Release v0.20.6

Changelog, credit and doc refresh for #1342
Expose depth option for tile-based output (#1342 )
2026-02-04 13:46:19 +01:00 · 2018-08-20 11:40:10 +01:00 · 2018-08-19 10:43:25 +01:00 · 2018-08-18 15:09:53 +01:00 · 2018-08-12 20:22:39 +01:00 · 2018-08-08 08:42:18 +01:00
36 changed files with 922 additions and 800 deletions
--- a/.npmignore
+++ b/.npmignore
@@ -8,6 +8,7 @@ test
 .travis.yml
 appveyor.yml
 mkdocs.yml
+docs/css/
 vendor
 .prebuildrc
 .nyc_output
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@ sharp('input.jpg')
 ```

 ```javascript
-const roundedCorners = new Buffer(
+const roundedCorners = Buffer.from(
  '<svg><rect x="0" y="0" width="200" height="200" rx="50" ry="50"/></svg>'
 );

--- a/docs/api-channel.md
+++ b/docs/api-channel.md
@@ -1,15 +1,20 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
+## removeAlpha

-   [extractChannel][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-   [joinChannel][4]
-    -   [Parameters][5]
-   [bandbool][6]
-    -   [Parameters][7]
-    -   [Examples][8]
+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

@@ -17,7 +22,7 @@ Extract a single channel from a multi-channel image.

 ### Parameters

-   `channel` **([Number][9] \| [String][10])** zero-indexed band number to extract, or `red`, `green` or `blue` as alternative to `0`, `1` or `2` respectively.
+-   `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

@@ -30,7 +35,7 @@ sharp(input)
   });
 ```

-   Throws **[Error][11]** Invalid channel
+-   Throws **[Error][3]** Invalid channel

 Returns **Sharp** 

@@ -49,11 +54,11 @@ For raw pixel input, the `options` object should contain a `raw` attribute, whic

 ### Parameters

-   `images` **([Array][12]&lt;([String][10] \| [Buffer][13])> | [String][10] \| [Buffer][13])** one or more images (file paths, Buffers).
-   `options` **[Object][14]** image options, see `sharp()` constructor.
+-   `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][11]** Invalid parameters
+-   Throws **[Error][3]** Invalid parameters

 Returns **Sharp** 

@@ -63,7 +68,7 @@ Perform a bitwise boolean operation on all input image channels (bands) to produ

 ### Parameters

-   `boolOp` **[String][10]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+-   `boolOp` **[String][2]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.

 ### Examples

@@ -77,34 +82,18 @@ sharp('3-channel-rgb-input.png')
  });
 ```

-   Throws **[Error][11]** Invalid parameters
+-   Throws **[Error][3]** Invalid parameters

 Returns **Sharp** 

-[1]: #extractchannel
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[3]: #examples
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[4]: #joinchannel
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

-[5]: #parameters-1
+[5]: https://nodejs.org/api/buffer.html

-[6]: #bandbool
-
-[7]: #parameters-2
-
-[8]: #examples-1
-
-[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
-
-[11]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[12]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
-
-[13]: https://nodejs.org/api/buffer.html
-
-[14]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
--- a/docs/api-colour.md
+++ b/docs/api-colour.md
@@ -1,20 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [background][1]
-    -   [Parameters][2]
-   [tint][3]
-    -   [Parameters][4]
-   [greyscale][5]
-    -   [Parameters][6]
-   [grayscale][7]
-    -   [Parameters][8]
-   [toColourspace][9]
-    -   [Parameters][10]
-   [toColorspace][11]
-    -   [Parameters][12]
-
 ## background

 Set the background for the `embed`, `flatten` and `extend` operations.
@@ -26,10 +11,10 @@ The alpha value is a float between `0` (transparent) and `1` (opaque).

 ### Parameters

-   `rgba` **([String][13] \| [Object][14])** parsed by the [color][15] module to extract values for red, green, blue and alpha.
+-   `rgba` **([String][1] \| [Object][2])** parsed by the [color][3] module to extract values for red, green, blue and alpha.


-   Throws **[Error][16]** Invalid parameter
+-   Throws **[Error][4]** Invalid parameter

 Returns **Sharp** 

@@ -40,10 +25,10 @@ An alpha channel may be present and will be unchanged by the operation.

 ### Parameters

-   `rgb` **([String][13] \| [Object][14])** parsed by the [color][15] module to extract chroma values.
+-   `rgb` **([String][1] \| [Object][2])** parsed by the [color][3] module to extract chroma values.


-   Throws **[Error][16]** Invalid parameter
+-   Throws **[Error][4]** Invalid parameter

 Returns **Sharp** 

@@ -58,7 +43,7 @@ An alpha channel may be present, and will be unchanged by the operation.

 ### Parameters

-   `greyscale` **[Boolean][17]**  (optional, default `true`)
+-   `greyscale` **[Boolean][5]**  (optional, default `true`)

 Returns **Sharp** 

@@ -68,7 +53,7 @@ Alternative spelling of `greyscale`.

 ### Parameters

-   `grayscale` **[Boolean][17]**  (optional, default `true`)
+-   `grayscale` **[Boolean][5]**  (optional, default `true`)

 Returns **Sharp** 

@@ -79,10 +64,10 @@ By default output image will be web-friendly sRGB, with additional channels inte

 ### Parameters

-   `colourspace` **[String][13]?** output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][18]
+-   `colourspace` **[String][1]?** output colourspace e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...][6]


-   Throws **[Error][16]** Invalid parameters
+-   Throws **[Error][4]** Invalid parameters

 Returns **Sharp** 

@@ -92,45 +77,21 @@ Alternative spelling of `toColourspace`.

 ### Parameters

-   `colorspace` **[String][13]?** output colorspace.
+-   `colorspace` **[String][1]?** output colorspace.


-   Throws **[Error][16]** Invalid parameters
+-   Throws **[Error][4]** Invalid parameters

 Returns **Sharp** 

-[1]: #background
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[3]: #tint
+[3]: https://www.npmjs.org/package/color

-[4]: #parameters-1
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[5]: #greyscale
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[6]: #parameters-2
-
-[7]: #grayscale
-
-[8]: #parameters-3
-
-[9]: #tocolourspace
-
-[10]: #parameters-4
-
-[11]: #tocolorspace
-
-[12]: #parameters-5
-
-[13]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
-
-[14]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[15]: https://www.npmjs.org/package/color
-
-[16]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[17]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[18]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568
+[6]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L568
--- a/docs/api-composite.md
+++ b/docs/api-composite.md
@@ -1,11 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [overlayWith][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-
 ## overlayWith

 Overlay (composite) an image over the processed (resized, extracted etc.) image.
@@ -17,23 +11,23 @@ If the overlay image contains an alpha channel then composition with premultipli

 ### Parameters

-   `overlay` **([Buffer][4] \| [String][5])** Buffer containing image data or String containing the path to an image file.
-   `options` **[Object][6]?** 
-    -   `options.gravity` **[String][5]** gravity at which to place the overlay. (optional, default `'centre'`)
-    -   `options.top` **[Number][7]?** the pixel offset from the top edge.
-    -   `options.left` **[Number][7]?** the pixel offset from the left edge.
-    -   `options.tile` **[Boolean][8]** set to true to repeat the overlay image across the entire image with the given `gravity`. (optional, default `false`)
-    -   `options.cutout` **[Boolean][8]** 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][7]** integral number representing the DPI for vector overlay image. (optional, default `72`)
-    -   `options.raw` **[Object][6]?** describes overlay when using raw pixel data.
-        -   `options.raw.width` **[Number][7]?** 
-        -   `options.raw.height` **[Number][7]?** 
-        -   `options.raw.channels` **[Number][7]?** 
-    -   `options.create` **[Object][6]?** describes a blank overlay to be created.
-        -   `options.create.width` **[Number][7]?** 
-        -   `options.create.height` **[Number][7]?** 
-        -   `options.create.channels` **[Number][7]?** 3-4
-        -   `options.create.background` **([String][5] \| [Object][6])?** parsed by the [color][9] module to extract values for red, green, blue and alpha.
+-   `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]** integral 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

@@ -46,8 +40,7 @@ sharp('input.png')
  .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
  .sharpen()
  .withMetadata()
-  .quality(90)
-  .webp()
+  .webp( { quality: 90 } )
  .toBuffer()
  .then(function(outputBuffer) {
    // outputBuffer contains upside down, 300px wide, alpha channel flattened
@@ -56,26 +49,20 @@ sharp('input.png')
  });
 ```

-   Throws **[Error][10]** Invalid parameters
+-   Throws **[Error][7]** Invalid parameters

 Returns **Sharp** 

-[1]: #overlaywith
+[1]: https://nodejs.org/api/buffer.html

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[3]: #examples
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[4]: https://nodejs.org/api/buffer.html
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
+[6]: https://www.npmjs.org/package/color

-[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[9]: https://www.npmjs.org/package/color
-
-[10]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
--- a/docs/api-constructor.md
+++ b/docs/api-constructor.md
@@ -1,40 +1,28 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [Sharp][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-    -   [format][4]
-        -   [Examples][5]
-    -   [versions][6]
-        -   [Examples][7]
-   [queue][8]
-    -   [Examples][9]
-
 ## Sharp

 ### Parameters

-   `input` **([Buffer][10] \| [String][11])?** if present, can be
+-   `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][12]?** if present, is an Object with optional attributes.
-    -   `options.failOnError` **[Boolean][13]** by default apply a "best effort"
+-   `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][14]** integral number representing the DPI for vector images. (optional, default `72`)
-    -   `options.page` **[Number][14]** page number to extract for multi-page input (GIF, TIFF) (optional, default `0`)
-    -   `options.raw` **[Object][12]?** describes raw pixel input image data. See `raw()` for pixel ordering.
-        -   `options.raw.width` **[Number][14]?** 
-        -   `options.raw.height` **[Number][14]?** 
-        -   `options.raw.channels` **[Number][14]?** 1-4
-    -   `options.create` **[Object][12]?** describes a new image to be created.
-        -   `options.create.width` **[Number][14]?** 
-        -   `options.create.height` **[Number][14]?** 
-        -   `options.create.channels` **[Number][14]?** 3-4
-        -   `options.create.background` **([String][11] \| [Object][12])?** parsed by the [color][15] module to extract values for red, green, blue and alpha.
+    -   `options.density` **[Number][5]** integral 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

@@ -67,7 +55,7 @@ sharp({
    width: 300,
    height: 200,
    channels: 4,
-    background: { r: 255, g: 0, b: 0, alpha: 128 }
+    background: { r: 255, g: 0, b: 0, alpha: 0.5 }
  }
 })
 .png()
@@ -75,9 +63,9 @@ sharp({
 .then( ... );
 ```

