Release v0.28.3

docs/api-channel.md

@@ -4,6 +4,8 @@
 
 Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
 
+See also [flatten][1].
+
 ### Examples
 
 ```javascript
@@ -25,7 +27,7 @@ This is a no-op if the image already has an alpha channel.
 
 ### Parameters
 
-*   `alpha` **[number][1]** alpha transparency level (0=fully-transparent, 1=fully-opaque) (optional, default `1`)
+*   `alpha` **[number][2]** alpha transparency level (0=fully-transparent, 1=fully-opaque) (optional, default `1`)
 
 ### Examples
 
@@ -43,7 +45,7 @@ const rgba = await sharp(rgb)
   .toBuffer();
 ```
 
-*   Throws **[Error][2]** Invalid alpha transparency level
+*   Throws **[Error][3]** Invalid alpha transparency level
 
 Returns **Sharp** 
 
@@ -57,7 +59,7 @@ Extract a single channel from a multi-channel image.
 
 ### Parameters
 
-*   `channel` **([number][1] | [string][3])** zero-indexed channel/band number to extract, or `red`, `green`, `blue` or `alpha`.
+*   `channel` **([number][2] | [string][4])** zero-indexed channel/band number to extract, or `red`, `green`, `blue` or `alpha`.
 
 ### Examples
 
@@ -71,7 +73,7 @@ sharp(input)
    });
 ```
 
-*   Throws **[Error][2]** Invalid channel
+*   Throws **[Error][3]** Invalid channel
 
 Returns **Sharp** 
 
@@ -90,12 +92,12 @@ For raw pixel input, the `options` object should contain a `raw` attribute, whic
 
 ### Parameters
 
-*   `images` **([Array][4]<([string][3] | [Buffer][5])> | [string][3] | [Buffer][5])** one or more images (file paths, Buffers).
+*   `images` **([Array][5]<([string][4] | [Buffer][6])> | [string][4] | [Buffer][6])** one or more images (file paths, Buffers).
-*   `options` **[Object][6]** image options, see `sharp()` constructor.
+*   `options` **[Object][7]** image options, see `sharp()` constructor.
 
 <!---->
 
-*   Throws **[Error][2]** Invalid parameters
+*   Throws **[Error][3]** Invalid parameters
 
 Returns **Sharp** 
 
@@ -105,7 +107,7 @@ Perform a bitwise boolean operation on all input image channels (bands) to produ
 
 ### Parameters
 
-*   `boolOp` **[string][3]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+*   `boolOp` **[string][4]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
 
 ### Examples
 
@@ -119,18 +121,20 @@ sharp('3-channel-rgb-input.png')
   });
 ```
 
-*   Throws **[Error][2]** Invalid parameters
+*   Throws **[Error][3]** Invalid parameters
 
 Returns **Sharp** 
 
-[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+[1]: /api-operation#flatten
 
-[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
 
-[3]: 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
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
 
-[5]: https://nodejs.org/api/buffer.html
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
 
-[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+[6]: https://nodejs.org/api/buffer.html
+
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

docs/api-composite.md

@@ -41,6 +41,8 @@ and [https://www.cairographics.org/operators/][2]
         *   `images[].raw.width` **[Number][7]?** 
         *   `images[].raw.height` **[Number][7]?** 
         *   `images[].raw.channels` **[Number][7]?** 
+    *   `images[].failOnError` **[boolean][9]** @see [constructor parameters][10] (optional, default `true`)
+    *   `images[].limitInputPixels` **([number][7] | [boolean][9])** @see [constructor parameters][10] (optional, default `268402689`)
 
 ### Examples
 
@@ -61,7 +63,7 @@ sharp('input.png')
   });
 ```
 
-*   Throws **[Error][10]** Invalid parameters
+*   Throws **[Error][11]** Invalid parameters
 
 Returns **Sharp** 
 
@@ -87,4 +89,6 @@ Returns **Sharp**
 
 [9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
 
-[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+[10]: /api-constructor#parameters
+
+[11]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

docs/api-operation.md

@@ -176,6 +176,8 @@ Returns **Sharp**
 
 Merge alpha transparency channel, if any, with a background, then remove the alpha channel.
 
+See also [removeAlpha][8].
+
 ### Parameters
 
 *   `options` **[Object][2]?** 
@@ -186,7 +188,7 @@ Merge alpha transparency channel, if any, with a background, then remove the alp
 
