGB colour space.
+ * This will also convert to and add a web-friendly sRGB ICC profile.
+ *
+ * @example
+ * sharp('input.jpg')
+ *   .withMetadata()
+ *   .toFile('output-with-metadata.jpg')
+ *   .then(info => { ... });
+ *
+ * @param {Object} [withMetadata]
+ * @param {Number} [withMetadata.orientation] value between 1 and 8, used to update the EXIF `Orientation` tag.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function withMetadata (withMetadata) {
+  this.options.withMetadata = is.bool(withMetadata) ? withMetadata : true;
+  if (is.object(withMetadata)) {
+    if (is.defined(withMetadata.orientation)) {
+      if (is.integer(withMetadata.orientation) && is.inRange(withMetadata.orientation, 1, 8)) {
+        this.options.withMetadataOrientation = withMetadata.orientation;
+      } else {
+        throw new Error('Invalid orientation (1 to 8) ' + withMetadata.orientation);
+      }
+    }
+  }
+  return this;
+}
+
+/**
+ * Use these JPEG options for output image.
+ *
+ * @example
+ * // Convert any input to very high quality JPEG output
+ * const data = await sharp(input)
+ *   .jpeg({
+ *     quality: 100,
+ *     chromaSubsampling: '4:4:4'
+ *   })
+ *   .toBuffer();
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Boolean} [options.progressive=false] - use progressive (interlace) scan
+ * @param {String} [options.chromaSubsampling='4:2:0'] - set to '4:4:4' to prevent chroma subsampling when quality <= 90
+ * @param {Boolean} [options.trellisQuantisation=false] - apply trellis quantisation, requires mozjpeg
+ * @param {Boolean} [options.overshootDeringing=false] - apply overshoot deringing, requires mozjpeg
+ * @param {Boolean} [options.optimiseScans=false] - optimise progressive scans, forces progressive, requires mozjpeg
+ * @param {Boolean} [options.optimizeScans=false] - alternative spelling of optimiseScans
+ * @param {Boolean} [options.optimiseCoding=true] - optimise Huffman coding tables
+ * @param {Boolean} [options.optimizeCoding=true] - alternative spelling of optimiseCoding
+ * @param {Number} [options.quantisationTable=0] - quantization table to use, integer 0-8, requires mozjpeg
+ * @param {Number} [options.quantizationTable=0] - alternative spelling of quantisationTable
+ * @param {Boolean} [options.force=true] - force JPEG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function jpeg (options) {
+  if (is.object(options)) {
+    if (is.defined(options.quality)) {
+      if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+        this.options.jpegQuality = options.quality;
+      } else {
+        throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+      }
+    }
+    if (is.defined(options.progressive)) {
+      this._setBooleanOption('jpegProgressive', options.progressive);
+    }
+    if (is.defined(options.chromaSubsampling)) {
+      if (is.string(options.chromaSubsampling) && is.inArray(options.chromaSubsampling, ['4:2:0', '4:4:4'])) {
+        this.options.jpegChromaSubsampling = options.chromaSubsampling;
+      } else {
+        throw new Error('Invalid chromaSubsampling (4:2:0, 4:4:4) ' + options.chromaSubsampling);
+      }
+    }
+    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;
+      }
+    }
+    options.optimiseCoding = is.bool(options.optimizeCoding) ? options.optimizeCoding : options.optimiseCoding;
+    if (is.defined(options.optimiseCoding)) {
+      this._setBooleanOption('jpegOptimiseCoding', options.optimiseCoding);
+    }
+    options.quantisationTable = is.number(options.quantizationTable) ? options.quantizationTable : options.quantisationTable;
+    if (is.defined(options.quantisationTable)) {
+      if (is.integer(options.quantisationTable) && is.inRange(options.quantisationTable, 0, 8)) {
+        this.options.jpegQuantisationTable = options.quantisationTable;
+      } else {
+        throw new Error('Invalid quantisation table (integer, 0-8) ' + options.quantisationTable);
+      }
+    }
+  }
+  return this._updateFormatOut('jpeg', options);
+}
+
+/**
+ * Use these PNG options for output image.
+ *
+ * PNG output is always full colour at 8 or 16 bits per pixel.
+ * Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.
+ *
+ * @example
+ * // Convert any input to PNG output
+ * const data = await sharp(input)
+ *   .png()
+ *   .toBuffer();
+ *
+ * @param {Object} [options]
+ * @param {Boolean} [options.progressive=false] - use progressive (interlace) scan
+ * @param {Number} [options.compressionLevel=9] - zlib compression level, 0-9
+ * @param {Boolean} [options.adaptiveFiltering=false] - use adaptive row filtering
+ * @param {Boolean} [options.force=true] - force PNG output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function png (options) {
+  if (is.object(options)) {
+    if (is.defined(options.progressive)) {
+      this._setBooleanOption('pngProgressive', options.progressive);
+    }
+    if (is.defined(options.compressionLevel)) {
+      if (is.integer(options.compressionLevel) && is.inRange(options.compressionLevel, 0, 9)) {
+        this.options.pngCompressionLevel = options.compressionLevel;
+      } else {
+        throw new Error('Invalid compressionLevel (integer, 0-9) ' + options.compressionLevel);
+      }
+    }
+    if (is.defined(options.adaptiveFiltering)) {
+      this._setBooleanOption('pngAdaptiveFiltering', options.adaptiveFiltering);
+    }
+  }
+  return this._updateFormatOut('png', options);
+}
+
+/**
+ * Use these WebP options for output image.
+ *
+ * @example
+ * // Convert any input to lossless WebP output
+ * const data = await sharp(input)
+ *   .webp({ lossless: true })
+ *   .toBuffer();
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Number} [options.alphaQuality=100] - quality of alpha layer, integer 0-100
+ * @param {Boolean} [options.lossless=false] - use lossless compression mode
+ * @param {Boolean} [options.nearLossless=false] - use near_lossless compression mode
+ * @param {Boolean} [options.force=true] - force WebP output, otherwise attempt to use input format
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function webp (options) {
+  if (is.object(options) && is.defined(options.quality)) {
+    if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+      this.options.webpQuality = options.quality;
+    } else {
+      throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+    }
+  }
+  if (is.object(options) && is.defined(options.alphaQuality)) {
+    if (is.integer(options.alphaQuality) && is.inRange(options.alphaQuality, 0, 100)) {
+      this.options.webpAlphaQuality = options.alphaQuality;
+    } else {
+      throw new Error('Invalid webp alpha quality (integer, 0-100) ' + options.alphaQuality);
+    }
+  }
+  if (is.object(options) && is.defined(options.lossless)) {
+    this._setBooleanOption('webpLossless', options.lossless);
+  }
+  if (is.object(options) && is.defined(options.nearLossless)) {
+    this._setBooleanOption('webpNearLossless', options.nearLossless);
+  }
+  return this._updateFormatOut('webp', options);
+}
+
+/**
+ * Use these TIFF options for output image.
+ *
+ * @example
+ * // Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
+ * sharp('input.svg')
+ *   .tiff({
+ *     compression: 'lzw',
+ *     squash: true
+ *   })
+ *   .toFile('1-bpp-output.tiff')
+ *   .then(info => { ... });
+ *
+ * @param {Object} [options] - output options
+ * @param {Number} [options.quality=80] - quality, integer 1-100
+ * @param {Boolean} [options.force=true] - force TIFF output, otherwise attempt to use input format
+ * @param {Boolean} [options.compression='jpeg'] - compression options: lzw, deflate, jpeg, ccittfax4
+ * @param {Boolean} [options.predictor='horizontal'] - compression predictor options: none, horizontal, float
+ * @param {Number} [options.xres=1.0] - horizontal resolution in pixels/mm
+ * @param {Number} [options.yres=1.0] - vertical resolution in pixels/mm
+ * @param {Boolean} [options.squash=false] - squash 8-bit images down to 1 bit
+ * @returns {Sharp}
+ * @throws {Error} Invalid options
+ */
+function tiff (options) {
+  if (is.object(options) && is.defined(options.quality)) {
+    if (is.integer(options.quality) && is.inRange(options.quality, 1, 100)) {
+      this.options.tiffQuality = options.quality;
+    } else {
+      throw new Error('Invalid quality (integer, 1-100) ' + options.quality);
+    }
+  }
+  if (is.object(options) && is.defined(options.squash)) {
+    if (is.bool(options.squash)) {
+      this.options.tiffSquash = options.squash;
+    } else {
+      throw new Error('Invalid Value for squash ' + options.squash + ' Only Boolean Values allowed for options.squash.');
+    }
+  }
+  // resolution
+  if (is.object(options) && is.defined(options.xres)) {
+    if (is.number(options.xres)) {
+      this.options.tiffXres = options.xres;
+    } else {
+      throw new Error('Invalid Value for xres ' + options.xres + ' Only numeric values allowed for options.xres');
+    }
+  }
+  if (is.object(options) && is.defined(options.yres)) {
+    if (is.number(options.yres)) {
+      this.options.tiffYres = options.yres;
+    } else {
+      throw new Error('Invalid Value for yres ' + options.yres + ' Only numeric values allowed for options.yres');
+    }
+  }
+  // compression
+  if (is.defined(options) && is.defined(options.compression)) {
+    if (is.string(options.compression) && is.inArray(options.compression, ['lzw', 'deflate', 'jpeg', 'ccittfax4', 'none'])) {
+      this.options.tiffCompression = options.compression;
+    } else {