-   Throws **[Error][16]** Invalid parameters
+-   Throws **[Error][7]** Invalid parameters

-Returns **[Sharp][17]** 
+Returns **[Sharp][8]** 

 ### format

@@ -89,7 +77,7 @@ An Object containing nested boolean values representing the available input and
 console.log(sharp.format);
 ```

-Returns **[Object][12]** 
+Returns **[Object][3]** 

 ### versions

@@ -116,36 +104,18 @@ sharp.queue.on('change', function(queueLength) {
 });
 ```

-[1]: #sharp
+[1]: https://nodejs.org/api/buffer.html

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[3]: #examples
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[4]: #format
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[5]: #examples-1
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[6]: #versions
+[6]: https://www.npmjs.org/package/color

-[7]: #examples-2
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[8]: #queue
-
-[9]: #examples-3
-
-[10]: https://nodejs.org/api/buffer.html
-
-[11]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
-
-[12]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[13]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[14]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[15]: https://www.npmjs.org/package/color
-
-[16]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[17]: #sharp
+[8]: #sharp
--- a/docs/api-input.md
+++ b/docs/api-input.md
@@ -1,20 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [clone][1]
-    -   [Examples][2]
-   [metadata][3]
-    -   [Parameters][4]
-    -   [Examples][5]
-   [stats][6]
-    -   [Parameters][7]
-    -   [Examples][8]
-   [limitInputPixels][9]
-    -   [Parameters][10]
-   [sequentialRead][11]
-    -   [Parameters][12]
-
 ## clone

 Take a "snapshot" of the Sharp instance, returning a new instance.
@@ -42,21 +27,21 @@ A Promises/A+ promise is returned when `callback` is not provided.
 -   `format`: Name of decoder used to decompress image data e.g. `jpeg`, `png`, `webp`, `gif`, `svg`
 -   `width`: Number of pixels wide (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` [...][13]
+-   `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` [...][14]
+-   `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...][2]
 -   `density`: Number of pixels per inch (DPI), if present
 -   `hasProfile`: Boolean indicating the presence of an embedded ICC profile
 -   `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
 -   `orientation`: Number value of the EXIF Orientation header, if present
 -   `exif`: Buffer containing raw EXIF data, if present
-   `icc`: Buffer containing raw [ICC][15] profile 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][16]?** called with the arguments `(err, metadata)`
+-   `callback` **[Function][4]?** called with the arguments `(err, metadata)`

 ### Examples

@@ -75,7 +60,7 @@ image
  });
 ```

-Returns **([Promise][17]&lt;[Object][18]> | Sharp)** 
+Returns **([Promise][5]&lt;[Object][6]> | Sharp)** 

 ## stats

@@ -94,10 +79,11 @@ A Promise is returned when `callback` is not provided.
    -   `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][16]?** called with the arguments `(err, stats)`
+-   `callback` **[Function][4]?** called with the arguments `(err, stats)`

 ### Examples

@@ -110,7 +96,7 @@ image
  });
 ```

-Returns **[Promise][17]&lt;[Object][18]>** 
+Returns **[Promise][5]&lt;[Object][6]>** 

 ## limitInputPixels

@@ -120,10 +106,10 @@ The default limit is 268402689 (0x3FFF _ 0x3FFF) pixels.

 ### Parameters

-   `limit` **([Number][19] \| [Boolean][20])** an integral Number of pixels, zero or false to remove limit, true to use default limit.
+-   `limit` **([Number][7] \| [Boolean][8])** an integral Number of pixels, zero or false to remove limit, true to use default limit.


-   Throws **[Error][21]** Invalid limit
+-   Throws **[Error][9]** Invalid limit

 Returns **Sharp** 

@@ -136,48 +122,24 @@ The default behaviour _before_ function call is `false`, meaning the libvips acc

 ### Parameters

-   `sequentialRead` **[Boolean][20]**  (optional, default `true`)
+-   `sequentialRead` **[Boolean][8]**  (optional, default `true`)

 Returns **Sharp** 

-[1]: #clone
+[1]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636

-[2]: #examples
+[2]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672

-[3]: #metadata
+[3]: https://www.npmjs.com/package/icc

-[4]: #parameters
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

-[5]: #examples-1
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise

-[6]: #stats
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[7]: #parameters-1
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[8]: #examples-2
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[9]: #limitinputpixels
-
-[10]: #parameters-2
-
-[11]: #sequentialread
-
-[12]: #parameters-3
-
-[13]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L636
-
-[14]: https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/enumtypes.c#L672
-
-[15]: https://www.npmjs.com/package/icc
-
-[16]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
-
-[17]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
-
-[18]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[19]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[20]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[21]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
+[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
--- a/docs/api-operation.md
+++ b/docs/api-operation.md
@@ -1,48 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [rotate][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-   [extract][4]
-    -   [Parameters][5]
-    -   [Examples][6]
-   [flip][7]
-    -   [Parameters][8]
-   [flop][9]
-    -   [Parameters][10]
-   [sharpen][11]
-    -   [Parameters][12]
-   [median][13]
-    -   [Parameters][14]
-   [blur][15]
-    -   [Parameters][16]
-   [extend][17]
-    -   [Parameters][18]
-    -   [Examples][19]
-   [flatten][20]
-    -   [Parameters][21]
-   [trim][22]
-    -   [Parameters][23]
-   [gamma][24]
-    -   [Parameters][25]
-   [negate][26]
-    -   [Parameters][27]
-   [normalise][28]
-    -   [Parameters][29]
-   [normalize][30]
-    -   [Parameters][31]
-   [convolve][32]
-    -   [Parameters][33]
-    -   [Examples][34]
-   [threshold][35]
-    -   [Parameters][36]
-   [boolean][37]
-    -   [Parameters][38]
-   [linear][39]
-    -   [Parameters][40]
-
 ## rotate

 Rotate the output image by either an explicit angle
@@ -61,7 +18,7 @@ for example `rotate(x).extract(y)` will produce a different result to `extract(y

 ### Parameters

-   `angle` **[Number][41]** angle of rotation, must be a multiple of 90. (optional, default `auto`)
+-   `angle` **[Number][1]** angle of rotation, must be a multiple of 90. (optional, default `auto`)

 ### Examples

@@ -77,7 +34,7 @@ const pipeline = sharp()
 readableStream.pipe(pipeline);
 ```

-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -91,11 +48,11 @@ Extract a region of the image.

 ### Parameters

-   `options` **[Object][43]** 
-    -   `options.left` **[Number][41]** zero-indexed offset from left edge
-    -   `options.top` **[Number][41]** zero-indexed offset from top edge
-    -   `options.width` **[Number][41]** dimension of extracted image
-    -   `options.height` **[Number][41]** dimension of extracted image
+-   `options` **[Object][3]** 
+    -   `options.left` **[Number][1]** zero-indexed offset from left edge
+    -   `options.top` **[Number][1]** zero-indexed offset from top edge
+    -   `options.width` **[Number][1]** dimension of extracted image
+    -   `options.height` **[Number][1]** dimension of extracted image

 ### Examples

@@ -117,7 +74,7 @@ sharp(input)
  });
 ```

-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -128,7 +85,7 @@ The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.

 ### Parameters

-   `flip` **[Boolean][44]**  (optional, default `true`)
+-   `flip` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -139,7 +96,7 @@ The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.

 ### Parameters

-   `flop` **[Boolean][44]**  (optional, default `true`)
+-   `flop` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -152,12 +109,12 @@ Separate control over the level of sharpening in "flat" and "jagged" areas is av

 ### Parameters

-   `sigma` **[Number][41]?** the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
-   `flat` **[Number][41]** the level of sharpening to apply to "flat" areas. (optional, default `1.0`)
-   `jagged` **[Number][41]** the level of sharpening to apply to "jagged" areas. (optional, default `2.0`)
+-   `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][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -168,10 +125,10 @@ When used without parameters the default window is 3x3.

 ### Parameters

-   `size` **[Number][41]** square mask size: size x size (optional, default `3`)
+-   `size` **[Number][1]** square mask size: size x size (optional, default `3`)


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -183,10 +140,10 @@ When a `sigma` is provided, performs a slower, more accurate Gaussian blur.

 ### Parameters

-   `sigma` **[Number][41]?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.
+-   `sigma` **[Number][1]?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -197,11 +154,11 @@ This operation will always occur after resizing and extraction, if any.

 ### Parameters

-   `extend` **([Number][41] \| [Object][43])** single pixel count to add to all edges or an Object with per-edge counts
-    -   `extend.top` **[Number][41]?** 
-    -   `extend.left` **[Number][41]?** 
-    -   `extend.bottom` **[Number][41]?** 
-    -   `extend.right` **[Number][41]?** 
+-   `extend` **([Number][1] \| [Object][3])** single pixel count to add to all edges or an Object with per-edge counts
+    -   `extend.top` **[Number][1]?** 
+    -   `extend.left` **[Number][1]?** 
+    -   `extend.bottom` **[Number][1]?** 
+    -   `extend.right` **[Number][1]?** 

 ### Examples

@@ -215,7 +172,7 @@ sharp(input)
  ...
 ```

-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -225,7 +182,7 @@ Merge alpha transparency channel, if any, with `background`.

 ### Parameters

-   `flatten` **[Boolean][44]**  (optional, default `true`)
+-   `flatten` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -235,10 +192,10 @@ Trim "boring" pixels from all edges that contain values within a percentage simi

 ### Parameters

-   `tolerance` **[Number][41]** value between 1 and 99 representing the percentage similarity. (optional, default `10`)
+-   `tolerance` **[Number][1]** value between 1 and 99 representing the percentage similarity. (optional, default `10`)


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -252,10 +209,10 @@ when applying a gamma correction.

 ### Parameters

-   `gamma` **[Number][41]** value between 1.0 and 3.0. (optional, default `2.2`)
+-   `gamma` **[Number][1]** value between 1.0 and 3.0. (optional, default `2.2`)


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -265,7 +222,7 @@ Produce the "negative" of the image.

 ### Parameters

-   `negate` **[Boolean][44]**  (optional, default `true`)
+-   `negate` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -275,7 +232,7 @@ Enhance output image contrast by stretching its luminance to cover the full dyna

 ### Parameters

-   `normalise` **[Boolean][44]**  (optional, default `true`)
+-   `normalise` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -285,7 +242,7 @@ Alternative spelling of normalise.

 ### Parameters

-   `normalize` **[Boolean][44]**  (optional, default `true`)
+-   `normalize` **[Boolean][4]**  (optional, default `true`)

 Returns **Sharp** 

@@ -295,12 +252,12 @@ Convolve the image with the specified kernel.

 ### Parameters

-   `kernel` **[Object][43]** 
-    -   `kernel.width` **[Number][41]** width of the kernel in pixels.
-    -   `kernel.height` **[Number][41]** width of the kernel in pixels.
-    -   `kernel.kernel` **[Array][45]&lt;[Number][41]>** Array of length `width*height` containing the kernel values.
-    -   `kernel.scale` **[Number][41]** the scale of the kernel in pixels. (optional, default `sum`)
-    -   `kernel.offset` **[Number][41]** the offset of the kernel in pixels. (optional, default `0`)
+-   `kernel` **[Object][3]** 
+    -   `kernel.width` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.height` **[Number][1]** width of the kernel in pixels.
+    -   `kernel.kernel` **[Array][5]&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

@@ -318,7 +275,7 @@ sharp(input)
  });
 ```