 ```javascript
 await sharp(rgbaInput)
-  .flatten({background: '#F0A703' })
+  .flatten({ background: '#F0A703' })
   .toBuffer();
 ```
 
@@ -243,6 +245,33 @@ Alternative spelling of normalise.
 
 Returns **Sharp** 
 
+## clahe
+
+Perform contrast limiting adaptive histogram equalization
+[CLAHE][9].
+
+This will, in general, enhance the clarity of the image by bringing out darker details.
+
+### Parameters
+
+*   `options` **[Object][2]** 
+
+    *   `options.width` **[number][1]** integer width of the region in pixels.
+    *   `options.height` **[number][1]** integer height of the region in pixels.
+    *   `options.maxSlope` **[number][1]** maximum value for the slope of the
+        cumulative histogram. A value of 0 disables contrast limiting. Valid values
+        are integers in the range 0-100 (inclusive) (optional, default `3`)
+
+<!---->
+
+*   Throws **[Error][5]** Invalid parameters
+
+Returns **Sharp** 
+
+**Meta**
+
+*   **since**: 0.28.3
+
 ## convolve
 
 Convolve the image with the specified kernel.
@@ -252,7 +281,7 @@ Convolve the image with the specified kernel.
 *   `kernel` **[Object][2]** 
 
     *   `kernel.width` **[number][1]** width of the kernel in pixels.
-    *   `kernel.height` **[number][1]** width of the kernel in pixels.
+    *   `kernel.height` **[number][1]** height of the kernel in pixels.
     *   `kernel.kernel` **[Array][7]<[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`)
@@ -304,7 +333,7 @@ the selected bitwise boolean `operation` between the corresponding pixels of the
 
 ### Parameters
 
-*   `operand` **([Buffer][8] | [string][3])** Buffer containing image data or string containing the path to an image file.
+*   `operand` **([Buffer][10] | [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]?** 
 
@@ -421,4 +450,8 @@ Returns **Sharp**
 
 [7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
 
-[8]: https://nodejs.org/api/buffer.html
+[8]: /api-channel#removealpha
+
+[9]: https://en.wikipedia.org/wiki/Adaptive_histogram_equalization#Contrast_Limited_AHE
+
+[10]: https://nodejs.org/api/buffer.html

docs/changelog.md

@@ -4,6 +4,17 @@
 
 Requires libvips v8.10.6
 
+### v0.28.3 - 24th May 2021
+
+* Ensure presence of libvips, vendored or global, before invoking node-gyp.
+
+* Skip shrink-on-load for multi-page WebP.
+  [#2714](https://github.com/lovell/sharp/issues/2714)
+
+* Add contrast limiting adaptive histogram equalization (CLAHE) operator.
+  [#2726](https://github.com/lovell/sharp/pull/2726)
+  [@baparham](https://github.com/baparham)
+
 ### v0.28.2 - 10th May 2021
 
 * Allow `withMetadata` to set `density`.

docs/index.html

@@ -19,7 +19,7 @@
   <link rel="apple-touch-icon-precomposed" sizes="72x72" href="https://pixel.plumbing/px/72x72/sharp-logo.svg">
   <link rel="apple-touch-icon-precomposed" href="https://pixel.plumbing/px/57x57/sharp-logo.svg">
   <link rel="author" href="/humans.txt" type="text/plain">
-  <link rel="preload" href="https://cdn.jsdelivr.net/gh/lovell/sharp@v0.28.2/docs/README.md" as="fetch" type="text/markdown" crossorigin>
+  <link rel="preload" href="https://cdn.jsdelivr.net/gh/lovell/sharp@v0.28.3/docs/README.md" as="fetch" type="text/markdown" crossorigin>
   <link rel="preload" href="https://cdn.jsdelivr.net/gh/lovell/sharp@master/docs/image/sharp-logo.svg" as="image" type="image/svg+xml" crossorigin>
   <link rel="dns-prefetch" href="https://pixel.plumbing">
   <link rel="dns-prefetch" href="https://www.google-analytics.com">
@@ -139,7 +139,7 @@
         docuteApiTitlePlugin,
         docuteApiSearchPlugin
       ],
-      sourcePath: 'https://cdn.jsdelivr.net/gh/lovell/sharp@v0.28.2/docs',
+      sourcePath: 'https://cdn.jsdelivr.net/gh/lovell/sharp@v0.28.3/docs',
       nav: [
         {
           title: 'Funding',

docs/search-index/build.js

@@ -2,7 +2,7 @@
 
 const fs = require('fs');