+      const message = `Invalid compression option "${options.compression}". Should be one of: lzw, deflate, jpeg, ccittfax4, none`;
+      throw new Error(message);
+    }
+  }
+  // predictor
+  if (is.defined(options) && is.defined(options.predictor)) {
+    if (is.string(options.predictor) && is.inArray(options.predictor, ['none', 'horizontal', 'float'])) {
+      this.options.tiffPredictor = options.predictor;
+    } else {
+      const message = `Invalid predictor option "${options.predictor}". Should be one of: none, horizontal, float`;
+      throw new Error(message);
+    }
+  }
+  return this._updateFormatOut('tiff', options);
+}
+
+/**
+ * Force output to be raw, uncompressed uint8 pixel data.
+ *
+ * @example
+ * // Extract raw RGB pixel data from JPEG input
+ * const { data, info } = await sharp('input.jpg')
+ *   .raw()
+ *   .toBuffer({ resolveWithObject: true });
+ *
+ * @returns {Sharp}
+ */
+function raw () {
+  return this._updateFormatOut('raw');
+}
+
+/**
+ * Force output to a given format.
+ *
+ * @example
+ * // Convert any input to PNG output
+ * const data = await sharp(input)
+ *   .toFormat('png')
+ *   .toBuffer();
+ *
+ * @param {(String|Object)} format - as a String or an Object with an 'id' attribute
+ * @param {Object} options - output options
+ * @returns {Sharp}
+ * @throws {Error} unsupported format or options
+ */
+function toFormat (format, options) {
+  if (is.object(format) && is.string(format.id)) {
+    format = format.id;
+  }
+  if (format === 'jpg') format = 'jpeg';
+  if (!is.inArray(format, ['jpeg', 'png', 'webp', 'tiff', 'raw'])) {
+    throw new Error('Unsupported output format ' + format);
+  }
+  return this[format](options);
+}
+
+/**
+ * Use tile-based deep zoom (image pyramid) output.
+ * Set the format and options for tile images via the `toFormat`, `jpeg`, `png` or `webp` functions.
+ * Use a `.zip` or `.szi` file extension with `toFile` to write to a compressed archive file format.
+ *
+ * Warning: multiple sharp instances concurrently producing tile output can expose a possible race condition in some versions of libgsf.
+ *
+ * @example
+ *  sharp('input.tiff')
+ *   .png()
+ *   .tile({
+ *     size: 512
+ *   })
+ *   .toFile('output.dz', function(err, info) {
+ *     // output.dzi is the Deep Zoom XML definition
+ *     // output_files contains 512x512 tiles grouped by zoom level
+ *   });
+ *
+ * @param {Object} [tile]
+ * @param {Number} [tile.size=256] tile size in pixels, a value between 1 and 8192.
+ * @param {Number} [tile.overlap=0] tile overlap in pixels, a value between 0 and 8192.
+ * @param {Number} [tile.angle=0] tile angle of rotation, must be a multiple of 90.
+ * @param {String} [tile.depth] how deep to make the pyramid, possible values are `onepixel`, `onetile` or `one`, default based on layout.
+ * @param {String} [tile.container='fs'] tile container, with value `fs` (filesystem) or `zip` (compressed file).
+ * @param {String} [tile.layout='dz'] filesystem layout, possible values are `dz`, `zoomify` or `google`.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function tile (tile) {
+  if (is.object(tile)) {
+    // Size of square tiles, in pixels
+    if (is.defined(tile.size)) {
+      if (is.integer(tile.size) && is.inRange(tile.size, 1, 8192)) {
+        this.options.tileSize = tile.size;
+      } else {
+        throw new Error('Invalid tile size (1 to 8192) ' + tile.size);
+      }
+    }
+    // Overlap of tiles, in pixels
+    if (is.defined(tile.overlap)) {
+      if (is.integer(tile.overlap) && is.inRange(tile.overlap, 0, 8192)) {
+        if (tile.overlap > this.options.tileSize) {
+          throw new Error('Tile overlap ' + tile.overlap + ' cannot be larger than tile size ' + this.options.tileSize);
+        }
+        this.options.tileOverlap = tile.overlap;
+      } else {
+        throw new Error('Invalid tile overlap (0 to 8192) ' + tile.overlap);
+      }
+    }
+    // Container
+    if (is.defined(tile.container)) {
+      if (is.string(tile.container) && is.inArray(tile.container, ['fs', 'zip'])) {
+        this.options.tileContainer = tile.container;
+      } else {
+        throw new Error('Invalid tile container ' + tile.container);
+      }
+    }
+    // Layout
+    if (is.defined(tile.layout)) {
+      if (is.string(tile.layout) && is.inArray(tile.layout, ['dz', 'google', 'zoomify'])) {
+        this.options.tileLayout = tile.layout;
+      } else {
+        throw new Error('Invalid tile layout ' + tile.layout);
+      }
+    }
+
+    // Angle of rotation,
+    if (is.defined(tile.angle)) {
+      if (is.integer(tile.angle) && !(tile.angle % 90)) {
+        this.options.tileAngle = tile.angle;
+      } else {
+        throw new Error('Unsupported angle: angle must be a positive/negative multiple of 90 ' + tile.angle);
+      }
+    }
+
+    // Depth of tiles
+    if (is.defined(tile.depth)) {
+      if (is.string(tile.depth) && is.inArray(tile.depth, ['onepixel', 'onetile', 'one'])) {
+        this.options.tileDepth = tile.depth;
+      } else {
+        throw new Error("Invalid tile depth '" + tile.depth + "', should be one of 'onepixel', 'onetile' or 'one'");
+      }
+    }
+  }
+  // Format
+  if (is.inArray(this.options.formatOut, ['jpeg', 'png', 'webp'])) {
+    this.options.tileFormat = this.options.formatOut;
+  } else if (this.options.formatOut !== 'input') {
+    throw new Error('Invalid tile format ' + this.options.formatOut);
+  }
+
+  return this._updateFormatOut('dz');
+}
+
+/**
+ * Update the output format unless options.force is false,
+ * in which case revert to input format.
+ * @private
+ * @param {String} formatOut
+ * @param {Object} [options]
+ * @param {Boolean} [options.force=true] - force output format, otherwise attempt to use input format
+ * @returns {Sharp}
+ */
+function _updateFormatOut (formatOut, options) {
+  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
+ */
+function _setBooleanOption (key, val) {
+  if (is.bool(val)) {
+    this.options[key] = val;
+  } else {
+    throw new Error('Invalid ' + key + ' (boolean) ' + val);
+  }
+}
+
+/**
+ * Called by a WriteableStream to notify us it is ready for data.
+ * @private
+ */
+function _read () {
+  if (!this.options.streamOut) {
+    this.options.streamOut = true;
+    this._pipeline();
+  }
+}
+
+/**
+ * Invoke the C++ image processing pipeline
+ * Supports callback, stream and promise variants
+ * @private
+ */
+function _pipeline (callback) {
+  const that = this;
+  if (typeof callback === 'function') {
+    // output=file/buffer
+    if (this._isStreamInput()) {
+      // output=file/buffer, input=stream
+      this.on('finish', function () {
+        that._flattenBufferIn();
+        sharp.pipeline(that.options, callback);
+      });
+    } else {
+      // output=file/buffer, input=file/buffer
+      sharp.pipeline(this.options, callback);
+    }
+    return this;
+  } else if (this.options.streamOut) {
+    // output=stream
+    if (this._isStreamInput()) {
+      // output=stream, input=stream
+      if (this.streamInFinished) {
+        this._flattenBufferIn();
+        sharp.pipeline(this.options, function (err, data, info) {
+          if (err) {
+            that.emit('error', err);
+          } else {
+            that.emit('info', info);
+            that.push(data);
+          }
+          that.push(null);
+        });
+      } else {
+        this.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.pipeline(that.options, function (err, data, info) {
+            if (err) {
+              that.emit('error', err);
+            } else {
+              that.emit('info', info);
+              that.push(data);
+            }
+            that.push(null);
+          });
+        });
+      }
+    } else {
+      // output=stream, input=file/buffer
+      sharp.pipeline(this.options, function (err, data, info) {
+        if (err) {
+          that.emit('error', err);
+        } else {
+          that.emit('info', info);
+          that.push(data);
+        }
+        that.push(null);
+      });
+    }
+    return this;
+  } else {
+    // output=promise
+    if (this._isStreamInput()) {
+      // output=promise, input=stream
+      return new Promise(function (resolve, reject) {
+        that.on('finish', function () {
+          that._flattenBufferIn();
+          sharp.pipeline(that.options, function (err, data, info) {
+            if (err) {
+              reject(err);
+            } else {
+              if (that.options.resolveWithObject) {
+                resolve({ data: data, info: info });
+              } else {
+                resolve(data);
+              }
+            }
+          });
+        });
+      });
+    } else {
+      // output=promise, input=file/buffer
+      return new Promise(function (resolve, reject) {
+        sharp.pipeline(that.options, function (err, data, info) {
+          if (err) {
+            reject(err);
+          } else {
+            if (that.options.resolveWithObject) {
+              resolve({ data: data, info: info });
+            } else {
+              resolve(data);
+            }
+          }
+        });
+      });
+    }
+  }
+}
+
+/**
+ * Decorate the Sharp prototype with output-related functions.
+ * @private
+ */
+module.exports = function (Sharp) {
+  [
+    // Public
+    toFile,
+    toBuffer,
+    withMetadata,
+    jpeg,
+    png,
+    webp,
+    tiff,
+    raw,
+    toFormat,
+    tile,
+    // Private
+    _updateFormatOut,
+    _setBooleanOption,
+    _read,
+    _pipeline
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+};