-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -328,13 +285,13 @@ Any pixel value greather than or equal to the threshold value will be set to 255

 ### Parameters

-   `threshold` **[Number][41]** a value in the range 0-255 representing the level at which the threshold will be applied. (optional, default `128`)
-   `options` **[Object][43]?** 
-    -   `options.greyscale` **[Boolean][44]** convert to single channel greyscale. (optional, default `true`)
-    -   `options.grayscale` **[Boolean][44]** alternative spelling for greyscale. (optional, default `true`)
+-   `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][3]?** 
+    -   `options.greyscale` **[Boolean][4]** convert to single channel greyscale. (optional, default `true`)
+    -   `options.grayscale` **[Boolean][4]** alternative spelling for greyscale. (optional, default `true`)


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -347,16 +304,16 @@ the selected bitwise boolean `operation` between the corresponding pixels of the

 ### Parameters

-   `operand` **([Buffer][46] \| [String][47])** Buffer containing image data or String containing the path to an image file.
-   `operator` **[String][47]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
-   `options` **[Object][43]?** 
-    -   `options.raw` **[Object][43]?** describes operand when using raw pixel data.
-        -   `options.raw.width` **[Number][41]?** 
-        -   `options.raw.height` **[Number][41]?** 
-        -   `options.raw.channels` **[Number][41]?** 
+-   `operand` **([Buffer][6] \| [String][7])** Buffer containing image data or String containing the path to an image file.
+-   `operator` **[String][7]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
+-   `options` **[Object][3]?** 
+    -   `options.raw` **[Object][3]?** describes operand when using raw pixel data.
+        -   `options.raw.width` **[Number][1]?** 
+        -   `options.raw.height` **[Number][1]?** 
+        -   `options.raw.channels` **[Number][1]?** 


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

@@ -366,104 +323,24 @@ Apply the linear formula a \* input + b to the image (levels adjustment)

 ### Parameters

-   `a` **[Number][41]** multiplier (optional, default `1.0`)
-   `b` **[Number][41]** offset (optional, default `0.0`)
+-   `a` **[Number][1]** multiplier (optional, default `1.0`)
+-   `b` **[Number][1]** offset (optional, default `0.0`)


-   Throws **[Error][42]** Invalid parameters
+-   Throws **[Error][2]** Invalid parameters

 Returns **Sharp** 

-[1]: #rotate
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[3]: #examples
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[4]: #extract
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[5]: #parameters-1
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

-[6]: #examples-1
+[6]: https://nodejs.org/api/buffer.html

-[7]: #flip
-
-[8]: #parameters-2
-
-[9]: #flop
-
-[10]: #parameters-3
-
-[11]: #sharpen
-
-[12]: #parameters-4
-
-[13]: #median
-
-[14]: #parameters-5
-
-[15]: #blur
-
-[16]: #parameters-6
-
-[17]: #extend
-
-[18]: #parameters-7
-
-[19]: #examples-2
-
-[20]: #flatten
-
-[21]: #parameters-8
-
-[22]: #trim
-
-[23]: #parameters-9
-
-[24]: #gamma
-
-[25]: #parameters-10
-
-[26]: #negate
-
-[27]: #parameters-11
-
-[28]: #normalise
-
-[29]: #parameters-12
-
-[30]: #normalize
-
-[31]: #parameters-13
-
-[32]: #convolve
-
-[33]: #parameters-14
-
-[34]: #examples-3
-
-[35]: #threshold
-
-[36]: #parameters-15
-
-[37]: #boolean
-
-[38]: #parameters-16
-
-[39]: #linear
-
-[40]: #parameters-17
-
-[41]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[42]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[43]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[44]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[45]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
-
-[46]: https://nodejs.org/api/buffer.html
-
-[47]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
--- a/docs/api-output.md
+++ b/docs/api-output.md
@@ -1,37 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [toFile][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-   [toBuffer][4]
-    -   [Parameters][5]
-    -   [Examples][6]
-   [withMetadata][7]
-    -   [Parameters][8]
-    -   [Examples][9]
-   [jpeg][10]
-    -   [Parameters][11]
-    -   [Examples][12]
-   [png][13]
-    -   [Parameters][14]
-    -   [Examples][15]
-   [webp][16]
-    -   [Parameters][17]
-    -   [Examples][18]
-   [tiff][19]
-    -   [Parameters][20]
-    -   [Examples][21]
-   [raw][22]
-    -   [Examples][23]
-   [toFormat][24]
-    -   [Parameters][25]
-    -   [Examples][26]
-   [tile][27]
-    -   [Parameters][28]
-    -   [Examples][29]
-
 ## toFile

 Write output image data to a file.
@@ -44,8 +12,8 @@ A `Promise` is returned when `callback` is not provided.

 ### Parameters

-   `fileOut` **[String][30]** the path to write the image data to.
-   `callback` **[Function][31]?** called on completion with two arguments `(err, info)`.
+-   `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`.
@@ -64,9 +32,9 @@ sharp(input)
  .catch(err => { ... });
 ```

-   Throws **[Error][32]** Invalid parameters
+-   Throws **[Error][3]** Invalid parameters

-Returns **[Promise][33]&lt;[Object][34]>** when no callback is provided
+Returns **[Promise][4]&lt;[Object][5]>** when no callback is provided

 ## toBuffer

@@ -86,9 +54,9 @@ A `Promise` is returned when `callback` is not provided.

 ### Parameters

-   `options` **[Object][34]?** 
-    -   `options.resolveWithObject` **[Boolean][35]?** Resolve the Promise with an Object containing `data` and `info` properties instead of resolving only with `data`.
-   `callback` **[Function][31]?** 
+-   `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

@@ -111,7 +79,7 @@ sharp(input)
  .catch(err => { ... });
 ```

-Returns **[Promise][33]&lt;[Buffer][36]>** when no callback is provided
+Returns **[Promise][4]&lt;[Buffer][7]>** when no callback is provided

 ## withMetadata

@@ -121,8 +89,8 @@ This will also convert to and add a web-friendly sRGB ICC profile.

 ### Parameters

-   `withMetadata` **[Object][34]?** 
-    -   `withMetadata.orientation` **[Number][37]?** value between 1 and 8, used to update the EXIF `Orientation` tag.
+-   `withMetadata` **[Object][5]?** 
+    -   `withMetadata.orientation` **[Number][8]?** value between 1 and 8, used to update the EXIF `Orientation` tag.

 ### Examples

@@ -133,7 +101,7 @@ sharp('input.jpg')
  .then(info => { ... });
 ```

-   Throws **[Error][32]** Invalid parameters
+-   Throws **[Error][3]** Invalid parameters

 Returns **Sharp** 

@@ -143,15 +111,19 @@ Use these JPEG options for output image.

 ### Parameters

-   `options` **[Object][34]?** output options
-    -   `options.quality` **[Number][37]** quality, integer 1-100 (optional, default `80`)
-    -   `options.progressive` **[Boolean][35]** use progressive (interlace) scan (optional, default `false`)
-    -   `options.chromaSubsampling` **[String][30]** set to '4:4:4' to prevent chroma subsampling when quality &lt;= 90 (optional, default `'4:2:0'`)
-    -   `options.trellisQuantisation` **[Boolean][35]** apply trellis quantisation, requires mozjpeg (optional, default `false`)
-    -   `options.overshootDeringing` **[Boolean][35]** apply overshoot deringing, requires mozjpeg (optional, default `false`)
-    -   `options.optimiseScans` **[Boolean][35]** optimise progressive scans, forces progressive, requires mozjpeg (optional, default `false`)
-    -   `options.optimizeScans` **[Boolean][35]** alternative spelling of optimiseScans (optional, default `false`)
-    -   `options.force` **[Boolean][35]** force JPEG output, otherwise attempt to use input format (optional, default `true`)
+-   `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

@@ -165,7 +137,7 @@ const data = await sharp(input)
  .toBuffer();
 ```

-   Throws **[Error][32]** Invalid options
+-   Throws **[Error][3]** Invalid options

 Returns **Sharp** 

@@ -178,11 +150,11 @@ Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.

 ### Parameters

-   `options` **[Object][34]?** 
-    -   `options.progressive` **[Boolean][35]** use progressive (interlace) scan (optional, default `false`)
-    -   `options.compressionLevel` **[Number][37]** zlib compression level, 0-9 (optional, default `9`)
-    -   `options.adaptiveFiltering` **[Boolean][35]** use adaptive row filtering (optional, default `false`)
-    -   `options.force` **[Boolean][35]** force PNG output, otherwise attempt to use input format (optional, default `true`)
+-   `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

@@ -193,7 +165,7 @@ const data = await sharp(input)
  .toBuffer();
 ```

-   Throws **[Error][32]** Invalid options
+-   Throws **[Error][3]** Invalid options

 Returns **Sharp** 

@@ -203,12 +175,12 @@ Use these WebP options for output image.

 ### Parameters

-   `options` **[Object][34]?** output options
-    -   `options.quality` **[Number][37]** quality, integer 1-100 (optional, default `80`)
-    -   `options.alphaQuality` **[Number][37]** quality of alpha layer, integer 0-100 (optional, default `100`)
-    -   `options.lossless` **[Boolean][35]** use lossless compression mode (optional, default `false`)
-    -   `options.nearLossless` **[Boolean][35]** use near_lossless compression mode (optional, default `false`)
-    -   `options.force` **[Boolean][35]** force WebP output, otherwise attempt to use input format (optional, default `true`)
+-   `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

@@ -219,7 +191,7 @@ const data = await sharp(input)
  .toBuffer();
 ```

-   Throws **[Error][32]** Invalid options
+-   Throws **[Error][3]** Invalid options

 Returns **Sharp** 

@@ -229,14 +201,14 @@ Use these TIFF options for output image.