 const path = require('path');
-const { extractDescription, extractKeywords } = require('./extract');
+const { extractDescription, extractKeywords, extractParameters } = require('./extract');
 
 const searchIndex = [];
 
@@ -37,18 +37,19 @@ for (const match of matches) {
 ].forEach((section) => {
   const contents = fs.readFileSync(path.join(__dirname, '..', `api-${section}.md`), 'utf8');
   const matches = contents.matchAll(
-    /\n## (?<title>[A-Za-z]+)\n\n(?<firstparagraph>.+?)\n\n/gs
+    /\n## (?<title>[A-Za-z]+)\n\n(?<firstparagraph>.+?)\n\n(?<parameters>### Parameters.+?Returns)?/gs
   );
   for (const match of matches) {
-    const { title, firstparagraph } = match.groups;
+    const { title, firstparagraph, parameters } = match.groups;
     const description = firstparagraph.startsWith('###')
       ? 'Constructor'
       : extractDescription(firstparagraph);
+    const parameterNames = parameters ? extractParameters(parameters) : '';
 
     searchIndex.push({
       t: title,
       d: description,
-      k: extractKeywords(`${title} ${description}`),
+      k: extractKeywords(`${title} ${description} ${parameterNames}`),
       l: `/api-${section}#${title.toLowerCase()}`
     });
   }

docs/search-index/extract.js

@@ -4,6 +4,7 @@ const stopWords = require('./stop-words');
 
 const extractDescription = (str) =>
   str
+    .replace(/### Examples.*/sg, '')
     .replace(/\(http[^)]+/g, '')
     .replace(/\s+/g, ' ')
     .replace(/[^A-Za-z0-9_/\-,. ]/g, '')
@@ -11,6 +12,11 @@ const extractDescription = (str) =>
     .substr(0, 180)
     .trim();
 
+const extractParameters = (str) =>
+  [...str.matchAll(/options\.(?<name>[^.`]+)/gs)]
+    .map((match) => match.groups.name)
+    .join(' ');
+
 const extractKeywords = (str) =>
   [
     ...new Set(
@@ -21,4 +27,4 @@ const extractKeywords = (str) =>
     )
   ].join(' ');
 
-module.exports = { extractDescription, extractKeywords };
+module.exports = { extractDescription, extractKeywords, extractParameters };

docs/search-index/stop-words.js

@@ -17,6 +17,7 @@ module.exports = [
   'before',
   'both',
   'call',
+  'callback',
   'can',
   'containing',
   'default',
@@ -26,6 +27,7 @@ module.exports = [
   'ensure',
   'etc',
   'every',
+  'except',
   'for',
   'from',
   'get',
@@ -49,12 +51,16 @@ module.exports = [
   'occur',
   'occurs',
   'options',
+  'other',
+  'out',
   'over',
   'perform',
   'performs',
   'provide',
   'provided',
   'ready',
+  'requires',
+  'returned',
   'same',
   'see',
   'set',
@@ -67,9 +73,11 @@ module.exports = [
   'supported',
   'sure',
   'take',
+  'than',
   'that',
   'the',
   'their',
+  'then',
   'there',
   'therefore',
   'these',

install/can-compile.js

@@ -0,0 +1,11 @@
+'use strict';
+
+const libvips = require('../lib/libvips');
+
+try {
+  if (!(libvips.useGlobalLibvips() || libvips.hasVendoredLibvips())) {
+    process.exitCode = 1;
+  }
+} catch (err) {
+  process.exitCode = 1;
+}

install/libvips.js

@@ -43,7 +43,6 @@ const fail = function (err) {
   if (err.code === 'EACCES') {
     libvips.log('Are you trying to install as a root or sudo user? Try again with the --unsafe-perm flag');
   }
-  libvips.log('Attempting to build from source via node-gyp but this may fail due to the above error');
   libvips.log('Please see https://sharp.pixelplumbing.com/install for required dependencies');
   process.exit(1);
 };

lib/channel.js

@@ -15,6 +15,8 @@ const bool = {
 /**
  * Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
  *
+ * See also {@link /api-operation#flatten|flatten}.
+ *
  * @example
  * sharp('rgba.png')
  *   .removeAlpha()

lib/composite.js

@@ -89,6 +89,8 @@ const blend = {
  * @param {Number} [images[].raw.width]
  * @param {Number} [images[].raw.height]
  * @param {Number} [images[].raw.channels]