lib/platform.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const detectLibc = require('detect-libc');
+
+module.exports = function () {
+  const arch = process.env.npm_config_arch || process.arch;
+  const platform = process.env.npm_config_platform || process.platform;
+  const libc = (platform === 'linux' && detectLibc.isNonGlibcLinux) ? detectLibc.family : '';
+
+  const platformId = [`${platform}${libc}`];
+  if (arch === 'arm' || arch === 'armhf' || arch === 'arm64') {
+    const armVersion = (arch === 'arm64') ? '8' : process.env.npm_config_armv || process.config.variables.arm_version || '6';
+    platformId.push(`armv${armVersion}`);
+  } else {
+    platformId.push(arch);
+  }
+  return platformId.join('-');
+};

lib/resize.js

@@ -0,0 +1,492 @@
+'use strict';
+
+const deprecate = require('util').deprecate;
+const is = require('./is');
+
+/**
+ * Weighting to apply when using contain/cover fit.
+ * @member
+ * @private
+ */
+const gravity = {
+  center: 0,
+  centre: 0,
+  north: 1,
+  east: 2,
+  south: 3,
+  west: 4,
+  northeast: 5,
+  southeast: 6,
+  southwest: 7,
+  northwest: 8
+};
+
+/**
+ * Position to apply when using contain/cover fit.
+ * @member
+ * @private
+ */
+const position = {
+  top: 1,
+  right: 2,
+  bottom: 3,
+  left: 4,
+  'right top': 5,
+  'right bottom': 6,
+  'left bottom': 7,
+  'left top': 8
+};
+
+/**
+ * Strategies for automagic cover behaviour.
+ * @member
+ * @private
+ */
+const strategy = {
+  entropy: 16,
+  attention: 17
+};
+
+/**
+ * Reduction kernels.
+ * @member
+ * @private
+ */
+const kernel = {
+  nearest: 'nearest',
+  cubic: 'cubic',
+  lanczos2: 'lanczos2',
+  lanczos3: 'lanczos3'
+};
+
+/**
+ * Methods by which an image can be resized to fit the provided dimensions.
+ * @member
+ * @private
+ */
+const fit = {
+  contain: 'contain',
+  cover: 'cover',
+  fill: 'fill',
+  inside: 'inside',
+  outside: 'outside'
+};
+
+/**
+ * Map external fit property to internal canvas property.
+ * @member
+ * @private
+ */
+const mapFitToCanvas = {
+  contain: 'embed',
+  cover: 'crop',
+  fill: 'ignore_aspect',
+  inside: 'max',
+  outside: 'min'
+};
+
+/**
+ * Resize image to `width`, `height` or `width x height`.
+ *
+ * When both a `width` and `height` are provided, the possible methods by which the image should **fit** these are:
+ * - `cover`: Crop to cover both provided dimensions (the default).
+ * - `contain`: Embed within both provided dimensions.
+ * - `fill`: Ignore the aspect ratio of the input and stretch to both provided dimensions.
+ * - `inside`: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to both those specified.
+ * - `outside`: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to both those specified.
+ * Some of these values are based on the [object-fit](https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit) CSS property.
+ *
+ * When using a `fit` of `cover` or `contain`, the default **position** is `centre`. Other options are:
+ * - `sharp.position`: `top`, `right top`, `right`, `right bottom`, `bottom`, `left bottom`, `left`, `left top`.
+ * - `sharp.gravity`: `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` or `centre`.
+ * - `sharp.strategy`: `cover` only, dynamically crop using either the `entropy` or `attention` strategy.
+ * Some of these values are based on the [object-position](https://developer.mozilla.org/en-US/docs/Web/CSS/object-position) CSS property.
+ *
+ * The experimental strategy-based approach resizes so one dimension is at its target length
+ * then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.
+ * - `entropy`: focus on the region with the highest [Shannon entropy](https://en.wikipedia.org/wiki/Entropy_%28information_theory%29).
+ * - `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.
+ *
+ * Possible interpolation kernels are:
+ * - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
+ * - `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
+ * - `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
+ * - `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
+ *
+ * @example
+ * sharp(input)
+ *   .resize({ width: 100 })
+ *   .toBuffer()
+ *   .then(data => {
+ *     // 100 pixels wide, auto-scaled height
+ *   });
+ *
+ * @example
+ * sharp(input)
+ *   .resize({ height: 100 })
+ *   .toBuffer()
+ *   .then(data => {
+ *     // 100 pixels high, auto-scaled width
+ *   });
+ *
+ * @example
+ * sharp(input)
+ *   .resize(200, 300, {
+ *     kernel: sharp.kernel.nearest,
+ *     fit: 'contain',
+ *     position: 'right top',
+ *     background: { r: 255, g: 255, b: 255, alpha: 0.5 }
+ *   })
+ *   .toFile('output.png')
+ *   .then(() => {
+ *     // output.png is a 200 pixels wide and 300 pixels high image
+ *     // containing a nearest-neighbour scaled version
+ *     // contained within the north-east corner of a semi-transparent white canvas
+ *   });
+ *
+ * @example
+ * const transformer = sharp()
+ *   .resize({
+ *     width: 200,
+ *     height: 200,
+ *     fit: sharp.fit.cover,
+ *     position: sharp.strategy.entropy
+ *   });
+ * // Read image data from readableStream
+ * // Write 200px square auto-cropped image data to writableStream
+ * readableStream
+ *   .pipe(transformer)
+ *   .pipe(writableStream);
+ *
+ * @example
+ * sharp(input)
+ *   .resize(200, 200, {
+ *     fit: sharp.fit.inside,
+ *     withoutEnlargement: true
+ *   })
+ *   .toFormat('jpeg')
+ *   .toBuffer()
+ *   .then(function(outputBuffer) {
+ *     // outputBuffer contains JPEG image data
+ *     // no wider and no higher than 200 pixels
+ *     // and no larger than the input image
+ *   });
+ *
+ * @param {Number} [width] - pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
+ * @param {Number} [height] - pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
+ * @param {Object} [options]
+ * @param {String} [options.width] - alternative means of specifying `width`. If both are present this take priority.
+ * @param {String} [options.height] - alternative means of specifying `height`. If both are present this take priority.
+ * @param {String} [options.fit='cover'] - how the image should be resized to fit both provided dimensions, one of `cover`, `contain`, `fill`, `inside` or `outside`.
+ * @param {String} [options.position='centre'] - position, gravity or strategy to use when `fit` is `cover` or `contain`.
+ * @param {String|Object} [options.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour when using a `fit` of `contain`, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
+ * @param {String} [options.kernel='lanczos3'] - the kernel to use for image reduction.
+ * @param {Boolean} [options.withoutEnlargement=false] - do not enlarge if the width *or* height are already less than the specified dimensions, equivalent to GraphicsMagick's `>` geometry option.
+ * @param {Boolean} [options.fastShrinkOnLoad=true] - take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function resize (width, height, options) {
+  if (is.defined(width)) {
+    if (is.object(width) && !is.defined(options)) {
+      options = width;
+    } else if (is.integer(width) && width > 0) {
+      this.options.width = width;
+    } else {
+      throw is.invalidParameterError('width', 'positive integer', width);
+    }
+  } else {
+    this.options.width = -1;
+  }
+  if (is.defined(height)) {
+    if (is.integer(height) && height > 0) {
+      this.options.height = height;
+    } else {
+      throw is.invalidParameterError('height', 'positive integer', height);
+    }
+  } else {
+    this.options.height = -1;
+  }
+  if (is.object(options)) {
+    // Width
+    if (is.integer(options.width) && options.width > 0) {
+      this.options.width = options.width;
+    }
+    // Height
+    if (is.integer(options.height) && options.height > 0) {
+      this.options.height = options.height;
+    }
+    // Fit
+    if (is.defined(options.fit)) {
+      const canvas = mapFitToCanvas[options.fit];
+      if (is.string(canvas)) {
+        this.options.canvas = canvas;
+      } else {
+        throw is.invalidParameterError('fit', 'valid fit', options.fit);
+      }
+    }
+    // Position
+    if (is.defined(options.position)) {
+      const pos = is.integer(options.position)
+        ? options.position
+        : strategy[options.position] || position[options.position] || gravity[options.position];
+      if (is.integer(pos) && (is.inRange(pos, 0, 8) || is.inRange(pos, 16, 17))) {
+        this.options.position = pos;
+      } else {
+        throw is.invalidParameterError('position', 'valid position/gravity/strategy', options.position);
+      }
+    }
+    // Background
+    if (is.defined(options.background)) {
+      this._setColourOption('resizeBackground', options.background);
+    }
+    // Kernel
+    if (is.defined(options.kernel)) {
+      if (is.string(kernel[options.kernel])) {
+        this.options.kernel = kernel[options.kernel];
+      } else {
+        throw is.invalidParameterError('kernel', 'valid kernel name', options.kernel);
+      }
+    }
+    // Without enlargement
+    if (is.defined(options.withoutEnlargement)) {
+      this._setBooleanOption('withoutEnlargement', options.withoutEnlargement);
+    }
+    // Shrink on load
+    if (is.defined(options.fastShrinkOnLoad)) {
+      this._setBooleanOption('fastShrinkOnLoad', options.fastShrinkOnLoad);
+    }
+  }
+  return this;
+}
+
+/**
+ * Extends/pads the edges of the image with the provided background colour.
+ * This operation will always occur after resizing and extraction, if any.
+ *
+ * @example
+ * // Resize to 140 pixels wide, then add 10 transparent pixels
+ * // to the top, left and right edges and 20 to the bottom edge
+ * sharp(input)
+ *   .resize(140)
+ *   .)
+ *   .extend({
+ *     top: 10,
+ *     bottom: 20,
+ *     left: 10,
+ *     right: 10
+ *     background: { r: 0, g: 0, b: 0, alpha: 0 }
+ *   })
+ *   ...
+ *
+ * @param {(Number|Object)} extend - single pixel count to add to all edges or an Object with per-edge counts
+ * @param {Number} [extend.top]
+ * @param {Number} [extend.left]
+ * @param {Number} [extend.bottom]
+ * @param {Number} [extend.right]
+ * @param {String|Object} [extend.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+*/
+function extend (extend) {
+  if (is.integer(extend) && extend > 0) {
+    this.options.extendTop = extend;
+    this.options.extendBottom = extend;
+    this.options.extendLeft = extend;
+    this.options.extendRight = extend;
+  } else if (
+    is.object(extend) &&
+    is.integer(extend.top) && extend.top >= 0 &&
+    is.integer(extend.bottom) && extend.bottom >= 0 &&
+    is.integer(extend.left) && extend.left >= 0 &&
+    is.integer(extend.right) && extend.right >= 0
+  ) {
+    this.options.extendTop = extend.top;
+    this.options.extendBottom = extend.bottom;
+    this.options.extendLeft = extend.left;
+    this.options.extendRight = extend.right;
+    this._setColourOption('extendBackground', extend.background);
+  } else {
+    throw new Error('Invalid edge extension ' + extend);
+  }
+  return this;
+}
+
+/**
+ * Extract a region of the image.
+ *
+ * - Use `extract` before `resize` for pre-resize extraction.
+ * - Use `extract` after `resize` for post-resize extraction.
+ * - Use `extract` before and after for both.
+ *
+ * @example
+ * sharp(input)
+ *   .extract({ left: left, top: top, width: width, height: height })
+ *   .toFile(output, function(err) {
+ *     // Extract a region of the input image, saving in the same format.
+ *   });
+ * @example
+ * sharp(input)
+ *   .extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
+ *   .resize(width, height)
+ *   .extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
+ *   .toFile(output, function(err) {
+ *     // Extract a region, resize, then extract from the resized image
+ *   });
+ *
+ * @param {Object} options
+ * @param {Number} options.left - zero-indexed offset from left edge
+ * @param {Number} options.top - zero-indexed offset from top edge
+ * @param {Number} options.width - dimension of extracted image
+ * @param {Number} options.height - dimension of extracted image
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function extract (options) {
+  const suffix = this.options.width === -1 && this.options.height === -1 ? 'Pre' : 'Post';
+  ['left', 'top', 'width', 'height'].forEach(function (name) {
+    const value = options[name];
+    if (is.integer(value) && value >= 0) {
+      this.options[name + (name === 'left' || name === 'top' ? 'Offset' : '') + suffix] = value;
+    } else {
+      throw new Error('Non-integer value for ' + name + ' of ' + value);
+    }
+  }, this);
+  // Ensure existing rotation occurs before pre-resize extraction
+  if (suffix === 'Pre' && ((this.options.angle % 360) !== 0 || this.options.useExifOrientation === true)) {
+    this.options.rotateBeforePreExtract = true;
+  }
+  return this;
+}
+
+/**
+ * Trim "boring" pixels from all edges that contain values similar to the top-left pixel.
+ * The `info` response Object will contain `trimOffsetLeft` and `trimOffsetTop` properties.
+ * @param {Number} [threshold=10] the allowed difference from the top-left pixel, a number greater than zero.
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function trim (threshold) {
+  if (!is.defined(threshold)) {
+    this.options.trimThreshold = 10;
+  } else if (is.number(threshold) && threshold > 0) {
+    this.options.trimThreshold = threshold;
+  } else {
+    throw is.invalidParameterError('threshold', 'number greater than zero', threshold);
+  }
+  return this;
+}
+
+// Deprecated functions
+
+/**
+ * @deprecated
+ * @private
+ */
+function crop (crop) {
+  this.options.canvas = 'crop';
+  if (!is.defined(crop)) {
+    // Default
+    this.options.position = gravity.center;
+  } else if (is.integer(crop) && is.inRange(crop, 0, 8)) {
+    // Gravity (numeric)
+    this.options.position = crop;
+  } else if (is.string(crop) && is.integer(gravity[crop])) {
+    // Gravity (string)
+    this.options.position = gravity[crop];
+  } else if (is.integer(crop) && crop >= strategy.entropy) {
+    // Strategy
+    this.options.position = crop;
+  } else if (is.string(crop) && is.integer(strategy[crop])) {
+    // Strategy (string)
+    this.options.position = strategy[crop];
+  } else {
+    throw is.invalidParameterError('crop', 'valid crop id/name/strategy', crop);
+  }
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+ */
+function embed (embed) {
+  this.options.canvas = 'embed';
+  if (!is.defined(embed)) {
+    // Default
+    this.options.position = gravity.center;
+  } else if (is.integer(embed) && is.inRange(embed, 0, 8)) {
+    // Gravity (numeric)
+    this.options.position = embed;
+  } else if (is.string(embed) && is.integer(gravity[embed])) {
+    // Gravity (string)
+    this.options.position = gravity[embed];
+  } else {
+    throw is.invalidParameterError('embed', 'valid embed id/name', embed);
+  }
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+ */
+function max () {
+  this.options.canvas = 'max';
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+ */
+function min () {
+  this.options.canvas = 'min';
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+ */
+function ignoreAspectRatio () {
+  this.options.canvas = 'ignore_aspect';
+  return this;
+}
+
+/**
+ * @deprecated
+ * @private
+*/
+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,
+    extend,
+    extract,
+    trim
+  ].forEach(function (f) {
+    Sharp.prototype[f.name] = f;
+  });
+  // Class attributes
+  Sharp.gravity = gravity;
+  Sharp.strategy = strategy;
+  Sharp.kernel = kernel;
+  Sharp.fit = fit;
+  Sharp.position = position;
+  // Deprecated functions, to be removed in v0.22.0
+  Sharp.prototype.crop = deprecate(crop, 'crop(position) is deprecated, use resize({ fit: "cover", position }) instead');
+  Sharp.prototype.embed = deprecate(embed, 'embed(position) is deprecated, use resize({ fit: "contain", position }) instead');
+  Sharp.prototype.max = deprecate(max, 'max() is deprecated, use resize({ fit: "inside" }) instead');
+  Sharp.prototype.min = deprecate(min, 'min() is deprecated, use resize({ fit: "outside" }) instead');
+  Sharp.prototype.ignoreAspectRatio = deprecate(ignoreAspectRatio, 'ignoreAspectRatio() is deprecated, use resize({ fit: "fill" }) instead');
+  Sharp.prototype.withoutEnlargement = deprecate(withoutEnlargement, 'withoutEnlargement() is deprecated, use resize({ withoutEnlargement: true }) instead');
+};