 ### Parameters

-   `options` **[Object][34]?** output options
-    -   `options.quality` **[Number][37]** quality, integer 1-100 (optional, default `80`)
-    -   `options.force` **[Boolean][35]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
-    -   `options.compression` **[Boolean][35]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
-    -   `options.predictor` **[Boolean][35]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
-    -   `options.xres` **[Number][37]** horizontal resolution in pixels/mm (optional, default `1.0`)
-    -   `options.yres` **[Number][37]** vertical resolution in pixels/mm (optional, default `1.0`)
-    -   `options.squash` **[Boolean][35]** squash 8-bit images down to 1 bit (optional, default `false`)
+-   `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

@@ -251,7 +223,7 @@ sharp('input.svg')
  .then(info => { ... });
 ```

-   Throws **[Error][32]** Invalid options
+-   Throws **[Error][3]** Invalid options

 Returns **Sharp** 

@@ -276,8 +248,8 @@ Force output to a given format.

 ### Parameters

-   `format` **([String][30] \| [Object][34])** as a String or an Object with an 'id' attribute
-   `options` **[Object][34]** output options
+-   `format` **([String][1] \| [Object][5])** as a String or an Object with an 'id' attribute
+-   `options` **[Object][5]** output options

 ### Examples

@@ -288,7 +260,7 @@ const data = await sharp(input)
  .toBuffer();
 ```

-   Throws **[Error][32]** unsupported format or options
+-   Throws **[Error][3]** unsupported format or options

 Returns **Sharp** 

@@ -302,12 +274,13 @@ Warning: multiple sharp instances concurrently producing tile output can expose

 ### Parameters

-   `tile` **[Object][34]?** 
-    -   `tile.size` **[Number][37]** tile size in pixels, a value between 1 and 8192. (optional, default `256`)
-    -   `tile.overlap` **[Number][37]** tile overlap in pixels, a value between 0 and 8192. (optional, default `0`)
-    -   `tile.angle` **[Number][37]** tile angle of rotation, must be a multiple of 90. (optional, default `0`)
-    -   `tile.container` **[String][30]** tile container, with value `fs` (filesystem) or `zip` (compressed file). (optional, default `'fs'`)
-    -   `tile.layout` **[String][30]** filesystem layout, possible values are `dz`, `zoomify` or `google`. (optional, default `'dz'`)
+-   `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

@@ -323,80 +296,22 @@ sharp('input.tiff')
  });
 ```

-   Throws **[Error][32]** Invalid parameters
+-   Throws **[Error][3]** Invalid parameters

 Returns **Sharp** 

-[1]: #tofile
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

-[3]: #examples
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[4]: #tobuffer
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise

-[5]: #parameters-1
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[6]: #examples-1
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[7]: #withmetadata
+[7]: https://nodejs.org/api/buffer.html

-[8]: #parameters-2
-
-[9]: #examples-2
-
-[10]: #jpeg
-
-[11]: #parameters-3
-
-[12]: #examples-3
-
-[13]: #png
-
-[14]: #parameters-4
-
-[15]: #examples-4
-
-[16]: #webp
-
-[17]: #parameters-5
-
-[18]: #examples-5
-
-[19]: #tiff
-
-[20]: #parameters-6
-
-[21]: #examples-6
-
-[22]: #raw
-
-[23]: #examples-7
-
-[24]: #toformat
-
-[25]: #parameters-7
-
-[26]: #examples-8
-
-[27]: #tile
-
-[28]: #parameters-8
-
-[29]: #examples-9
-
-[30]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
-
-[31]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
-
-[32]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[33]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise
-
-[34]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[35]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[36]: https://nodejs.org/api/buffer.html
-
-[37]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
--- a/docs/api-resize.md
+++ b/docs/api-resize.md
@@ -1,23 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [resize][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-   [crop][4]
-    -   [Parameters][5]
-    -   [Examples][6]
-   [embed][7]
-    -   [Parameters][8]
-    -   [Examples][9]
-   [max][10]
-    -   [Examples][11]
-   [min][12]
-   [ignoreAspectRatio][13]
-   [withoutEnlargement][14]
-    -   [Parameters][15]
-
 ## resize

 Resize image to `width` x `height`.
@@ -25,18 +7,18 @@ By default, the resized image is centre cropped to the exact size specified.

 Possible kernels are:

-   `nearest`: Use [nearest neighbour interpolation][16].
-   `cubic`: Use a [Catmull-Rom spline][17].
-   `lanczos2`: Use a [Lanczos kernel][18] with `a=2`.
+-   `nearest`: Use [nearest neighbour interpolation][1].
+-   `cubic`: Use a [Catmull-Rom spline][2].
+-   `lanczos2`: Use a [Lanczos kernel][3] with `a=2`.
 -   `lanczos3`: Use a Lanczos kernel with `a=3` (the default).

 ### Parameters

-   `width` **[Number][19]?** pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
-   `height` **[Number][19]?** pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
-   `options` **[Object][20]?** 
-    -   `options.kernel` **[String][21]** the kernel to use for image reduction. (optional, default `'lanczos3'`)
-    -   `options.fastShrinkOnLoad` **[Boolean][22]** 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`)
+-   `width` **[Number][4]?** pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
+-   `height` **[Number][4]?** pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
+-   `options` **[Object][5]?** 
+    -   `options.kernel` **[String][6]** the kernel to use for image reduction. (optional, default `'lanczos3'`)
+    -   `options.fastShrinkOnLoad` **[Boolean][7]** 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

@@ -55,7 +37,7 @@ sharp(inputBuffer)
  });
 ```

-   Throws **[Error][23]** Invalid parameters
+-   Throws **[Error][8]** Invalid parameters

 Returns **Sharp** 

@@ -69,12 +51,12 @@ Possible attributes of the optional `sharp.gravity` are `north`, `northeast`, `e
 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][24].
+-   `entropy`: focus on the region with the highest [Shannon entropy][9].
 -   `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.

 ### Parameters

-   `crop` **[String][21]** A member of `sharp.gravity` to crop to an edge/corner or `sharp.strategy` to crop dynamically. (optional, default `'centre'`)
+-   `crop` **[String][6]** A member of `sharp.gravity` to crop to an edge/corner or `sharp.strategy` to crop dynamically. (optional, default `'centre'`)

 ### Examples

@@ -90,7 +72,7 @@ const transformer = sharp()
 readableStream.pipe(transformer).pipe(writableStream);
 ```

-   Throws **[Error][23]** Invalid parameters
+-   Throws **[Error][8]** Invalid parameters

 Returns **Sharp** 

@@ -104,7 +86,7 @@ contain an alpha channel, even when the input image does not.

 ### Parameters

-   `embed` **[String][21]** A member of `sharp.gravity` to embed to an edge/corner. (optional, default `'centre'`)
+-   `embed` **[String][6]** A member of `sharp.gravity` to embed to an edge/corner. (optional, default `'centre'`)

 ### Examples

@@ -123,7 +105,7 @@ sharp('input.gif')
  });
 ```

-   Throws **[Error][23]** Invalid parameters
+-   Throws **[Error][8]** Invalid parameters

 Returns **Sharp** 

@@ -177,54 +159,24 @@ The default behaviour _before_ function call is `false`, meaning the image will

 ### Parameters

-   `withoutEnlargement` **[Boolean][22]**  (optional, default `true`)
+-   `withoutEnlargement` **[Boolean][7]**  (optional, default `true`)

 Returns **Sharp** 

-[1]: #resize
+[1]: http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation

-[2]: #parameters
+[2]: https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline

-[3]: #examples
+[3]: https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel

-[4]: #crop
+[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

-[5]: #parameters-1
+[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[6]: #examples-1
+[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

-[7]: #embed
+[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[8]: #parameters-2
+[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

-[9]: #examples-2
-
-[10]: #max
-
-[11]: #examples-3
-
-[12]: #min
-
-[13]: #ignoreaspectratio
-
-[14]: #withoutenlargement
-
-[15]: #parameters-3
-
-[16]: http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation
-
-[17]: https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
-
-[18]: https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel
-
-[19]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
-
-[20]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[21]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
-
-[22]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[23]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[24]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29
+[9]: https://en.wikipedia.org/wiki/Entropy_%28information_theory%29
--- a/docs/api-utility.md
+++ b/docs/api-utility.md
@@ -1,19 +1,5 @@
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->

-### Table of Contents
-
-   [cache][1]
-    -   [Parameters][2]
-    -   [Examples][3]
-   [concurrency][4]
-    -   [Parameters][5]
-    -   [Examples][6]
-   [counters][7]
-    -   [Examples][8]
-   [simd][9]
-    -   [Parameters][10]
-    -   [Examples][11]
-
 ## cache

 Gets or, when options are provided, sets the limits of _libvips'_ operation cache.
@@ -23,10 +9,10 @@ useful for determining how much working memory is required for a particular task

 ### Parameters

-   `options` **([Object][12] \| [Boolean][13])** Object with the following attributes, or Boolean where true uses default cache settings and false removes all caching (optional, default `true`)
-    -   `options.memory` **[Number][14]** is the maximum memory in MB to use for this cache (optional, default `50`)
-    -   `options.files` **[Number][14]** is the maximum number of files to hold open (optional, default `20`)
-    -   `options.items` **[Number][14]** is the maximum number of operations to cache (optional, default `100`)
+-   `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

@@ -40,7 +26,7 @@ sharp.cache( { files: 0 } );
 sharp.cache(false);
 ```

-Returns **[Object][12]** 
+Returns **[Object][1]** 

 ## concurrency

@@ -56,7 +42,7 @@ This method always returns the current concurrency.

 ### Parameters

-   `concurrency` **[Number][14]?** 
+-   `concurrency` **[Number][3]?** 

 ### Examples

@@ -66,7 +52,7 @@ sharp.concurrency(2); // 2
 sharp.concurrency(0); // 4
 ```

-Returns **[Number][14]** concurrency
+Returns **[Number][3]** concurrency

 ## counters

@@ -81,7 +67,7 @@ Provides access to internal task counters.
 const counters = sharp.counters(); // { queue: 2, process: 4 }
 ```

-Returns **[Object][12]** 
+Returns **[Object][1]** 

 ## simd

@@ -96,7 +82,7 @@ Versions of liborc prior to 0.4.25 are known to segfault under heavy load.

 ### Parameters

-   `simd` **[Boolean][13]**  (optional, default `false`)
+-   `simd` **[Boolean][2]**  (optional, default `false`)

 ### Examples

@@ -110,32 +96,10 @@ const simd = sharp.simd(true);
 // attempts to enable the use of SIMD, returning true if available
 ```

-Returns **[Boolean][13]** 
+Returns **[Boolean][2]** 

-[1]: #cache
+[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

-[2]: #parameters
+[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

-[3]: #examples
-
-[4]: #concurrency
-
-[5]: #parameters-1
-
-[6]: #examples-1
-
-[7]: #counters
-
-[8]: #examples-2
-
-[9]: #simd
-
-[10]: #parameters-2
-
-[11]: #examples-3
-
-[12]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
-[13]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-
-[14]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -4,6 +4,43 @@

 Requires libvips v8.6.1.