+ * @param {boolean} [images[].failOnError=true] - @see {@link /api-constructor#parameters|constructor parameters}
+ * @param {number|boolean} [images[].limitInputPixels=268402689] - @see {@link /api-constructor#parameters|constructor parameters}
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
  */

lib/constructor.js

@@ -216,6 +216,9 @@ const Sharp = function (input, options) {
     gammaOut: 0,
     greyscale: false,
     normalise: false,
+    claheWidth: 0,
+    claheHeight: 0,
+    claheMaxSlope: 3,
     brightness: 1,
     saturation: 1,
     hue: 0,

lib/operation.js

@@ -270,9 +270,11 @@ function blur (sigma) {
 /**
  * Merge alpha transparency channel, if any, with a background, then remove the alpha channel.
  *
+ * See also {@link /api-channel#removealpha|removeAlpha}.
+ *
  * @example
  * await sharp(rgbaInput)
- *   .flatten({background: '#F0A703' })
+ *   .flatten({ background: '#F0A703' })
  *   .toBuffer();
  *
  * @param {Object} [options]
@@ -350,6 +352,47 @@ function normalize (normalize) {
   return this.normalise(normalize);
 }
 
+/**
+ * Perform contrast limiting adaptive histogram equalization
+ * {@link https://en.wikipedia.org/wiki/Adaptive_histogram_equalization#Contrast_Limited_AHE|CLAHE}.
+ *
+ * This will, in general, enhance the clarity of the image by bringing out darker details.
+ *
+ * @since 0.28.3
+ *
+ * @param {Object} options
+ * @param {number} options.width - integer width of the region in pixels.
+ * @param {number} options.height - integer height of the region in pixels.
+ * @param {number} [options.maxSlope=3] - maximum value for the slope of the
+ *  cumulative histogram. A value of 0 disables contrast limiting. Valid values
+ *  are integers in the range 0-100 (inclusive)
+ * @returns {Sharp}
+ * @throws {Error} Invalid parameters
+ */
+function clahe (options) {
+  if (!is.plainObject(options)) {
+    throw is.invalidParameterError('options', 'plain object', options);
+  }
+  if (!('width' in options) || !is.integer(options.width) || options.width <= 0) {
+    throw is.invalidParameterError('width', 'integer above zero', options.width);
+  } else {
+    this.options.claheWidth = options.width;
+  }
+  if (!('height' in options) || !is.integer(options.height) || options.height <= 0) {
+    throw is.invalidParameterError('height', 'integer above zero', options.height);
+  } else {
+    this.options.claheHeight = options.height;
+  }
+  if (!is.defined(options.maxSlope)) {
+    this.options.claheMaxSlope = 3;
+  } else if (!is.integer(options.maxSlope) || options.maxSlope < 0 || options.maxSlope > 100) {
+    throw is.invalidParameterError('maxSlope', 'integer 0-100', options.maxSlope);
+  } else {
+    this.options.claheMaxSlope = options.maxSlope;
+  }
+  return this;
+}
+
 /**
  * Convolve the image with the specified kernel.
  *
@@ -368,7 +411,7 @@ function normalize (normalize) {
  *
  * @param {Object} kernel
  * @param {number} kernel.width - width of the kernel in pixels.
- * @param {number} kernel.height - width of the kernel in pixels.
+ * @param {number} kernel.height - height 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.
@@ -594,6 +637,7 @@ module.exports = function (Sharp) {
     negate,
     normalise,
     normalize,
+    clahe,
     convolve,
     threshold,
     boolean,

package.json

@@ -1,7 +1,7 @@
 {
   "name": "sharp",
   "description": "High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP, AVIF and TIFF images",
-  "version": "0.28.2",
+  "version": "0.28.3",
   "author": "Lovell Fuller <npm@lovell.info>",
   "homepage": "https://github.com/lovell/sharp",
   "contributors": [
@@ -76,10 +76,11 @@
     "Leon Radley <leon@radley.se>",
     "alza54 <alza54@thiocod.in>",
     "Jacob Smith <jacob@frende.me>",
-    "Michael Nutt <michael@nutt.im>"
+    "Michael Nutt <michael@nutt.im>",
+    "Brad Parham <baparham@gmail.com>"
   ],
   "scripts": {