lib/utility.js

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

mkdocs.yml

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

package.json

@@ -1,32 +1,137 @@
 {
   "name": "sharp",
-  "version": "0.0.2",
-  "main": "index.js",
-  "description": "High performance Node.js module to resize JPEG images using the libvips image processing library",
+  "description": "High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP and TIFF images",
+  "version": "0.21.0",
+  "author": "Lovell Fuller <npm@lovell.info>",
+  "homepage": "https://github.com/lovell/sharp",
+  "contributors": [
+    "Pierre Inglebert <pierre.inglebert@gmail.com>",
+    "Jonathan Ong <jonathanrichardong@gmail.com>",
+    "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>",
+    "Rahul Nanwani <r.nanwani@gmail.com>",
+    "Alice Monday <alice0meta@gmail.com>",
+    "Kristo Jorgenson <kristo.jorgenson@gmail.com>",
+    "YvesBos <yves_bos@outlook.com>",
+    "Guy Maliar <guy@tailorbrands.com>",
+    "Nicolas Coden <nicolas@ncoden.fr>",
+    "Matt Parrish <matt.r.parrish@gmail.com>",
+    "Marcel Bretschneider <marcel.bretschneider@gmail.com>",
+    "Matthew McEachen <matthew+github@mceachen.org>",
+    "Jarda Kotěšovec <jarda.kotesovec@gmail.com>",
+    "Kenric D'Souza <kenric.dsouza@gmail.com>",
+    "Oleh Aleinyk <oleg.aleynik@gmail.com>",
+    "Marcel Bretschneider <marcel.bretschneider@gmail.com>",
+    "Andrea Bianco <andrea.bianco@unibas.ch>",
+    "Rik Heywood <rik@rik.org>",
+    "Thomas Parisot <hi@oncletom.io>",
+    "Nathan Graves <nathanrgraves+github@gmail.com>",
+    "Tom Lokhorst <tom@lokhorst.eu>",
+    "Espen Hovlandsdal <espen@hovlandsdal.com>",
+    "Sylvain Dumont <sylvain.dumont35@gmail.com>",
+    "Alun Davies <alun.owain.davies@googlemail.com>",
+    "Aidan Hoolachan <ajhoolachan21@gmail.com>",
+    "Axel Eirola <axel.eirola@iki.fi>",
+    "Freezy <freezy@xbmc.org>"
+  ],
+  "scripts": {
+    "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node-gyp rebuild && node install/dll-copy)",
+    "clean": "rm -rf node_modules/ build/ vendor/ .nyc_output/ coverage/ test/fixtures/output.*",
+    "test": "semistandard && cc && nyc --reporter=lcov --branches=99 mocha --slow=5000 --timeout=60000 ./test/unit/*.js && prebuild-ci",
+    "coverage": "./test/coverage/report.sh",
+    "test-leak": "./test/leak/leak.sh",
+    "docs": "for m in constructor input resize composite operation colour channel output utility; do documentation build --shallow --format=md --markdown-toc=false lib/$m.js >docs/api-$m.md; done"
+  },
+  "main": "lib/index.js",
   "repository": {
     "type": "git",
     "url": "git://github.com/lovell/sharp"
   },
-  "devDependencies": {
-    "imagemagick": "*",
-    "benchmark": "*"
-  },
-  "scripts": {
-    "test": "node tests/perf.js"
-  },
-  "engines": {
-    "node": "*"
-  },
   "keywords": [
     "jpeg",
+    "png",
+    "webp",
+    "tiff",
+    "gif",
+    "svg",
+    "dzi",
+    "image",
     "resize",
     "thumbnail",
-    "sharpen",
     "crop",
     "embed",
     "libvips",
-    "fast"
+    "vips"
   ],
-  "author": "Lovell Fuller",
-  "license": "Apache 2.0"
-}
+  "dependencies": {
+    "color": "^3.0.0",
+    "detect-libc": "^1.0.3",
+    "nan": "^2.11.1",
+    "fs-copy-file-sync": "^1.1.1",
+    "npmlog": "^4.1.2",
+    "prebuild-install": "^5.2.0",
+    "semver": "^5.5.1",
+    "simple-get": "^3.0.3",
+    "tar": "^4.4.6",
+    "tunnel-agent": "^0.6.0"
+  },
+  "devDependencies": {
+    "async": "^2.6.1",
+    "cc": "^1.0.2",
+    "decompress-zip": "^0.3.1",
+    "documentation": "^8.1.2",
+    "exif-reader": "^1.0.2",
+    "icc": "^1.0.0",
+    "mocha": "^5.2.0",
+    "mock-fs": "^4.7.0",
+    "nyc": "^13.1.0",
+    "prebuild": "^8.1.0",
+    "prebuild-ci": "^2.2.3",
+    "rimraf": "^2.6.2",
+    "semistandard": "^12.0.1"
+  },
+  "license": "Apache-2.0",
+  "config": {
+    "libvips": "8.7.0"
+  },
+  "engines": {
+    "node": ">=6"
+  },
+  "semistandard": {
+    "env": [
+      "mocha"
+    ]
+  },
+  "cc": {
+    "linelength": "120",
+    "filter": [
+      "build/c++11",
+      "build/include",
+      "runtime/indentation_namespace",
+      "runtime/references"
+    ]
+  }
+}