+#### 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.
--- a/docs/css/extra.css
+++ b/docs/css/extra.css
@@ -0,0 +1,5 @@
+/* Nest document subheadings in navigation */
+ul.subnav ul:not(.subnav) {
+  padding-left: 2em;
+  font-size: 80%;
+}
--- a/docs/index.md
+++ b/docs/index.md
@@ -112,6 +112,10 @@ the help and code contributions of the following people:
 * [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)

 Thank you!

--- a/install/libvips.js
+++ b/install/libvips.js
@@ -17,6 +17,22 @@ 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 extractTarball = function (tarPath) {
+  const vendorPath = path.join(__dirname, '..', 'vendor');
+  if (!fs.existsSync(vendorPath)) {
+    fs.mkdirSync(vendorPath);
+  }
+  tar
+    .extract({
+      file: tarPath,
+      cwd: vendorPath,
+      strict: true
+    })
+    .catch(function (err) {
+      throw err;
+    });
+};
+
 try {
  const useGlobalLibvips = libvips.useGlobalLibvips();
  if (useGlobalLibvips) {
@@ -29,11 +45,15 @@ try {
  } else {
    // Is this arch/platform supported?
    const arch = process.env.npm_config_arch || process.arch;
-    if (platform() === 'win32-ia32') {
+    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}\n`);
+      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.isNonGlibcLinux) {
      throw new Error(`Use with ${detectLibc.family} libc requires manual installation of libvips >= ${minimumLibvipsVersion}`);
@@ -42,38 +62,30 @@ try {
      throw new Error(`Use with glibc version ${detectLibc.version} requires manual installation of libvips >= ${minimumLibvipsVersion}`);
    }
    // Download to per-process temporary file
-    const tarFilename = ['libvips', minimumLibvipsVersion, platform()].join('-') + '.tar.gz';
-    const tarPathTemp = path.join(os.tmpdir(), `${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('close', function () {
-      const vendorPath = path.join(__dirname, '..', 'vendor');
-      fs.mkdirSync(vendorPath);
-      tar
-        .extract({
-          file: tarPathTemp,
-          cwd: vendorPath,
-          strict: true
-        })
-        .then(function () {
-          try {
-            fs.unlinkSync(tarPathTemp);
-          } catch (err) {}
-        })
-        .catch(function (err) {
+    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('close', function () {
+        fs.renameSync(tarPathTemp, tarPathCache);
+        extractTarball(tarPathCache);
+      });
+    }
  }
 } catch (err) {
  npmLog.error('sharp', err.message);
--- a/lib/channel.js
+++ b/lib/channel.js
@@ -12,6 +12,23 @@ const bool = {
  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.
 *
@@ -102,6 +119,7 @@ function bandbool (boolOp) {
 module.exports = function (Sharp) {
  // Public instance functions
  [
+    removeAlpha,
    extractChannel,
    joinChannel,
    bandbool
--- a/lib/composite.js
+++ b/lib/composite.js
@@ -19,8 +19,7 @@ const is = require('./is');
 *   .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
 *   .sharpen()
 *   .withMetadata()
- *   .quality(90)
- *   .webp()
+ *   .webp( { quality: 90 } )
 *   .toBuffer()
 *   .then(function(outputBuffer) {
 *     // outputBuffer contains upside down, 300px wide, alpha channel flattened
--- a/lib/constructor.js
+++ b/lib/constructor.js
@@ -81,7 +81,7 @@ const debuglog = util.debuglog('sharp');
 *     width: 300,
 *     height: 200,
 *     channels: 4,
- *     background: { r: 255, g: 0, b: 0, alpha: 128 }
+ *     background: { r: 255, g: 0, b: 0, alpha: 0.5 }
 *   }
 * })
 * .png()
@@ -171,6 +171,7 @@ const Sharp = function (input, options) {
    booleanFileIn: '',
    joinChannelIn: [],
    extractChannel: -1,
+    removeAlpha: false,
    colourspace: 'srgb',
    // overlay
    overlayGravity: 0,
@@ -192,6 +193,8 @@ const Sharp = function (input, options) {
    jpegTrellisQuantisation: false,
    jpegOvershootDeringing: false,
    jpegOptimiseScans: false,
+    jpegOptimiseCoding: true,
+    jpegQuantisationTable: 0,
    pngProgressive: false,
    pngCompressionLevel: 9,
    pngAdaptiveFiltering: false,
--- a/lib/input.js
+++ b/lib/input.js
@@ -264,6 +264,7 @@ function metadata (callback) {
 *     - `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);
--- a/lib/libvips.js
+++ b/lib/libvips.js
@@ -1,17 +1,32 @@
 '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 minimumLibvipsVersion = process.env.npm_package_config_libvips || require('../package.json').config.libvips;
+const env = process.env;
+const minimumLibvipsVersion = env.npm_package_config_libvips || require('../package.json').config.libvips;

 const spawnSyncOptions = {
  encoding: 'utf8',
  shell: true
 };

+const cachePath = function () {
+  const npmCachePath = env.npm_config_cache || (env.APPDATA ? path.join(env.APPDATA, 'npm-cache') : path.join(os.homedir(), '.npm'));
+  if (!fs.existsSync(npmCachePath)) {
+    fs.mkdirSync(npmCachePath);
+  }
+  const libvipsCachePath = path.join(npmCachePath, '_libvips');
+  if (!fs.existsSync(libvipsCachePath)) {
+    fs.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 || '';
@@ -23,21 +38,24 @@ const globalLibvipsVersion = function () {

 const hasVendoredLibvips = function () {
  const currentPlatformId = platform();
+  let vendorPlatformId;
  try {
-    const vendorPlatformId = require(path.join(__dirname, '..', 'vendor', 'platform.json'));
+    vendorPlatformId = require(path.join(__dirname, '..', 'vendor', 'platform.json'));
+  } catch (err) {}
+  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'.`);
    }
-  } catch (err) {}
+  }
  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(), process.env.PKG_CONFIG_PATH, '/usr/local/lib/pkgconfig', '/usr/lib/pkgconfig']
+    return [brewPkgConfigPath.trim(), env.PKG_CONFIG_PATH, '/usr/local/lib/pkgconfig', '/usr/lib/pkgconfig']
      .filter(function (p) { return !!p; })
      .join(':');
  } else {
@@ -46,7 +64,7 @@ const pkgConfigPath = function () {
 };

 const useGlobalLibvips = function () {
-  if (Boolean(process.env.SHARP_IGNORE_GLOBAL_LIBVIPS) === true) {
+  if (Boolean(env.SHARP_IGNORE_GLOBAL_LIBVIPS) === true) {
    return false;
  }