-    "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node-gyp rebuild && node install/dll-copy)",
+    "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node install/can-compile && node-gyp rebuild && node install/dll-copy)",
     "clean": "rm -rf node_modules/ build/ vendor/ .nyc_output/ coverage/ test/fixtures/output.*",
     "test": "npm run test-lint && npm run test-unit && npm run test-licensing",
     "test-lint": "semistandard && cpplint",
@@ -122,7 +123,7 @@
   "dependencies": {
     "color": "^3.1.3",
     "detect-libc": "^1.0.3",
-    "node-addon-api": "^3.1.0",
+    "node-addon-api": "^3.2.0",
     "prebuild-install": "^6.1.2",
     "semver": "^7.3.5",
     "simple-get": "^3.1.0",

src/operations.cc

@@ -92,6 +92,13 @@ namespace sharp {
     return image;
   }
 
+  /*
+   * Contrast limiting adapative histogram equalization (CLAHE)
+   */
+  VImage Clahe(VImage image, int const width, int const height, int const maxSlope) {
+    return image.hist_local(width, height, VImage::option()->set("max_slope", maxSlope));
+  }
+
   /*
    * Gamma encoding/decoding
    */

src/operations.h

@@ -35,6 +35,11 @@ namespace sharp {
    */
   VImage Normalise(VImage image);
 
+  /*
+   * Contrast limiting adapative histogram equalization (CLAHE)
+   */
+  VImage Clahe(VImage image, int const width, int const height, int const maxSlope);
+
   /*
    * Gamma encoding/decoding
    */

src/pipeline.cc

@@ -227,7 +227,7 @@ class PipelineWorker : public Napi::AsyncWorker {
         xshrink == yshrink && xshrink >= 2 * shrink_on_load_factor &&
         (inputImageType == sharp::ImageType::JPEG || inputImageType == sharp::ImageType::WEBP) &&
         baton->gamma == 0 && baton->topOffsetPre == -1 && baton->trimThreshold == 0.0 &&
-        image.width() > 3 && image.height() > 3
+        image.width() > 3 && image.height() > 3 && baton->input->pages == 1
       ) {
         if (xshrink >= 8 * shrink_on_load_factor) {
           xfactor = xfactor / 8;
@@ -345,6 +345,7 @@ class PipelineWorker : public Napi::AsyncWorker {
       bool const shouldApplyMedian = baton->medianSize > 0;
       bool const shouldComposite = !baton->composite.empty();
       bool const shouldModulate = baton->brightness != 1.0 || baton->saturation != 1.0 || baton->hue != 0.0;
+      bool const shouldApplyClahe = baton->claheWidth != 0 && baton->claheHeight != 0;
 
       if (shouldComposite && !sharp::HasAlpha(image)) {
         image = sharp::EnsureAlpha(image, 1);
@@ -650,6 +651,11 @@ class PipelineWorker : public Napi::AsyncWorker {
         image = sharp::Normalise(image);
       }
 
+      // Apply contrast limiting adaptive histogram equalization (CLAHE)
+      if (shouldApplyClahe) {
+        image = sharp::Clahe(image, baton->claheWidth, baton->claheHeight, baton->claheMaxSlope);
+      }
+
       // Apply bitwise boolean operation between images
       if (baton->boolean != nullptr) {
         VImage booleanImage;
@@ -1330,6 +1336,9 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->linearB = sharp::AttrAsDouble(options, "linearB");
   baton->greyscale = sharp::AttrAsBool(options, "greyscale");
   baton->normalise = sharp::AttrAsBool(options, "normalise");
+  baton->claheWidth = sharp::AttrAsUint32(options, "claheWidth");
+  baton->claheHeight = sharp::AttrAsUint32(options, "claheHeight");
+  baton->claheMaxSlope = sharp::AttrAsUint32(options, "claheMaxSlope");
   baton->useExifOrientation = sharp::AttrAsBool(options, "useExifOrientation");
   baton->angle = sharp::AttrAsInt32(options, "angle");
   baton->rotationAngle = sharp::AttrAsDouble(options, "rotationAngle");

src/pipeline.h

@@ -109,6 +109,9 @@ struct PipelineBaton {
   double gammaOut;
   bool greyscale;
   bool normalise;
+  int claheWidth;
+  int claheHeight;
+  int claheMaxSlope;
   bool useExifOrientation;
   int angle;
   double rotationAngle;