src/common.cc

@@ -0,0 +1,646 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cstdlib>
+#include <string>
+#include <string.h>
+#include <vector>
+#include <queue>
+#include <mutex>
+
+#include <node.h>
+#include <node_buffer.h>
+#include <nan.h>
+#include <vips/vips8>
+
+#include "common.h"
+
+using vips::VImage;
+
+namespace sharp {
+
+  // Convenience methods to access the attributes of a v8::Object
+  bool HasAttr(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::Has(obj, Nan::New(attr).ToLocalChecked()).FromJust();
+  }
+  std::string AttrAsStr(v8::Handle<v8::Object> obj, std::string attr) {
+    return *Nan::Utf8String(Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked());
+  }
+  std::vector<double> AttrAsRgba(v8::Handle<v8::Object> obj, std::string attr) {
+    v8::Local<v8::Object> background = AttrAs<v8::Object>(obj, attr);
+    std::vector<double> rgba(4);
+    for (unsigned int i = 0; i < 4; i++) {
+      rgba[i] = AttrTo<double>(background, i);
+    }
+    return rgba;
+  }
+
+  // Create an InputDescriptor instance from a v8::Object describing an input image
+  InputDescriptor* CreateInputDescriptor(
+    v8::Handle<v8::Object> input, std::vector<v8::Local<v8::Object>> &buffersToPersist
+  ) {
+    Nan::HandleScope();
+    InputDescriptor *descriptor = new InputDescriptor;
+    if (HasAttr(input, "file")) {
+      descriptor->file = AttrAsStr(input, "file");
+    } else if (HasAttr(input, "buffer")) {
+      v8::Local<v8::Object> buffer = AttrAs<v8::Object>(input, "buffer");
+      descriptor->bufferLength = node::Buffer::Length(buffer);
+      descriptor->buffer = node::Buffer::Data(buffer);
+      buffersToPersist.push_back(buffer);
+    }
+    descriptor->failOnError = AttrTo<bool>(input, "failOnError");
+    // Density for vector-based input
+    if (HasAttr(input, "density")) {
+      descriptor->density = AttrTo<double>(input, "density");
+    }
+    // Raw pixel input
+    if (HasAttr(input, "rawChannels")) {
+      descriptor->rawChannels = AttrTo<uint32_t>(input, "rawChannels");
+      descriptor->rawWidth = AttrTo<uint32_t>(input, "rawWidth");
+      descriptor->rawHeight = AttrTo<uint32_t>(input, "rawHeight");
+    }
+    // Page input for multi-page TIFF
+    if (HasAttr(input, "page")) {
+      descriptor->page = AttrTo<uint32_t>(input, "page");
+    }
+    // Create new image
+    if (HasAttr(input, "createChannels")) {
+      descriptor->createChannels = AttrTo<uint32_t>(input, "createChannels");
+      descriptor->createWidth = AttrTo<uint32_t>(input, "createWidth");
+      descriptor->createHeight = AttrTo<uint32_t>(input, "createHeight");
+      descriptor->createBackground = AttrAsRgba(input, "createBackground");
+    }
+    return descriptor;
+  }
+
+  // How many tasks are in the queue?
+  volatile int counterQueue = 0;
+
+  // 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) {
+      if (descriptor->rawChannels > 0) {
+        // Raw, uncompressed pixel data
+        image = VImage::new_from_memory(descriptor->buffer, descriptor->bufferLength,
+          descriptor->rawWidth, descriptor->rawHeight, descriptor->rawChannels, VIPS_FORMAT_UCHAR);
+        if (descriptor->rawChannels < 3) {
+          image.get_image()->Type = VIPS_INTERPRETATION_B_W;
+        } else {
+          image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
+        }
+        imageType = ImageType::RAW;
+      } else {
+        // Compressed data
+        imageType = DetermineImageType(descriptor->buffer, descriptor->bufferLength);
+        if (imageType != ImageType::UNKNOWN) {
+          try {
+            vips::VOption *option = VImage::option()
+              ->set("access", accessMethod)
+              ->set("fail", descriptor->failOnError);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+              option->set("dpi", descriptor->density);
+            }
+            if (imageType == ImageType::MAGICK) {
+              option->set("density", std::to_string(descriptor->density).data());
+            }
+            if (imageType == ImageType::TIFF) {
+             option->set("page", descriptor->page);
+            }
+            image = VImage::new_from_buffer(descriptor->buffer, descriptor->bufferLength, nullptr, option);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
+              SetDensity(image, descriptor->density);
+            }
+          } catch (...) {
+            throw vips::VError("Input buffer has corrupt header");
+          }
+        } else {
+          throw vips::VError("Input buffer contains unsupported image format");
+        }
+      }
+    } else {
+      if (descriptor->createChannels > 0) {
+        // Create new image
+        std::vector<double> background = {
+          descriptor->createBackground[0],
+          descriptor->createBackground[1],
+          descriptor->createBackground[2]
+        };
+        if (descriptor->createChannels == 4) {
+          background.push_back(descriptor->createBackground[3]);
+        }
+        image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight).new_from_image(background);
+        image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
+        imageType = ImageType::RAW;
+      } else {
+        // From filesystem
+        imageType = DetermineImageType(descriptor->file.data());
+        if (imageType != ImageType::UNKNOWN) {
+          try {
+            vips::VOption *option = VImage::option()
+              ->set("access", accessMethod)
+              ->set("fail", descriptor->failOnError);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF) {
+              option->set("dpi", descriptor->density);
+            }
+            if (imageType == ImageType::MAGICK) {
+              option->set("density", std::to_string(descriptor->density).data());
+            }
+            if (imageType == ImageType::TIFF) {
+             option->set("page", descriptor->page);
+            }
+            image = VImage::new_from_file(descriptor->file.data(), option);
+            if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
+              SetDensity(image, descriptor->density);
+            }
+          } catch (...) {
+            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 double density) {
+    const double pixelsPerMm = density / 25.4;
+    image.set("Xres", pixelsPerMm);
+    image.set("Yres", pixelsPerMm);
+    image.set(VIPS_META_RESOLUTION_UNIT, "in");
+  }
+
+  /*
+    Check the proposed format supports the current dimensions.
+  */
+  void AssertImageTypeDimensions(VImage image, ImageType const imageType) {
+    if (imageType == ImageType::JPEG) {
+      if (image.width() > 65535 || image.height() > 65535) {
+        throw vips::VError("Processed image is too large for the JPEG format");
+      }
+    } else if (imageType == ImageType::WEBP) {
+      if (image.width() > 16383 || image.height() > 16383) {
+        throw vips::VError("Processed image is too large for the WebP format");
+      }
+    }
+  }
+
+  /*
+    Called when a Buffer undergoes GC, required to support mixed runtime libraries in Windows
+  */
+  void FreeCallback(char* data, void* hint) {
+    if (data != nullptr) {
+      g_free(data);
+    }
+  }
+
+  /*
+    Temporary buffer of warnings
+  */
+  std::queue<std::string> vipsWarnings;
+  std::mutex vipsWarningsMutex;
+
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore) {
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    vipsWarnings.emplace(message);
+  }
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop() {
+    std::string warning;
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    if (!vipsWarnings.empty()) {
+      warning = vipsWarnings.front();
+      vipsWarnings.pop();
+    }
+    return warning;
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during an embed.
+
+    @Azurebyte: We are basically swapping the inWidth and outWidth, inHeight and outHeight from the CalculateCrop function.
+  */
+  std::tuple<int, int> CalculateEmbedPosition(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity) {
+
+    int left = 0;
+    int top = 0;
+    switch (gravity) {
+      case 1:
+        // North
+        left = (outWidth - inWidth) / 2;
+        break;
+      case 2:
+        // East
+        left = outWidth - inWidth;
+        top = (outHeight - inHeight) / 2;
+        break;
+      case 3:
+        // South
+        left = (outWidth - inWidth) / 2;
+        top = outHeight - inHeight;
+        break;
+      case 4:
+        // West
+        top = (outHeight - inHeight) / 2;
+        break;
+      case 5:
+        // Northeast
+        left = outWidth - inWidth;
+        break;
+      case 6:
+        // Southeast
+        left = outWidth - inWidth;
+        top = outHeight - inHeight;
+        break;
+      case 7:
+        // Southwest
+        top = outHeight - inHeight;
+        break;
+      case 8:
+        // Northwest
+        // Which is the default is 0,0 so we do not assign anything here.
+        break;
+      default:
+        // Centre
+        left = (outWidth - inWidth) / 2;
+        top = (outHeight - inHeight) / 2;
+    }
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during a crop.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity) {
+
+    int left = 0;
+    int top = 0;
+    switch (gravity) {
+      case 1:
+        // North
+        left = (inWidth - outWidth + 1) / 2;
+        break;
+      case 2:
+        // East
+        left = inWidth - outWidth;
+        top = (inHeight - outHeight + 1) / 2;
+        break;
+      case 3:
+        // South
+        left = (inWidth - outWidth + 1) / 2;
+        top = inHeight - outHeight;
+        break;
+      case 4:
+        // West
+        top = (inHeight - outHeight + 1) / 2;
+        break;
+      case 5:
+        // Northeast
+        left = inWidth - outWidth;
+        break;
+      case 6:
+        // Southeast
+        left = inWidth - outWidth;
+        top = inHeight - outHeight;
+        break;
+      case 7:
+        // Southwest
+        top = inHeight - outHeight;
+        break;
+      case 8:
+        // Northwest
+        break;
+      default:
+        // Centre
+        left = (inWidth - outWidth + 1) / 2;
+        top = (inHeight - outHeight + 1) / 2;
+    }
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given x and y offsets.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const x, int const y) {
+
+    // default values
+    int left = 0;
+    int top = 0;
+
+    // assign only if valid
+    if (x >= 0 && x < (inWidth - outWidth)) {
+      left = x;
+    } else if (x >= (inWidth - outWidth)) {
+      left = inWidth - outWidth;
+    }
+
+    if (y >= 0 && y < (inHeight - outHeight)) {
+      top = y;
+    } else if (y >= (inHeight - outHeight)) {
+      top = inHeight - outHeight;
+    }
+
+    // the resulting left and top could have been outside the image after calculation from bottom/right edges
+    if (left < 0) {
+      left = 0;
+    }
+    if (top < 0) {
+      top = 0;
+    }
+
+    return std::make_tuple(left, top);
+  }
+
+  /*
+    Are pixel values in this image 16-bit integer?
+  */
+  bool Is16Bit(VipsInterpretation const interpretation) {
+    return interpretation == VIPS_INTERPRETATION_RGB16 || interpretation == VIPS_INTERPRETATION_GREY16;
+  }
+
+  /*
+    Return the image alpha maximum. Useful for combining alpha bands. scRGB
+    images are 0 - 1 for image data, but the alpha is 0 - 255.
+  */
+  double MaximumImageAlpha(VipsInterpretation const interpretation) {
+    return Is16Bit(interpretation) ? 65535.0 : 255.0;
+  }
+
+  /*
+    Get boolean operation type from string
+  */
+  VipsOperationBoolean GetBooleanOperation(std::string const opStr) {
+    return static_cast<VipsOperationBoolean>(
+      vips_enum_from_nick(nullptr, VIPS_TYPE_OPERATION_BOOLEAN, opStr.data()));
+  }
+
+  /*
+    Get interpretation type from string
+  */
+  VipsInterpretation GetInterpretation(std::string const typeStr) {
+    return static_cast<VipsInterpretation>(
+      vips_enum_from_nick(nullptr, VIPS_TYPE_INTERPRETATION, typeStr.data()));
+  }
+
+  /*
+    Convert RGBA value to another colourspace
+  */
+  std::vector<double> GetRgbaAsColourspace(std::vector<double> const rgba, VipsInterpretation const interpretation) {
+    int const bands = static_cast<int>(rgba.size());
+    if (bands < 3 || interpretation == VIPS_INTERPRETATION_sRGB || interpretation == VIPS_INTERPRETATION_RGB) {
+      return rgba;
+    } else {
+      VImage pixel = VImage::new_matrix(1, 1);
+      pixel.set("bands", bands);
+      pixel = pixel.new_from_image(rgba);
+      pixel = pixel.colourspace(interpretation, VImage::option()->set("source_space", VIPS_INTERPRETATION_sRGB));
+      return pixel(0, 0);
+    }
+  }
+
+  /*
+    Apply the alpha channel to a given colour
+  */
+  std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, std::vector<double> colour) {
+    // Scale up 8-bit values to match 16-bit input image
+    double const multiplier = sharp::Is16Bit(image.interpretation()) ? 256.0 : 1.0;
+    // Create alphaColour colour
+    std::vector<double> alphaColour;
+    if (image.bands() > 2) {
+      alphaColour = {
+        multiplier * colour[0],
+        multiplier * colour[1],
+        multiplier * colour[2]
+      };
+    } else {
+      // Convert sRGB to greyscale
+      alphaColour = { multiplier * (
+        0.2126 * colour[0] +
+        0.7152 * colour[1] +
+        0.0722 * colour[2])
+      };
+    }
+    // Add alpha channel to alphaColour colour
+    if (colour[3] < 255.0 || HasAlpha(image)) {
+      alphaColour.push_back(colour[3] * multiplier);
+    }
+    // Ensure alphaColour colour uses correct colourspace
+    alphaColour = sharp::GetRgbaAsColourspace(alphaColour, image.interpretation());
+    // Add non-transparent alpha channel, if required
+    if (colour[3] < 255.0 && !HasAlpha(image)) {
+      image = image.bandjoin(
+        VImage::new_matrix(image.width(), image.height()).new_from_image(255 * multiplier));
+    }
+    return std::make_tuple(image, alphaColour);
+  }
+
+}  // namespace sharp

src/common.h

@@ -0,0 +1,262 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_COMMON_H_
+#define SRC_COMMON_H_
+
+#include <string>
+#include <tuple>
+#include <vector>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+
+// Verify platform and compiler compatibility
+
+#if (VIPS_MAJOR_VERSION < 8 || (VIPS_MAJOR_VERSION == 8 && VIPS_MINOR_VERSION < 6))
+#error libvips version 8.6.1+ is required - see sharp.pixelplumbing.com/page/install
+#endif
+
+#if ((!defined(__clang__)) && defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)))
+#error GCC version 4.6+ is required for C++11 features - see sharp.pixelplumbing.com/page/install#prerequisites
+#endif
+
+#if (defined(__clang__) && defined(__has_feature))
+#if (!__has_feature(cxx_range_for))
+#error clang version 3.0+ is required for C++11 features - see sharp.pixelplumbing.com/page/install#prerequisites
+#endif
+#endif
+
+using vips::VImage;
+
+namespace sharp {
+
+  struct InputDescriptor {
+    std::string name;
+    std::string file;
+    char *buffer;
+    bool failOnError;
+    size_t bufferLength;
+    double density;
+    int rawChannels;
+    int rawWidth;
+    int rawHeight;
+    int page;
+    int createChannels;
+    int createWidth;
+    int createHeight;
+    std::vector<double> createBackground;
+
+    InputDescriptor():
+      buffer(nullptr),
+      failOnError(FALSE),
+      bufferLength(0),
+      density(72.0),
+      rawChannels(0),
+      rawWidth(0),
+      rawHeight(0),
+      page(0),
+      createChannels(0),
+      createWidth(0),
+      createHeight(0),
+      createBackground{ 0.0, 0.0, 0.0, 255.0 } {}
+  };
+
+  // Convenience methods to access the attributes of a v8::Object
+  bool HasAttr(v8::Handle<v8::Object> obj, std::string attr);
+  std::string AttrAsStr(v8::Handle<v8::Object> obj, std::string attr);
+  std::vector<double> AttrAsRgba(v8::Handle<v8::Object> obj, std::string attr);
+  template<typename T> v8::Local<T> AttrAs(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked().As<T>();
+  }
+  template<typename T> T AttrTo(v8::Handle<v8::Object> obj, std::string attr) {
+    return Nan::To<T>(Nan::Get(obj, Nan::New(attr).ToLocalChecked()).ToLocalChecked()).FromJust();
+  }
+  template<typename T> T AttrTo(v8::Handle<v8::Object> obj, int attr) {
+    return Nan::To<T>(Nan::Get(obj, attr).ToLocalChecked()).FromJust();
+  }
+
+  // Create an InputDescriptor instance from a v8::Object describing an input image
+  InputDescriptor* CreateInputDescriptor(
+    v8::Handle<v8::Object> input, std::vector<v8::Local<v8::Object>> &buffersToPersist);
+
+  enum class ImageType {
+    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 double density);
+
+  /*
+    Check the proposed format supports the current dimensions.
+  */
+  void AssertImageTypeDimensions(VImage image, ImageType const imageType);
+
+  /*
+    Called when a Buffer undergoes GC, required to support mixed runtime libraries in Windows
+  */
+  void FreeCallback(char* data, void* hint);
+
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore);
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop();
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity during an embed.
+  */
+  std::tuple<int, int> CalculateEmbedPosition(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity);
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given gravity.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const gravity);
+
+  /*
+    Calculate the (left, top) coordinates of the output image
+    within the input image, applying the given x and y offsets of the output image.
+  */
+  std::tuple<int, int> CalculateCrop(int const inWidth, int const inHeight,
+    int const outWidth, int const outHeight, int const x, int const y);
+
+  /*
+    Are pixel values in this image 16-bit integer?
+  */
+  bool Is16Bit(VipsInterpretation const interpretation);
+
+  /*
+    Return the image alpha maximum. Useful for combining alpha bands. scRGB
+    images are 0 - 1 for image data, but the alpha is 0 - 255.
+  */
+  double MaximumImageAlpha(VipsInterpretation const interpretation);
+
+  /*
+    Get boolean operation type from string
+  */
+  VipsOperationBoolean GetBooleanOperation(std::string const opStr);
+
+  /*
+    Get interpretation type from string
+  */
+  VipsInterpretation GetInterpretation(std::string const typeStr);
+
+  /*
+    Convert RGBA value to another colourspace
+  */
+  std::vector<double> GetRgbaAsColourspace(std::vector<double> const rgba, VipsInterpretation const interpretation);
+
+  /*
+    Apply the alpha channel to a given colour
+   */
+  std::tuple<VImage, std::vector<double>> ApplyAlpha(VImage image, std::vector<double> colour);
+
+}  // namespace sharp
+
+#endif  // SRC_COMMON_H_