@@ -56,6 +74,7 @@ const useGlobalLibvips = function () {

 module.exports = {
  minimumLibvipsVersion: minimumLibvipsVersion,
+  cachePath: cachePath,
  globalLibvipsVersion: globalLibvipsVersion,
  hasVendoredLibvips: hasVendoredLibvips,
  pkgConfigPath: pkgConfigPath,
--- a/lib/output.js
+++ b/lib/output.js
@@ -148,6 +148,10 @@ function withMetadata (withMetadata) {
 * @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
@@ -185,6 +189,18 @@ function jpeg (options) {
        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);
 }
@@ -255,10 +271,10 @@ function webp (options) {
    }
  }
  if (is.object(options) && is.defined(options.alphaQuality)) {
-    if (is.integer(options.alphaQuality) && is.inRange(options.alphaQuality, 1, 100)) {
+    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, 1-100) ' + options.alphaQuality);
+      throw new Error('Invalid webp alpha quality (integer, 0-100) ' + options.alphaQuality);
    }
  }
  if (is.object(options) && is.defined(options.lossless)) {
@@ -407,6 +423,7 @@ function toFormat (format, options) {
 * @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}
@@ -458,6 +475,15 @@ function tile (tile) {
        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'])) {
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -5,6 +5,8 @@ site_description: High performance Node.js image processing, the fastest module
 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
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
  "name": "sharp",
  "description": "High performance Node.js image processing, the fastest module to resize JPEG, PNG, WebP and TIFF images",
-  "version": "0.20.4",
+  "version": "0.20.6",
  "author": "Lovell Fuller <npm@lovell.info>",
  "homepage": "https://github.com/lovell/sharp",
  "contributors": [
@@ -48,7 +48,11 @@
    "Andrea Bianco <andrea.bianco@unibas.ch>",
    "Rik Heywood <rik@rik.org>",
    "Thomas Parisot <hi@oncletom.io>",
-    "Nathan Graves <nathanrgraves+github@gmail.com>"
+    "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>"
  ],
  "scripts": {
    "install": "(node install/libvips && node install/dll-copy && prebuild-install) || (node-gyp rebuild && node install/dll-copy)",
@@ -56,7 +60,7 @@
    "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 lib/$m.js >docs/api-$m.md; done"
+    "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": {
@@ -86,21 +90,21 @@
    "fs-copy-file-sync": "^1.1.1",
    "npmlog": "^4.1.2",
    "prebuild-install": "^4.0.0",
-    "semver": "^5.5.0",
+    "semver": "^5.5.1",
    "simple-get": "^2.8.1",
-    "tar": "^4.4.4",
+    "tar": "^4.4.6",
    "tunnel-agent": "^0.6.0"
  },
  "devDependencies": {
    "async": "^2.6.1",
    "cc": "^1.0.2",
    "decompress-zip": "^0.3.1",
-    "documentation": "^8.0.0",
+    "documentation": "^8.1.1",
    "exif-reader": "^1.0.2",
    "icc": "^1.0.0",
    "mocha": "^5.2.0",
    "nyc": "^12.0.2",
-    "prebuild": "^7.6.0",
+    "prebuild": "^7.6.2",
    "prebuild-ci": "^2.2.3",
    "rimraf": "^2.6.2",
    "semistandard": "^12.0.1"
--- a/src/operations.cc
+++ b/src/operations.cc
@@ -28,6 +28,16 @@ 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
@@ -223,10 +233,8 @@ namespace sharp {
  VImage Gamma(VImage image, double const exponent) {
    if (HasAlpha(image)) {
      // Separate alpha channel
-      VImage imageWithoutAlpha = image.extract_band(0,
-        VImage::option()->set("n", image.bands() - 1));
      VImage alpha = image[image.bands() - 1];
-      return imageWithoutAlpha.gamma(VImage::option()->set("exponent", exponent)).bandjoin(alpha);
+      return RemoveAlpha(image).gamma(VImage::option()->set("exponent", exponent)).bandjoin(alpha);
    } else {
      return image.gamma(VImage::option()->set("exponent", exponent));
    }
@@ -374,10 +382,8 @@ namespace sharp {
  VImage Linear(VImage image, double const a, double const b) {
    if (HasAlpha(image)) {
      // Separate alpha channel
-      VImage imageWithoutAlpha = image.extract_band(0,
-        VImage::option()->set("n", image.bands() - 1));
      VImage alpha = image[image.bands() - 1];
-      return imageWithoutAlpha.linear(a, b).bandjoin(alpha);
+      return RemoveAlpha(image).linear(a, b).bandjoin(alpha);
    } else {
      return image.linear(a, b);
    }
--- a/src/operations.h
+++ b/src/operations.h
@@ -25,6 +25,11 @@ 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.
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -694,10 +694,19 @@ class PipelineWorker : public Nan::AsyncWorker {
          (baton->err).append("Cannot extract channel from image. Too few channels in image.");
          return Error();
        }
+        VipsInterpretation const interpretation = sharp::Is16Bit(image.interpretation())
+          ? VIPS_INTERPRETATION_GREY16
+          : VIPS_INTERPRETATION_B_W;
        image = image
          .extract_band(baton->extractChannel)
-          .copy(VImage::option()->set("interpretation", VIPS_INTERPRETATION_B_W));
+          .copy(VImage::option()->set("interpretation", interpretation));
      }
+
+      // Remove alpha channel, if any
+      if (baton->removeAlpha) {
+        image = sharp::RemoveAlpha(image);
+      }
+
      // Convert image to sRGB, if not already
      if (sharp::Is16Bit(image.interpretation())) {
        image = image.cast(VIPS_FORMAT_USHORT);
@@ -733,9 +742,10 @@ class PipelineWorker : public Nan::AsyncWorker {
            ->set("interlace", baton->jpegProgressive)
            ->set("no_subsample", baton->jpegChromaSubsampling == "4:4:4")
            ->set("trellis_quant", baton->jpegTrellisQuantisation)
+            ->set("quant_table", baton->jpegQuantisationTable)
            ->set("overshoot_deringing", baton->jpegOvershootDeringing)
            ->set("optimize_scans", baton->jpegOptimiseScans)
-            ->set("optimize_coding", TRUE)));
+            ->set("optimize_coding", baton->jpegOptimiseCoding)));
          baton->bufferOut = static_cast<char*>(area->data);
          baton->bufferOutLength = area->length;
          area->free_fn = nullptr;
@@ -848,9 +858,10 @@ class PipelineWorker : public Nan::AsyncWorker {
            ->set("interlace", baton->jpegProgressive)
            ->set("no_subsample", baton->jpegChromaSubsampling == "4:4:4")
            ->set("trellis_quant", baton->jpegTrellisQuantisation)
+            ->set("quant_table", baton->jpegQuantisationTable)
            ->set("overshoot_deringing", baton->jpegOvershootDeringing)
            ->set("optimize_scans", baton->jpegOptimiseScans)
-            ->set("optimize_coding", TRUE));
+            ->set("optimize_coding", baton->jpegOptimiseCoding));
          baton->formatOut = "jpeg";
          baton->channels = std::min(baton->channels, 3);
        } else if (baton->formatOut == "png" || (mightMatchInput && isPng) || (willMatchInput &&
@@ -927,21 +938,30 @@ class PipelineWorker : public Nan::AsyncWorker {
              {"interlace", baton->jpegProgressive ? "TRUE" : "FALSE"},
              {"no_subsample", baton->jpegChromaSubsampling == "4:4:4" ? "TRUE": "FALSE"},
              {"trellis_quant", baton->jpegTrellisQuantisation ? "TRUE" : "FALSE"},
+              {"quant_table", std::to_string(baton->jpegQuantisationTable)},
              {"overshoot_deringing", baton->jpegOvershootDeringing ? "TRUE": "FALSE"},
              {"optimize_scans", baton->jpegOptimiseScans ? "TRUE": "FALSE"},
-              {"optimize_coding", "TRUE"}
+              {"optimize_coding", baton->jpegOptimiseCoding ? "TRUE": "FALSE"}
            };
            suffix = AssembleSuffixString(extname, options);
          }
          // Write DZ to file
-          image.dzsave(const_cast<char*>(baton->fileOut.data()), VImage::option()
-            ->set("strip", !baton->withMetadata)
-            ->set("tile_size", baton->tileSize)
-            ->set("overlap", baton->tileOverlap)
-            ->set("container", baton->tileContainer)
-            ->set("layout", baton->tileLayout)
-            ->set("suffix", const_cast<char*>(suffix.data()))
-            ->set("angle", CalculateAngleRotation(baton->tileAngle)));
+          vips::VOption *options = VImage::option()
+                                       ->set("strip", !baton->withMetadata)
+                                       ->set("tile_size", baton->tileSize)
+                                       ->set("overlap", baton->tileOverlap)
+                                       ->set("container", baton->tileContainer)
+                                       ->set("layout", baton->tileLayout)
+                                       ->set("suffix", const_cast<char*>(suffix.data()))
+                                       ->set("angle", CalculateAngleRotation(baton->tileAngle));
+
+          // libvips chooses a default depth based on layout. Instead of replicating that logic here by
+          // not passing anything - libvips will handle choice
+          if (baton->tileDepth < VIPS_FOREIGN_DZ_DEPTH_LAST) {
+            options->set("depth", baton->tileDepth);
+          }
+
+          image.dzsave(const_cast<char*>(baton->fileOut.data()), options);
          baton->formatOut = "dz";
        } else if (baton->formatOut == "v" || (mightMatchInput && isV) ||
          (willMatchInput && inputImageType == ImageType::VIPS)) {
@@ -1232,6 +1252,7 @@ NAN_METHOD(pipeline) {
  baton->extendLeft = AttrTo<int32_t>(options, "extendLeft");
  baton->extendRight = AttrTo<int32_t>(options, "extendRight");
  baton->extractChannel = AttrTo<int32_t>(options, "extractChannel");
+  baton->removeAlpha = AttrTo<bool>(options, "removeAlpha");
  if (HasAttr(options, "boolean")) {
    baton->boolean = CreateInputDescriptor(AttrAs<v8::Object>(options, "boolean"), buffersToPersist);
    baton->booleanOp = sharp::GetBooleanOperation(AttrAsStr(options, "booleanOp"));
@@ -1266,8 +1287,10 @@ NAN_METHOD(pipeline) {
  baton->jpegProgressive = AttrTo<bool>(options, "jpegProgressive");
  baton->jpegChromaSubsampling = AttrAsStr(options, "jpegChromaSubsampling");
  baton->jpegTrellisQuantisation = AttrTo<bool>(options, "jpegTrellisQuantisation");
+  baton->jpegQuantisationTable = AttrTo<uint32_t>(options, "jpegQuantisationTable");
  baton->jpegOvershootDeringing = AttrTo<bool>(options, "jpegOvershootDeringing");
  baton->jpegOptimiseScans = AttrTo<bool>(options, "jpegOptimiseScans");
+  baton->jpegOptimiseCoding = AttrTo<bool>(options, "jpegOptimiseCoding");
  baton->pngProgressive = AttrTo<bool>(options, "pngProgressive");
  baton->pngCompressionLevel = AttrTo<uint32_t>(options, "pngCompressionLevel");
  baton->pngAdaptiveFiltering = AttrTo<bool>(options, "pngAdaptiveFiltering");
@@ -1306,6 +1329,17 @@ NAN_METHOD(pipeline) {
    baton->tileLayout = VIPS_FOREIGN_DZ_LAYOUT_DZ;
  }
  baton->tileFormat = AttrAsStr(options, "tileFormat");
+  std::string tileDepth = AttrAsStr(options, "tileDepth");
+  if (tileDepth == "onetile") {
+    baton->tileDepth = VIPS_FOREIGN_DZ_DEPTH_ONETILE;
+  } else if (tileDepth == "one") {
+    baton->tileDepth = VIPS_FOREIGN_DZ_DEPTH_ONE;
+  } else if (tileDepth == "onepixel") {
+    baton->tileDepth = VIPS_FOREIGN_DZ_DEPTH_ONEPIXEL;
+  } else {
+    // signal that we do not want to pass any value to dzSave
+    baton->tileDepth = VIPS_FOREIGN_DZ_DEPTH_LAST;
+  }
  // Force random access for certain operations
  if (baton->accessMethod == VIPS_ACCESS_SEQUENTIAL && (
    baton->trimTolerance != 0 || baton->normalise ||
--- a/src/pipeline.h
+++ b/src/pipeline.h
@@ -102,8 +102,10 @@ struct PipelineBaton {
  bool jpegProgressive;
  std::string jpegChromaSubsampling;
  bool jpegTrellisQuantisation;
+  int jpegQuantisationTable;
  bool jpegOvershootDeringing;
  bool jpegOptimiseScans;
+  bool jpegOptimiseCoding;
  bool pngProgressive;
  int pngCompressionLevel;
  bool pngAdaptiveFiltering;
@@ -129,6 +131,7 @@ struct PipelineBaton {
  VipsOperationBoolean booleanOp;
  VipsOperationBoolean bandBoolOp;
  int extractChannel;
+  bool removeAlpha;
  VipsInterpretation colourspace;
  int tileSize;
  int tileOverlap;
@@ -136,6 +139,7 @@ struct PipelineBaton {
  VipsForeignDzLayout tileLayout;
  std::string tileFormat;
  int tileAngle;
+  VipsForeignDzDepth tileDepth;