@@ -234,6 +237,9 @@ struct PipelineBaton {
     gamma(0.0),
     greyscale(false),
     normalise(false),
+    claheWidth(0),
+    claheHeight(0),
+    claheMaxSlope(3),
     useExifOrientation(false),
     angle(0),
     rotationAngle(0.0),

test/fixtures/index.js

@@ -121,6 +121,8 @@ module.exports = {
 
   inputV: getPath('vfile.v'),
 
+  inputJpgClahe: getPath('concert.jpg'), // public domain - https://www.flickr.com/photos/mars_/14389236779/
+
   testPattern: getPath('test-pattern.png'),
 
   // Path for tests requiring human inspection

test/unit/clahe.js

@@ -0,0 +1,139 @@
+'use strict';
+
+const assert = require('assert');
+
+const sharp = require('../../lib');
+const fixtures = require('../fixtures');
+
+describe('Clahe', function () {
+  it('width 5 width 5 maxSlope 0', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 5, height: 5, maxSlope: 0 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-5-5-0.jpg'), data, { threshold: 10 }, done);
+      });
+  });
+
+  it('width 5 width 5 maxSlope 5', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 5, height: 5, maxSlope: 5 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-5-5-5.jpg'), data, done);
+      });
+  });
+
+  it('width 11 width 25 maxSlope 14', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 11, height: 25, maxSlope: 14 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-11-25-14.jpg'), data, done);
+      });
+  });
+
+  it('width 50 width 50 maxSlope 0', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 50, height: 50, maxSlope: 0 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-50-50-0.jpg'), data, done);
+      });
+  });
+
+  it('width 50 width 50 maxSlope 14', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 50, height: 50, maxSlope: 14 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-50-50-14.jpg'), data, done);
+      });
+  });
+
+  it('width 100 width 50 maxSlope 3', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 100, height: 50, maxSlope: 3 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-100-50-3.jpg'), data, done);
+      });
+  });
+
+  it('width 100 width 100 maxSlope 0', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 100, height: 100, maxSlope: 0 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-100-100-0.jpg'), data, done);
+      });
+  });
+
+  it('invalid maxSlope', function () {
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 100, maxSlope: -5 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 100, maxSlope: 110 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 100, maxSlope: 5.5 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 100, maxSlope: 'a string' });
+    });
+  });
+
+  it('invalid width', function () {
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100.5, height: 100 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: -5, height: 100 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: true, height: 100 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 'string test', height: 100 });
+    });
+  });
+
+  it('invalid height', function () {
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 100.5 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: -5 });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: true });
+    });
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe({ width: 100, height: 'string test' });
+    });
+  });
+
+  it('invalid options object', function () {
+    assert.throws(function () {
+      sharp(fixtures.inputJpgClahe).clahe(100, 100, 5);
+    });
+  });
+
+  it('uses default maxSlope of 3', function (done) {
+    sharp(fixtures.inputJpgClahe)
+      .clahe({ width: 100, height: 50 })
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual('jpeg', info.format);
+        fixtures.assertSimilar(fixtures.expected('clahe-100-50-3.jpg'), data, done);
+      });
+  });
+});