src/libvips/cplusplus/VError.cpp

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

src/libvips/cplusplus/VInterpolate.cpp

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

src/metadata.cc

@@ -0,0 +1,221 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <numeric>
+#include <vector>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+
+#include "common.h"
+#include "metadata.h"
+
+class MetadataWorker : public Nan::AsyncWorker {
+ public:
+  MetadataWorker(
+    Nan::Callback *callback, MetadataBaton *baton, Nan::Callback *debuglog,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist) :
+    Nan::AsyncWorker(callback, "sharp:MetadataWorker"),
+    baton(baton), debuglog(debuglog),
+    buffersToPersist(buffersToPersist) {
+    // Protect Buffer objects from GC, keyed on index
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        SaveToPersistent(index, buffer);
+        return index + 1;
+      });
+  }
+  ~MetadataWorker() {}
+
+  void Execute() {
+    // Decrement queued task counter
+    g_atomic_int_dec_and_test(&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();
+      baton->depth = vips_enum_nick(VIPS_TYPE_BAND_FORMAT, image.format());
+      if (sharp::HasDensity(image)) {
+        baton->density = sharp::GetDensity(image);
+      }
+      if (image.get_typeof("jpeg-chroma-subsample") == VIPS_TYPE_REF_STRING) {
+        baton->chromaSubsampling = image.get_string("jpeg-chroma-subsample");
+      }
+      if (image.get_typeof("interlaced") == G_TYPE_INT) {
+        baton->isProgressive = image.get_int("interlaced") == 1;
+      }
+      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;
+      }
+      // IPTC
+      if (image.get_typeof(VIPS_META_IPTC_NAME) == VIPS_TYPE_BLOB) {
+        size_t iptcLength;
+        void const *iptc = image.get_blob(VIPS_META_IPTC_NAME, &iptcLength);
+        baton->iptc = static_cast<char *>(g_malloc(iptcLength));
+        memcpy(baton->iptc, iptc, iptcLength);
+        baton->iptcLength = iptcLength;
+      }
+      // XMP
+      if (image.get_typeof(VIPS_META_XMP_NAME) == VIPS_TYPE_BLOB) {
+        size_t xmpLength;
+        void const *xmp = image.get_blob(VIPS_META_XMP_NAME, &xmpLength);
+        baton->xmp = static_cast<char *>(g_malloc(xmpLength));
+        memcpy(baton->xmp, xmp, xmpLength);
+        baton->xmpLength = xmpLength;
+      }
+    }
+
+    // Clean up
+    vips_error_clear();
+    vips_thread_shutdown();
+  }
+
+  void HandleOKCallback() {
+    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());
+      if (baton->input->bufferLength > 0) {
+        Set(info, New("size").ToLocalChecked(), New<v8::Uint32>(static_cast<uint32_t>(baton->input->bufferLength)));
+      }
+      Set(info, New("width").ToLocalChecked(), New<v8::Uint32>(baton->width));
+      Set(info, New("height").ToLocalChecked(), New<v8::Uint32>(baton->height));
+      Set(info, New("space").ToLocalChecked(), New<v8::String>(baton->space).ToLocalChecked());
+      Set(info, New("channels").ToLocalChecked(), New<v8::Uint32>(baton->channels));
+      Set(info, New("depth").ToLocalChecked(), New<v8::String>(baton->depth).ToLocalChecked());
+      if (baton->density > 0) {
+        Set(info, New("density").ToLocalChecked(), New<v8::Uint32>(baton->density));
+      }
+      if (!baton->chromaSubsampling.empty()) {
+        Set(info,
+          New("chromaSubsampling").ToLocalChecked(),
+          New<v8::String>(baton->chromaSubsampling).ToLocalChecked());
+      }
+      Set(info, New("isProgressive").ToLocalChecked(), New<v8::Boolean>(baton->isProgressive));
+      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());
+      }
+      if (baton->iptcLength > 0) {
+        Set(info,
+          New("iptc").ToLocalChecked(),
+          Nan::NewBuffer(baton->iptc, baton->iptcLength, sharp::FreeCallback, nullptr).ToLocalChecked());
+      }
+      if (baton->xmpLength > 0) {
+        Set(info,
+          New("xmp").ToLocalChecked(),
+          Nan::NewBuffer(baton->xmp, baton->xmpLength, sharp::FreeCallback, nullptr).ToLocalChecked());
+      }
+      argv[1] = info;
+    }
+
+    // Dispose of Persistent wrapper around input Buffers so they can be garbage collected
+    std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
+      [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
+        GetFromPersistent(index);
+        return index + 1;
+      });
+    delete baton->input;
+    delete baton;
+
+    // Handle warnings
+    std::string warning = sharp::VipsWarningPop();
+    while (!warning.empty()) {
+      v8::Local<v8::Value> message[1] = { New(warning).ToLocalChecked() };
+      debuglog->Call(1, message, async_resource);
+      warning = sharp::VipsWarningPop();
+    }
+
+    // Return to JavaScript
+    callback->Call(2, argv, async_resource);
+  }
+
+ private:
+  MetadataBaton* baton;
+  Nan::Callback *debuglog;
+  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);
+
+  // Function to notify of libvips warnings
+  Nan::Callback *debuglog = new Nan::Callback(sharp::AttrAs<v8::Function>(options, "debuglog"));
+
+  // Join queue for worker thread
+  Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
+  Nan::AsyncQueueWorker(new MetadataWorker(callback, baton, debuglog, buffersToPersist));
+
+  // Increment queued task counter
+  g_atomic_int_inc(&sharp::counterQueue);
+}

src/metadata.h

@@ -0,0 +1,71 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_METADATA_H_
+#define SRC_METADATA_H_
+
+#include <string>
+#include <nan.h>
+
+#include "./common.h"
+
+struct MetadataBaton {
+  // Input
+  sharp::InputDescriptor *input;
+  // Output
+  std::string format;
+  int width;
+  int height;
+  std::string space;
+  int channels;
+  std::string depth;
+  int density;
+  std::string chromaSubsampling;
+  bool isProgressive;
+  bool hasProfile;
+  bool hasAlpha;
+  int orientation;
+  char *exif;
+  size_t exifLength;
+  char *icc;
+  size_t iccLength;
+  char *iptc;
+  size_t iptcLength;
+  char *xmp;
+  size_t xmpLength;
+  std::string err;
+
+  MetadataBaton():
+    input(nullptr),
+    width(0),
+    height(0),
+    channels(0),
+    density(0),
+    isProgressive(false),
+    hasProfile(false),
+    hasAlpha(false),
+    orientation(0),
+    exif(nullptr),
+    exifLength(0),
+    icc(nullptr),
+    iccLength(0),
+    iptc(nullptr),
+    iptcLength(0),
+    xmp(nullptr),
+    xmpLength(0) {}
+};
+
+NAN_METHOD(metadata);
+
+#endif  // SRC_METADATA_H_

src/operations.cc

@@ -0,0 +1,358 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vector>
+
+#include <vips/vips8>
+
+#include "common.h"
+#include "operations.h"
+
+using vips::VImage;
+using vips::VError;
+
+namespace sharp {
+
+  /*
+    Removes alpha channel, if any.
+  */
+  VImage RemoveAlpha(VImage image) {
+    if (HasAlpha(image)) {
+      image = image.extract_band(0, VImage::option()->set("n", image.bands() - 1));
+    }
+    return image;
+  }
+
+  /*
+    Composite overlayImage over image at given position
+    Assumes alpha channels are already premultiplied and will be unpremultiplied after
+   */
+  VImage Composite(VImage image, VImage overlayImage, int const left, int const top) {
+    if (HasAlpha(overlayImage)) {
+      // Alpha composite
+      if (overlayImage.width() < image.width() || overlayImage.height() < image.height()) {
+        // Enlarge overlay
+        std::vector<double> const background { 0.0, 0.0, 0.0, 0.0 };
+        overlayImage = overlayImage.embed(left, top, image.width(), image.height(), VImage::option()
+          ->set("extend", VIPS_EXTEND_BACKGROUND)
+          ->set("background", background));
+      }
+      return AlphaComposite(image, overlayImage);
+    } else {
+      if (HasAlpha(image)) {
+        // Add alpha channel to overlayImage so channels match
+        double const multiplier = sharp::Is16Bit(overlayImage.interpretation()) ? 256.0 : 1.0;
+        overlayImage = overlayImage.bandjoin(
+          VImage::new_matrix(overlayImage.width(), overlayImage.height()).new_from_image(255 * multiplier));
+      }
+      return image.insert(overlayImage, left, top);
+    }
+  }
+
+  VImage AlphaComposite(VImage dst, VImage src) {
+    // 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/libvips/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()));
+  }
+
+  /*
+   * Tint an image using the specified chroma, preserving the original image luminance
+   */
+  VImage Tint(VImage image, double const a, double const b) {
+    // Get original colourspace
+    VipsInterpretation typeBeforeTint = image.interpretation();
+    if (typeBeforeTint == VIPS_INTERPRETATION_RGB) {
+      typeBeforeTint = VIPS_INTERPRETATION_sRGB;
+    }
+    // Extract luminance
+    VImage luminance = image.colourspace(VIPS_INTERPRETATION_LAB)[0];
+    // Create the tinted version by combining the L from the original and the chroma from the tint
+    std::vector<double> chroma {a, b};
+    VImage tinted = luminance
+      .bandjoin(chroma)
+      .copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_LAB))
+      .colourspace(typeBeforeTint);
+    // Attach original alpha channel, if any
+    if (HasAlpha(image)) {
+      // Extract original alpha channel
+      VImage alpha = image[image.bands() - 1];
+      // Join alpha channel to normalised image
+      tinted = tinted.bandjoin(alpha);
+    }
+    return tinted;
+  }
+
+  /*
+   * Stretch luminance to cover full dynamic range.
+   */
+  VImage Normalise(VImage image) {
+    // Get original colourspace
+    VipsInterpretation typeBeforeNormalize = image.interpretation();
+    if (typeBeforeNormalize == VIPS_INTERPRETATION_RGB) {
+      typeBeforeNormalize = VIPS_INTERPRETATION_sRGB;
+    }
+    // Convert to LAB colourspace
+    VImage lab = image.colourspace(VIPS_INTERPRETATION_LAB);
+    // Extract luminance
+    VImage luminance = lab[0];
+    // Find luminance range
+    VImage stats = luminance.stats();
+    double min = stats(0, 0)[0];
+    double max = stats(1, 0)[0];
+    if (min != max) {
+      // Extract chroma
+      VImage chroma = lab.extract_band(1, VImage::option()->set("n", 2));
+      // Calculate multiplication factor and addition
+      double f = 100.0 / (max - min);
+      double a = -(min * f);
+      // Scale luminance, join to chroma, convert back to original colourspace
+      VImage normalized = luminance.linear(f, a).bandjoin(chroma).colourspace(typeBeforeNormalize);
+      // Attach original alpha channel, if any
+      if (HasAlpha(image)) {
+        // Extract original alpha channel
+        VImage alpha = image[image.bands() - 1];
+        // Join alpha channel to normalised image
+        return normalized.bandjoin(alpha);
+      } else {
+        return normalized;
+      }
+    }
+    return image;
+  }
+
+  /*
+   * Gamma encoding/decoding
+   */
+  VImage Gamma(VImage image, double const exponent) {
+    if (HasAlpha(image)) {
+      // Separate alpha channel
+      VImage alpha = image[image.bands() - 1];
+      return RemoveAlpha(image).gamma(VImage::option()->set("exponent", exponent)).bandjoin(alpha);
+    } else {
+      return image.gamma(VImage::option()->set("exponent", exponent));
+    }
+  }
+
+  /*
+   * Gaussian blur. Use sigma of -1.0 for fast blur.
+   */
+  VImage Blur(VImage image, double const sigma) {
+    if (sigma == -1.0) {
+      // Fast, mild blur - averages neighbouring pixels
+      VImage blur = VImage::new_matrixv(3, 3,
+        1.0, 1.0, 1.0,
+        1.0, 1.0, 1.0,
+        1.0, 1.0, 1.0);
+      blur.set("scale", 9.0);
+      return image.conv(blur);
+    } else {
+      // Slower, accurate Gaussian blur
+      return image.gaussblur(sigma);
+    }
+  }
+
+  /*
+   * Convolution with a kernel.
+   */
+  VImage Convolve(VImage image, int const width, int const height,
+    double const scale, double const offset,
+    std::unique_ptr<double[]> const &kernel_v
+  ) {
+    VImage kernel = VImage::new_from_memory(
+      kernel_v.get(),
+      width * height * sizeof(double),
+      width,
+      height,
+      1,
+      VIPS_FORMAT_DOUBLE);
+    kernel.set("scale", scale);
+    kernel.set("offset", offset);
+
+    return image.conv(kernel);
+  }
+
+  /*
+   * Sharpen flat and jagged areas. Use sigma of -1.0 for fast sharpen.
+   */
+  VImage Sharpen(VImage image, double const sigma, double const flat, double const jagged) {
+    if (sigma == -1.0) {
+      // Fast, mild sharpen
+      VImage sharpen = VImage::new_matrixv(3, 3,
+        -1.0, -1.0, -1.0,
+        -1.0, 32.0, -1.0,
+        -1.0, -1.0, -1.0);
+      sharpen.set("scale", 24.0);
+      return image.conv(sharpen);
+    } else {
+      // Slow, accurate sharpen in LAB colour space, with control over flat vs jagged areas
+      VipsInterpretation colourspaceBeforeSharpen = image.interpretation();
+      if (colourspaceBeforeSharpen == VIPS_INTERPRETATION_RGB) {
+        colourspaceBeforeSharpen = VIPS_INTERPRETATION_sRGB;
+      }
+      return image.sharpen(
+        VImage::option()->set("sigma", sigma)->set("m1", flat)->set("m2", jagged))
+        .colourspace(colourspaceBeforeSharpen);
+    }
+  }
+
+  VImage Threshold(VImage image, double const threshold, bool const thresholdGrayscale) {
+    if (!thresholdGrayscale) {
+      return image >= threshold;
+    }
+    return image.colourspace(VIPS_INTERPRETATION_B_W) >= threshold;
+  }
+
+  /*
+    Perform boolean/bitwise operation on image color channels - results in one channel image
+  */
+  VImage Bandbool(VImage image, VipsOperationBoolean const boolean) {
+    image = image.bandbool(boolean);
+    return image.copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_B_W));
+  }
+
+  /*
+    Perform bitwise boolean operation between images
+  */
+  VImage Boolean(VImage image, VImage imageR, VipsOperationBoolean const boolean) {
+    return image.boolean(imageR, boolean);
+  }
+
+  /*
+    Trim an image
+  */
+  VImage Trim(VImage image, double const threshold) {
+    // Top-left pixel provides the background colour
+    VImage background = image.extract_area(0, 0, 1, 1);
+    if (HasAlpha(background)) {
+      background = background.flatten();
+    }
+    int top, width, height;
+    int const left = image.find_trim(&top, &width, &height, VImage::option()
+      ->set("background", background(0, 0))
+      ->set("threshold", threshold));
+    if (width == 0 || height == 0) {
+      throw VError("Unexpected error while trimming. Try to lower the tolerance");
+    }
+    return image.extract_area(left, top, width, height);
+  }
+
+  /*
+   * Calculate (a * in + b)
+   */
+  VImage Linear(VImage image, double const a, double const b) {
+    if (HasAlpha(image)) {
+      // Separate alpha channel
+      VImage alpha = image[image.bands() - 1];
+      return RemoveAlpha(image).linear(a, b).bandjoin(alpha);
+    } else {
+      return image.linear(a, b);
+    }
+  }
+}  // namespace sharp