  PipelineBaton():
    input(nullptr),
@@ -187,8 +191,10 @@ struct PipelineBaton {
    jpegProgressive(false),
    jpegChromaSubsampling("4:2:0"),
    jpegTrellisQuantisation(false),
+    jpegQuantisationTable(0),
    jpegOvershootDeringing(false),
    jpegOptimiseScans(false),
+    jpegOptimiseCoding(true),
    pngProgressive(false),
    pngCompressionLevel(9),
    pngAdaptiveFiltering(false),
@@ -209,12 +215,14 @@ struct PipelineBaton {
    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){
+    tileAngle(0),
+    tileDepth(VIPS_FOREIGN_DZ_DEPTH_LAST){
      background[0] = 0.0;
      background[1] = 0.0;
      background[2] = 0.0;
--- a/src/stats.cc
+++ b/src/stats.cc
@@ -59,7 +59,6 @@ class StatsWorker : public Nan::AsyncWorker {
    using sharp::MaximumImageAlpha;

    vips::VImage image;
-    vips::VImage stats;
    sharp::ImageType imageType = sharp::ImageType::UNKNOWN;

    try {
@@ -69,9 +68,8 @@ class StatsWorker : public Nan::AsyncWorker {
    }
    if (imageType != sharp::ImageType::UNKNOWN) {
      try {
-        stats = image.stats();
-        int bands = image.bands();
-        double const max = MaximumImageAlpha(image.interpretation());
+        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()),
@@ -83,11 +81,15 @@ class StatsWorker : public Nan::AsyncWorker {
                              static_cast<int>(stats.getpoint(STAT_MAXY_INDEX, b).front()));
          baton->channelStats.push_back(cStats);
        }
-
-        // alpha layer is there and the last band i.e. alpha has its max value greater than 0)
-        if (sharp::HasAlpha(image) && stats.getpoint(STAT_MIN_INDEX, bands).front() != max) {
-          baton->isOpaque = false;
+        // 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());
      }
@@ -130,6 +132,7 @@ class StatsWorker : public Nan::AsyncWorker {

      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;
    }

--- a/src/stats.h
+++ b/src/stats.h
@@ -51,12 +51,14 @@ struct StatsBaton {
  // Output
  std::vector<ChannelStats> channelStats;
  bool isOpaque;
+  double entropy;

  std::string err;

  StatsBaton():
    input(nullptr),
-    isOpaque(true)
+    isOpaque(true),
+    entropy(0.0)
    {}
 };

--- a/test/fixtures/expected/extract-alpha-16bit.jpg
+++ b/test/fixtures/expected/extract-alpha-16bit.jpg
--- a/test/unit/alpha.js
+++ b/test/unit/alpha.js
@@ -81,35 +81,45 @@ describe('Alpha transparency', function () {
      });
  });

-  it('Enlargement with non-nearest neighbor interpolation shouldn’t cause dark edges', function (done) {
+  it('Enlargement with non-nearest neighbor interpolation shouldn’t cause dark edges', function () {
    const base = 'alpha-premultiply-enlargement-2048x1536-paper.png';
    const actual = fixtures.path('output.' + base);
    const expected = fixtures.expected(base);
-    sharp(fixtures.inputPngAlphaPremultiplicationSmall)
+    return sharp(fixtures.inputPngAlphaPremultiplicationSmall)
      .resize(2048, 1536)
-      .toFile(actual, function (err) {
-        if (err) {
-          done(err);
-        } else {
-          fixtures.assertMaxColourDistance(actual, expected, 102);
-          done();
-        }
+      .toFile(actual)
+      .then(function () {
+        fixtures.assertMaxColourDistance(actual, expected, 102);
      });
  });

-  it('Reduction with non-nearest neighbor interpolation shouldn’t cause dark edges', function (done) {
+  it('Reduction with non-nearest neighbor interpolation shouldn’t cause dark edges', function () {
    const base = 'alpha-premultiply-reduction-1024x768-paper.png';
    const actual = fixtures.path('output.' + base);
    const expected = fixtures.expected(base);
-    sharp(fixtures.inputPngAlphaPremultiplicationLarge)
+    return sharp(fixtures.inputPngAlphaPremultiplicationLarge)
      .resize(1024, 768)
-      .toFile(actual, function (err) {
-        if (err) {
-          done(err);
-        } else {
-          fixtures.assertMaxColourDistance(actual, expected, 102);
-          done();
-        }
+      .toFile(actual)
+      .then(function () {
+        fixtures.assertMaxColourDistance(actual, expected, 102);
      });
  });
+
+  it('Removes alpha from fixtures with transparency, ignores those without', function () {
+    return Promise.all([
+      fixtures.inputPngWithTransparency,
+      fixtures.inputPngWithTransparency16bit,
+      fixtures.inputWebPWithTransparency,
+      fixtures.inputJpg,
+      fixtures.inputPng,
+      fixtures.inputWebP
+    ].map(function (input) {
+      return sharp(input)
+        .removeAlpha()
+        .toBuffer({ resolveWithObject: true })
+        .then(function (result) {
+          assert.strictEqual(3, result.info.channels);
+        });
+    }));
+  });
 });
--- a/test/unit/extractChannel.js
+++ b/test/unit/extractChannel.js
@@ -69,6 +69,17 @@ describe('Image channel extraction', function () {
      });
  });

+  it('Alpha from 16-bit PNG', function (done) {
+    const output = fixtures.path('output.extract-alpha-16bit.jpg');
+    sharp(fixtures.inputPngWithTransparency16bit)
+      .extractChannel(3)
+      .toFile(output, function (err, info) {
+        if (err) throw err;
+        fixtures.assertMaxColourDistance(output, fixtures.expected('extract-alpha-16bit.jpg'));
+        done();
+      });
+  });
+
  it('Invalid channel number', function () {
    assert.throws(function () {
      sharp(fixtures.inputJpg)
--- a/test/unit/io.js
+++ b/test/unit/io.js
@@ -389,6 +389,16 @@ describe('Input/output', function () {
    });
  });

+  describe('Invalid JPEG quantisation table', function () {
+    [-1, 88.2, 'test'].forEach(function (table) {
+      it(table.toString(), function () {
+        assert.throws(function () {
+          sharp().jpeg({ quantisationTable: table });
+        });
+      });
+    });
+  });
+
  it('Progressive JPEG image', function (done) {
    sharp(fixtures.inputJpg)
      .resize(320, 240)
@@ -826,6 +836,67 @@ describe('Input/output', function () {
      });
  });

+  it('Optimise coding generates smaller output length', function (done) {
+    // First generate with optimize coding enabled (default)
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .jpeg()
+      .toBuffer(function (err, withOptimiseCoding, withInfo) {
+        if (err) throw err;
+        assert.strictEqual(true, withOptimiseCoding.length > 0);
+        assert.strictEqual(withOptimiseCoding.length, withInfo.size);
+        assert.strictEqual('jpeg', withInfo.format);
+        assert.strictEqual(320, withInfo.width);
+        assert.strictEqual(240, withInfo.height);
+        // Then generate with coding disabled
+        sharp(fixtures.inputJpg)
+          .resize(320, 240)
+          .jpeg({ optimizeCoding: false })
+          .toBuffer(function (err, withoutOptimiseCoding, withoutInfo) {
+            if (err) throw err;
+            assert.strictEqual(true, withoutOptimiseCoding.length > 0);
+            assert.strictEqual(withoutOptimiseCoding.length, withoutInfo.size);
+            assert.strictEqual('jpeg', withoutInfo.format);
+            assert.strictEqual(320, withoutInfo.width);
+            assert.strictEqual(240, withoutInfo.height);
+            // Verify optimised image is of a smaller size
+            assert.strictEqual(true, withOptimiseCoding.length < withoutOptimiseCoding.length);
+            done();
+          });
+      });
+  });
+
+  it('Specifying quantisation table provides different JPEG', function (done) {
+    // First generate with default quantisation table
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .jpeg({ optimiseCoding: false })
+      .toBuffer(function (err, withDefaultQuantisationTable, withInfo) {
+        if (err) throw err;
+        assert.strictEqual(true, withDefaultQuantisationTable.length > 0);
+        assert.strictEqual(withDefaultQuantisationTable.length, withInfo.size);
+        assert.strictEqual('jpeg', withInfo.format);
+        assert.strictEqual(320, withInfo.width);
+        assert.strictEqual(240, withInfo.height);
+        // Then generate with different quantisation table
+        sharp(fixtures.inputJpg)
+          .resize(320, 240)
+          .jpeg({ optimiseCoding: false, quantisationTable: 3 })
+          .toBuffer(function (err, withQuantTable3, withoutInfo) {
+            if (err) throw err;
+            assert.strictEqual(true, withQuantTable3.length > 0);
+            assert.strictEqual(withQuantTable3.length, withoutInfo.size);
+            assert.strictEqual('jpeg', withoutInfo.format);
+            assert.strictEqual(320, withoutInfo.width);
+            assert.strictEqual(240, withoutInfo.height);
+
+            // Verify image is same (as mozjpeg may not be present) size or less
+            assert.strictEqual(true, withQuantTable3.length <= withDefaultQuantisationTable.length);
+            done();
+          });
+      });
+  });
+
  it('Convert SVG to PNG at default 72DPI', function (done) {
    sharp(fixtures.inputSvg)
      .resize(1024)
--- a/test/unit/libvips.js
+++ b/test/unit/libvips.js
@@ -1,6 +1,7 @@
 'use strict';

 const assert = require('assert');
+const fs = require('fs');
 const semver = require('semver');
 const libvips = require('../../lib/libvips');

@@ -66,5 +67,11 @@ describe('libvips binaries', function () {

      delete process.env.SHARP_IGNORE_GLOBAL_LIBVIPS;
    });
+    it('cachePath returns a valid path ending with _libvips', function () {
+      const cachePath = libvips.cachePath();
+      assert.strictEqual('string', typeof cachePath);
+      assert.strictEqual('_libvips', cachePath.substr(-8));
+      assert.strictEqual(true, fs.existsSync(cachePath));
+    });
  });
 });
--- a/test/unit/stats.js
+++ b/test/unit/stats.js
@@ -24,6 +24,7 @@ describe('Image Stats', function () {
      if (err) throw err;

      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 7.319914765248541));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -82,6 +83,7 @@ describe('Image Stats', function () {
      if (err) throw err;

      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 0.3409031108021736));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -105,7 +107,9 @@ describe('Image Stats', function () {
  it('PNG with transparency', function (done) {
    sharp(fixtures.inputPngWithTransparency).stats(function (err, stats) {
      if (err) throw err;
+
      assert.strictEqual(false, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 0.06778064835816622));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -180,6 +184,7 @@ describe('Image Stats', function () {
      if (err) throw err;

      assert.strictEqual(false, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 0));

      // alpha channel
      assert.strictEqual(0, stats.channels[3]['min']);
@@ -204,7 +209,9 @@ describe('Image Stats', function () {
  it('Tiff', function (done) {
    sharp(fixtures.inputTiff).stats(function (err, stats) {
      if (err) throw err;
+
      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 0.3851250782608986));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -231,6 +238,7 @@ describe('Image Stats', function () {
      if (err) throw err;

      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 7.51758075132966));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -289,6 +297,7 @@ describe('Image Stats', function () {
      if (err) throw err;