src/operations.h

@@ -0,0 +1,112 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_OPERATIONS_H_
+#define SRC_OPERATIONS_H_
+
+#include <algorithm>
+#include <functional>
+#include <memory>
+#include <tuple>
+#include <vips/vips8>
+
+using vips::VImage;
+
+namespace sharp {
+
+  /*
+    Removes alpha channel, if any.
+  */
+  VImage RemoveAlpha(VImage image);
+
+  /*
+    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);
+
+  /*
+    Composite overlayImage over image at given position
+   */
+  VImage Composite(VImage image, VImage overlayImage, int const x, int const y);
+
+  /*
+    Alpha composite overlayImage over image, assumes matching dimensions
+  */
+  VImage AlphaComposite(VImage image, VImage overlayImage);
+
+  /*
+    Cutout src over dst with given gravity.
+  */
+  VImage Cutout(VImage src, VImage dst, const int gravity);
+
+  /*
+   * Tint an image using the specified chroma, preserving the original image luminance
+   */
+  VImage Tint(VImage image, double const a, double const b);
+
+  /*
+   * Stretch luminance to cover full dynamic range.
+   */
+  VImage Normalise(VImage image);
+
+  /*
+   * Gamma encoding/decoding
+   */
+  VImage Gamma(VImage image, double const exponent);
+
+  /*
+   * Gaussian blur. Use sigma of -1.0 for fast blur.
+   */
+  VImage Blur(VImage image, double const sigma);
+
+  /*
+   * Convolution with a kernel.
+   */
+  VImage Convolve(VImage image, int const width, int const height,
+    double const scale, double const offset, std::unique_ptr<double[]> const &kernel_v);
+
+  /*
+   * Sharpen flat and jagged areas. Use sigma of -1.0 for fast sharpen.
+   */
+  VImage Sharpen(VImage image, double const sigma, double const flat, double const jagged);
+
+  /*
+    Threshold an image
+  */
+  VImage Threshold(VImage image, double const threshold, bool const thresholdColor);
+
+  /*
+    Perform boolean/bitwise operation on image color channels - results in one channel image
+  */
+  VImage Bandbool(VImage image, VipsOperationBoolean const boolean);
+
+  /*
+    Perform bitwise boolean operation between images
+  */
+  VImage Boolean(VImage image, VImage imageR, VipsOperationBoolean const boolean);
+
+  /*
+    Trim an image
+  */
+  VImage Trim(VImage image, double const threshold);
+
+  /*
+   * Linear adjustment (a * in + b)
+   */
+  VImage Linear(VImage image, double const a, double const b);
+
+}  // namespace sharp
+
+#endif  // SRC_OPERATIONS_H_

src/pipeline.h

@@ -0,0 +1,239 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_PIPELINE_H_
+#define SRC_PIPELINE_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <nan.h>
+#include <vips/vips8>
+
+#include "./common.h"
+
+NAN_METHOD(pipeline);
+
+enum class Canvas {
+  CROP,
+  EMBED,
+  MAX,
+  MIN,
+  IGNORE_ASPECT
+};
+
+struct 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 position;
+  std::vector<double> resizeBackground;
+  bool hasCropOffset;
+  int cropOffsetLeft;
+  int cropOffsetTop;
+  bool premultiplied;
+  std::string kernel;
+  bool fastShrinkOnLoad;
+  double tintA;
+  double tintB;
+  bool flatten;
+  std::vector<double> flattenBackground;
+  bool negate;
+  double blurSigma;
+  int medianSize;
+  double sharpenSigma;
+  double sharpenFlat;
+  double sharpenJagged;
+  int threshold;
+  bool thresholdGrayscale;
+  double trimThreshold;
+  int trimOffsetLeft;
+  int trimOffsetTop;
+  double linearA;
+  double linearB;
+  double gamma;
+  bool greyscale;
+  bool normalise;
+  bool useExifOrientation;
+  int angle;
+  double rotationAngle;
+  std::vector<double> rotationBackground;
+  bool rotateBeforePreExtract;
+  bool flip;
+  bool flop;
+  int extendTop;
+  int extendBottom;
+  int extendLeft;
+  int extendRight;
+  std::vector<double> extendBackground;
+  bool withoutEnlargement;
+  VipsAccess accessMethod;
+  int jpegQuality;
+  bool jpegProgressive;
+  std::string jpegChromaSubsampling;
+  bool jpegTrellisQuantisation;
+  int jpegQuantisationTable;
+  bool jpegOvershootDeringing;
+  bool jpegOptimiseScans;
+  bool jpegOptimiseCoding;
+  bool pngProgressive;
+  int pngCompressionLevel;
+  bool pngAdaptiveFiltering;
+  int webpQuality;
+  int webpAlphaQuality;
+  bool webpNearLossless;
+  bool webpLossless;
+  int tiffQuality;
+  VipsForeignTiffCompression tiffCompression;
+  VipsForeignTiffPredictor tiffPredictor;
+  bool tiffSquash;
+  double tiffXres;
+  double tiffYres;
+  std::string err;
+  bool withMetadata;
+  int withMetadataOrientation;
+  std::unique_ptr<double[]> convKernel;
+  int convKernelWidth;
+  int convKernelHeight;
+  double convKernelScale;
+  double convKernelOffset;
+  sharp::InputDescriptor *boolean;
+  VipsOperationBoolean booleanOp;
+  VipsOperationBoolean bandBoolOp;
+  int extractChannel;
+  bool removeAlpha;
+  VipsInterpretation colourspace;
+  int tileSize;
+  int tileOverlap;
+  VipsForeignDzContainer tileContainer;
+  VipsForeignDzLayout tileLayout;
+  std::string tileFormat;
+  int tileAngle;
+  VipsForeignDzDepth tileDepth;
+
+  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),
+    position(0),
+    resizeBackground{ 0.0, 0.0, 0.0, 255.0 },
+    hasCropOffset(false),
+    cropOffsetLeft(0),
+    cropOffsetTop(0),
+    premultiplied(false),
+    tintA(128.0),
+    tintB(128.0),
+    flatten(false),
+    flattenBackground{ 0.0, 0.0, 0.0 },
+    negate(false),
+    blurSigma(0.0),
+    medianSize(0),
+    sharpenSigma(0.0),
+    sharpenFlat(1.0),
+    sharpenJagged(2.0),
+    threshold(0),
+    thresholdGrayscale(true),
+    trimThreshold(0.0),
+    trimOffsetLeft(0),
+    trimOffsetTop(0),
+    linearA(1.0),
+    linearB(0.0),
+    gamma(0.0),
+    greyscale(false),
+    normalise(false),
+    useExifOrientation(false),
+    angle(0),
+    rotationAngle(0.0),
+    rotationBackground{ 0.0, 0.0, 0.0, 255.0 },
+    flip(false),
+    flop(false),
+    extendTop(0),
+    extendBottom(0),
+    extendLeft(0),
+    extendRight(0),
+    extendBackground{ 0.0, 0.0, 0.0, 255.0 },
+    withoutEnlargement(false),
+    jpegQuality(80),
+    jpegProgressive(false),
+    jpegChromaSubsampling("4:2:0"),
+    jpegTrellisQuantisation(false),
+    jpegQuantisationTable(0),
+    jpegOvershootDeringing(false),
+    jpegOptimiseScans(false),
+    jpegOptimiseCoding(true),
+    pngProgressive(false),
+    pngCompressionLevel(9),
+    pngAdaptiveFiltering(false),
+    webpQuality(80),
+    tiffQuality(80),
+    tiffCompression(VIPS_FOREIGN_TIFF_COMPRESSION_JPEG),
+    tiffPredictor(VIPS_FOREIGN_TIFF_PREDICTOR_HORIZONTAL),
+    tiffSquash(false),
+    tiffXres(1.0),
+    tiffYres(1.0),
+    withMetadata(false),
+    withMetadataOrientation(-1),
+    convKernelWidth(0),
+    convKernelHeight(0),
+    convKernelScale(0.0),
+    convKernelOffset(0.0),
+    boolean(nullptr),
+    booleanOp(VIPS_OPERATION_BOOLEAN_LAST),
+    bandBoolOp(VIPS_OPERATION_BOOLEAN_LAST),
+    extractChannel(-1),
+    removeAlpha(false),
+    colourspace(VIPS_INTERPRETATION_LAST),
+    tileSize(256),
+    tileOverlap(0),
+    tileContainer(VIPS_FOREIGN_DZ_CONTAINER_FS),
+    tileLayout(VIPS_FOREIGN_DZ_LAYOUT_DZ),
+    tileAngle(0),
+    tileDepth(VIPS_FOREIGN_DZ_DEPTH_LAST) {}
+};
+
+#endif  // SRC_PIPELINE_H_

src/sharp.cc

@@ -1,173 +1,54 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 #include <node.h>
-#include <math.h>
-#include <string>
-#include <vector>
-#include <vips/vips.h>
+#include <nan.h>
+#include <vips/vips8>
 
-using namespace v8;
+#include "common.h"
+#include "metadata.h"
+#include "pipeline.h"
+#include "utilities.h"
+#include "stats.h"
 
-// Free VipsImage children when object goes out of scope
-// Thanks due to https://github.com/dosx/node-vips
-class ImageFreer {
-  public:
-    ImageFreer() {}
-    ~ImageFreer() {
-      for (uint16_t i = 0; i < v_.size(); i++) {
-        if (v_[i] != NULL) {
-          g_object_unref(v_[i]);
-        }
-      }
-      v_.clear();
-    }
-    void add(VipsImage* i) { v_.push_back(i); }
-  private:
-    std::vector<VipsImage*> v_;
-};
+NAN_MODULE_INIT(init) {
+  vips_init("sharp");
 
-struct ResizeBaton {
-  std::string src;
-  std::string dst;
-  int  cols;
-  int  rows;
-  bool crop;
-  int  embed;
-  std::string err;
-  Persistent<Function> callback;
-};
+  g_log_set_handler("VIPS", static_cast<GLogLevelFlags>(G_LOG_LEVEL_WARNING),
+    static_cast<GLogFunc>(sharp::VipsWarningCallback), nullptr);
 
-void ResizeAsync(uv_work_t *work) {
-  ResizeBaton* baton = static_cast<ResizeBaton*>(work->data);
-
-  VipsImage *in = vips_image_new_mode((baton->src).c_str(), "p");
-  im_jpeg2vips((baton->src).c_str(), in);
-  if (in == NULL) {
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-    return;
-  }
-  ImageFreer freer;
-  freer.add(in);
-
-  VipsImage* img = in;
-  VipsImage* t[4];
-
-  if (im_open_local_array(img, t, 4, "temp", "p")) {
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-    return;
-  }
-
-  double xfactor = static_cast<double>(img->Xsize) / std::max(baton->cols, 1);
-  double yfactor = static_cast<double>(img->Ysize) / std::max(baton->rows, 1);
-  double factor = baton->crop ? std::min(xfactor, yfactor) : std::max(xfactor, yfactor);
-  factor = std::max(factor, 1.0);
-  int shrink = floor(factor);
-  double residual = shrink / factor;
-
-  // Use im_shrink with the integral reduction
-  if (im_shrink(img, t[0], shrink, shrink)) {
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-    return;
-  }
-
-  // Use im_affinei with the remaining float part using bilinear interpolation
-  if (im_affinei_all(t[0], t[1], vips_interpolate_bilinear_static(), residual, 0, 0, residual, 0, 0)) {
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-    return;
-  }
-  img = t[1];
-
-  if (baton->crop) {
-    int width = std::min(img->Xsize, baton->cols);
-    int height = std::min(img->Ysize, baton->rows);
-    int left = (img->Xsize - width + 1) / 2;
-    int top = (img->Ysize - height + 1) / 2;
-    if (im_extract_area(img, t[2], left, top, width, height)) {
-      (baton->err).append(vips_error_buffer());
-      vips_error_clear();
-      return;
-    }
-    img = t[2];
-  } else {
-    int left = (baton->cols - img->Xsize) / 2;
-    int top = (baton->rows - img->Ysize) / 2;
-    if (im_embed(img, t[2], baton->embed, left, top, baton->cols, baton->rows)) {
-      (baton->err).append(vips_error_buffer());
-      vips_error_clear();
-      return;
-    }
-    img = t[2];
-  }
-
-  // Mild sharpen
-  INTMASK* sharpen = im_create_imaskv("sharpen", 3, 3,
-    -1, -1, -1,
-    -1, 32, -1,
-    -1, -1, -1);
-  sharpen->scale = 24;
-  if (im_conv(img, t[3], sharpen)) { 
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-    return;
-  }
-  img = t[3];
-
-  if (im_vips2jpeg(img, baton->dst.c_str())) {
-    (baton->err).append(vips_error_buffer());
-    vips_error_clear();
-  }  
+  // Methods available to JavaScript
+  Nan::Set(target, Nan::New("metadata").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(metadata)).ToLocalChecked());
+  Nan::Set(target, Nan::New("pipeline").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(pipeline)).ToLocalChecked());
+  Nan::Set(target, Nan::New("cache").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(cache)).ToLocalChecked());
+  Nan::Set(target, Nan::New("concurrency").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(concurrency)).ToLocalChecked());
+  Nan::Set(target, Nan::New("counters").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(counters)).ToLocalChecked());
+  Nan::Set(target, Nan::New("simd").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(simd)).ToLocalChecked());
+  Nan::Set(target, Nan::New("libvipsVersion").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(libvipsVersion)).ToLocalChecked());
+  Nan::Set(target, Nan::New("format").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(format)).ToLocalChecked());
+  Nan::Set(target, Nan::New("_maxColourDistance").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(_maxColourDistance)).ToLocalChecked());
+  Nan::Set(target, Nan::New("stats").ToLocalChecked(),
+    Nan::GetFunction(Nan::New<v8::FunctionTemplate>(stats)).ToLocalChecked());
 }
 
-void ResizeAsyncAfter(uv_work_t *work, int status) {
-  HandleScope scope;
-
-  ResizeBaton *baton = static_cast<ResizeBaton*>(work->data);
-
-  Local<Value> argv[1];
-  if (!baton->err.empty()) {
-    argv[0] = String::New(baton->err.data(), baton->err.size());
-  } else {
-    argv[0] = Local<Value>::New(Null());
-  }
-
-  baton->callback->Call(Context::GetCurrent()->Global(), 1, argv);
-  baton->callback.Dispose();
-  delete baton;
-  delete work;
-}
-
-Handle<Value> Resize(const Arguments& args) {
-  HandleScope scope;
-  
-  ResizeBaton *baton = new ResizeBaton;
-  baton->src = *String::Utf8Value(args[0]->ToString());
-  baton->dst = *String::Utf8Value(args[1]->ToString());
-  baton->cols = args[2]->Int32Value();
-  baton->rows = args[3]->Int32Value();
-  Local<String> canvas = args[4]->ToString();
-  if (canvas->Equals(String::NewSymbol("c"))) {
-	baton->crop = true;
-  } else if (canvas->Equals(String::NewSymbol("w"))) {
-    baton->crop = false;
-    baton->embed = 4;
-  } else if (canvas->Equals(String::NewSymbol("b"))) {
-    baton->crop = false;
-    baton->embed = 0;
-  }	
-  baton->callback = Persistent<Function>::New(Local<Function>::Cast(args[5]));
-
-  uv_work_t *work = new uv_work_t;
-  work->data = baton;
-  uv_queue_work(uv_default_loop(), work, ResizeAsync, (uv_after_work_cb)ResizeAsyncAfter);
-  return Undefined();
-}
-
-extern "C" void init(Handle<Object> target) {
-  HandleScope scope;
-  vips_init("");
-  NODE_SET_METHOD(target, "resize", Resize);
-};
-
 NODE_MODULE(sharp, init)

src/stats.cc

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

src/stats.h

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

src/utilities.cc

@@ -0,0 +1,271 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cmath>
+#include <string>
+
+#include <node.h>
+#include <nan.h>
+#include <vips/vips8>
+#include <vips/vector.h>
+
+#include "common.h"
+#include "operations.h"
+#include "utilities.h"
+
+using 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 const &err) {
+    return ThrowError(err.what());
+  }
+
+  // Clean up libvips' per-request data and threads
+  vips_error_clear();
+  vips_thread_shutdown();
+
+  info.GetReturnValue().Set(New<Number>(maxColourDistance));
+}

src/utilities.h

@@ -0,0 +1,28 @@
+// 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
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_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 +1,24 @@
+{
+  "name": "sharp-benchmark",
+  "version": "0.0.1",
+  "private": true,
+  "author": "Lovell Fuller <npm@lovell.info>",
+  "description": "Benchmark and performance tests for sharp",
+  "scripts": {
+    "test": "node perf && node random && node parallel"
+  },
+  "devDependencies": {
+    "async": "^2.6.1",
+    "benchmark": "^2.1.4",
+    "gm": "^1.23.1",
+    "imagemagick": "^0.1.3",
+    "imagemagick-native": "^1.9.3",
+    "jimp": "^0.5.3",
+    "mapnik": "^4.0.1",
+    "semver": "^5.5.1"
+  },
+  "license": "Apache-2.0",
+  "engines": {
+    "node": ">=6"
+  }
+}

test/bench/parallel.js

@@ -0,0 +1,45 @@
+'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);
+      ids.sort();
+      const mean = ids.reduce(function (a, b) {
+        return a + b;
+      }) / ids.length;
+      console.log(parallelism + ' parallel calls: fastest=' + ids[0] + 'ms slowest=' + ids[ids.length - 1] + 'ms mean=' + mean + 'ms');
+      next();
+    }
+  );
+}, function () {
+  clearInterval(timer);
+  console.dir(sharp.counters());
+});

test/bench/perf.js

@@ -0,0 +1,911 @@
+'use strict';
+
+const fs = require('fs');
+
+const async = require('async');
+const assert = require('assert');
+const Benchmark = require('benchmark');
+
+// Contenders
+const sharp = require('../../');
+const gm = require('gm');
+const imagemagick = require('imagemagick');
+const mapnik = require('mapnik');
+const jimp = require('jimp');
+let imagemagickNative;
+try {
+  imagemagickNative = require('imagemagick-native');
+} catch (err) {
+  console.log('Excluding imagemagick-native');
+}
+
+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);
+
+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, jimp.RESIZE_BICUBIC)
+              .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, jimp.RESIZE_BICUBIC)
+              .quality(80)
+              .write(fixtures.outputJpg, function (err) {
+                if (err) {
+                  throw err;
+                } else {
+                  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, { max_size: 3000 }, 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, {
+            fit: 'cover',
+            position: 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, {
+            fit: 'cover',
+            position: 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();
+  },
+  // Comparative 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();
+                }
+              });
+          }
+        });
+      }
+    });
+    // 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, { max_size: 3000 }, 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-adaptiveFiltering', {
+      defer: true,
+      fn: function (deferred) {
+        sharp(inputPngBuffer)
+          .resize(width, height)
+          .png({ adaptiveFiltering: true })
+          .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();

test/coverage/report.sh

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