      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 6.087309412541799));

      // red channel
      assert.strictEqual(35, stats.channels[0]['min']);
@@ -345,7 +354,9 @@ describe('Image Stats', function () {
  it('Grayscale GIF with alpha', function (done) {
    sharp(fixtures.inputGifGreyPlusAlpha).stats(function (err, stats) {
      if (err) throw err;
+
      assert.strictEqual(false, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 1));

      // gray channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -387,7 +398,9 @@ describe('Image Stats', function () {
    const readable = fs.createReadStream(fixtures.inputJpg);
    const pipeline = sharp().stats(function (err, stats) {
      if (err) throw err;
+
      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 7.319914765248541));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -449,6 +462,7 @@ describe('Image Stats', function () {

    return pipeline.stats().then(function (stats) {
      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 7.319914765248541));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
@@ -505,6 +519,7 @@ describe('Image Stats', function () {
  it('File in, Promise out', function () {
    return sharp(fixtures.inputJpg).stats().then(function (stats) {
      assert.strictEqual(true, stats.isOpaque);
+      assert.strictEqual(true, isInAcceptableRange(stats.entropy, 7.319914765248541));

      // red channel
      assert.strictEqual(0, stats.channels[0]['min']);
--- a/test/unit/tile.js
+++ b/test/unit/tile.js
@@ -46,6 +46,51 @@ const assertDeepZoomTiles = function (directory, expectedSize, expectedLevels, d
  }, done);
 };

+const assertZoomifyTiles = function (directory, expectedTileSize, expectedLevels, done) {
+  fs.stat(path.join(directory, 'ImageProperties.xml'), function (err, stat) {
+    if (err) throw err;
+    assert.ok(stat.isFile());
+    assert.ok(stat.size > 0);
+
+    let maxTileLevel = -1;
+    fs.readdirSync(path.join(directory, 'TileGroup0')).forEach(function (tile) {
+      // Verify tile file name
+      assert.ok(/^[0-9]+-[0-9]+-[0-9]+\.jpg$/.test(tile));
+      let level = parseInt(tile.split('-')[0]);
+      maxTileLevel = Math.max(maxTileLevel, level);
+    });
+
+    assert.strictEqual(maxTileLevel + 1, expectedLevels); // add one to account for zero level tile
+
+    done();
+  });
+};
+
+const assertGoogleTiles = function (directory, expectedTileSize, expectedLevels, done) {
+  const levels = fs.readdirSync(directory);
+  assert.strictEqual(expectedLevels, levels.length - 1); // subtract one to account for default blank tile
+
+  fs.stat(path.join(directory, 'blank.png'), function (err, stat) {
+    if (err) throw err;
+    assert.ok(stat.isFile());
+    assert.ok(stat.size > 0);
+
+    // Basic check to confirm lowest and highest level tiles exist
+    fs.stat(path.join(directory, '0', '0', '0.jpg'), function (err, stat) {
+      if (err) throw err;
+      assert.strictEqual(true, stat.isFile());
+      assert.strictEqual(true, stat.size > 0);
+
+      fs.stat(path.join(directory, (expectedLevels - 1).toString(), '0', '0.jpg'), function (err, stat) {
+        if (err) throw err;
+        assert.strictEqual(true, stat.isFile());
+        assert.strictEqual(true, stat.size > 0);
+        done();
+      });
+    });
+  });
+};
+
 describe('Tile', function () {
  it('Valid size values pass', function () {
    [1, 8192].forEach(function (size) {
@@ -144,6 +189,26 @@ describe('Tile', function () {
    });
  });

+  it('Valid depths pass', function () {
+    ['onepixel', 'onetile', 'one'].forEach(function (depth) {
+      assert.doesNotThrow(function (depth) {
+        sharp().tile({
+          depth: depth
+        });
+      });
+    });
+  });
+
+  it('Invalid depths fail', function () {
+    ['depth', 1].forEach(function (depth) {
+      assert.throws(function () {
+        sharp().tile({
+          depth: depth
+        });
+      });
+    });
+  });
+
  it('Prevent larger overlap than default size', function () {
    assert.throws(function () {
      sharp().tile({
@@ -251,6 +316,54 @@ describe('Tile', function () {
    });
  });

+  it('Deep Zoom layout with depth of one', function (done) {
+    const directory = fixtures.path('output.512_depth_one.dzi_files');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 512,
+          depth: 'one'
+        })
+        .toFile(fixtures.path('output.512_depth_one.dzi'), function (err, info) {
+          if (err) throw err;
+          // Verify only one depth generated
+          assertDeepZoomTiles(directory, 512, 1, done);
+        });
+    });
+  });
+
+  it('Deep Zoom layout with depth of onepixel', function (done) {
+    const directory = fixtures.path('output.512_depth_onepixel.dzi_files');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 512,
+          depth: 'onepixel'
+        })
+        .toFile(fixtures.path('output.512_depth_onepixel.dzi'), function (err, info) {
+          if (err) throw err;
+          // Verify only one depth generated
+          assertDeepZoomTiles(directory, 512, 13, done);
+        });
+    });
+  });
+
+  it('Deep Zoom layout with depth of onetile', function (done) {
+    const directory = fixtures.path('output.256_depth_onetile.dzi_files');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 256,
+          depth: 'onetile'
+        })
+        .toFile(fixtures.path('output.256_depth_onetile.dzi'), function (err, info) {
+          if (err) throw err;
+          // Verify only one depth generated
+          assertDeepZoomTiles(directory, 256, 5, done);
+        });
+    });
+  });
+
  it('Zoomify layout', function (done) {
    const directory = fixtures.path('output.zoomify.dzi');
    rimraf(directory, function () {
@@ -275,6 +388,69 @@ describe('Tile', function () {
    });
  });

+  it('Zoomify layout with depth one', function (done) {
+    const directory = fixtures.path('output.zoomify.depth_one.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 256,
+          layout: 'zoomify',
+          depth: 'one'
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+          assertZoomifyTiles(directory, 256, 1, done);
+        });
+    });
+  });
+
+  it('Zoomify layout with depth onetile', function (done) {
+    const directory = fixtures.path('output.zoomify.depth_onetile.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 256,
+          layout: 'zoomify',
+          depth: 'onetile'
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+          assertZoomifyTiles(directory, 256, 5, done);
+        });
+    });
+  });
+
+  it('Zoomify layout with depth onepixel', function (done) {
+    const directory = fixtures.path('output.zoomify.depth_onepixel.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          size: 256,
+          layout: 'zoomify',
+          depth: 'onepixel'
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+          assertZoomifyTiles(directory, 256, 13, done);
+        });
+    });
+  });
+
  it('Google layout', function (done) {
    const directory = fixtures.path('output.google.dzi');
    rimraf(directory, function () {
@@ -410,6 +586,72 @@ describe('Tile', function () {
    });
  });

+  it('Google layout with depth one', function (done) {
+    const directory = fixtures.path('output.google_depth_one.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          layout: 'google',
+          depth: 'one',
+          size: 256
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+
+          assertGoogleTiles(directory, 256, 1, done);
+        });
+    });
+  });
+
+  it('Google layout with depth onepixel', function (done) {
+    const directory = fixtures.path('output.google_depth_onepixel.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          layout: 'google',
+          depth: 'onepixel',
+          size: 256
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+
+          assertGoogleTiles(directory, 256, 13, done);
+        });
+    });
+  });
+
+  it('Google layout with depth onetile', function (done) {
+    const directory = fixtures.path('output.google_depth_onetile.dzi');
+    rimraf(directory, function () {
+      sharp(fixtures.inputJpg)
+        .tile({
+          layout: 'google',
+          depth: 'onetile',
+          size: 256
+        })
+        .toFile(directory, function (err, info) {
+          if (err) throw err;
+          assert.strictEqual('dz', info.format);
+          assert.strictEqual(2725, info.width);
+          assert.strictEqual(2225, info.height);
+          assert.strictEqual(3, info.channels);
+          assert.strictEqual('number', typeof info.size);
+
+          assertGoogleTiles(directory, 256, 5, done);
+        });
+    });
+  });
+
  it('Write to ZIP container using file extension', function (done) {
    const container = fixtures.path('output.dz.container.zip');
    const extractTo = fixtures.path('output.dz.container');
Author	SHA1	Message	Date
Lovell Fuller	a15a9b956b	Release v0.20.6	2018-08-20 11:40:10 +01:00
Lovell Fuller	42860c2f83	Changelog, credit and doc refresh for #1342	2018-08-19 10:43:25 +01:00
Alun Davies	b5b95e5ae1	Expose depth option for tile-based output (#1342 )	2018-08-18 15:09:53 +01:00
Lovell Fuller	d705cffdd6	Ensure extractChannel works with 16-bit images #1330	2018-08-12 20:22:39 +01:00
Rodrigo Alviani	23a4bc103e	Docs: correct quality option in overlayWith example (#1325 )	2018-08-08 08:42:18 +01:00
Lovell Fuller	c14434f9e7	Add removeAlpha op, removes alpha channel if any #1248	2018-08-07 20:32:11 +01:00
Lovell Fuller	25bd2cea3e	Add experimental entropy field to stats response	2018-08-06 15:41:27 +01:00
Lovell Fuller	532de4ecab	Cache libvips binaries to reduce re-install time #1301	2018-08-05 10:31:41 +01:00
Lovell Fuller	bfdd27eeef	Doc refresh and dependency bumps	2018-08-05 09:42:09 +01:00
Lovell Fuller	bd9f238ab4	Improve install time error messages for FreeBSD #1310	2018-08-04 22:27:32 +01:00
Lovell Fuller	75556bb57c	Ensure vendor platform mismatch throws error #1303	2018-08-04 21:34:11 +01:00
thegareth	2de062a34a	Docs: update the "make a transparent image" example (#1316 ) Alpha for colour is between 0-1, not 0-255.	2018-08-02 09:42:25 +01:00
Lovell Fuller	4589b15dea	Changelog and credit for #1285 #1290	2018-07-10 16:12:16 +01:00
Sylvain Dumont	8b75ce6786	Allow full WebP alphaQuality range of 0-100 (#1290 )	2018-07-10 15:58:17 +01:00
Espen Hovlandsdal	7bbc5176a1	Expose mozjpeg quant_table flag (#1285 )	2018-07-10 15:56:05 +01:00
Lovell Fuller	5cb35485f1	Release v0.20.5	2018-06-27 08:44:31 +01:00
Lovell Fuller	80189ed689	Add changelog and credit for #1265	2018-06-27 07:54:41 +01:00
Muhammad Faheem Akhtar	3d7e8ef432	Docs: update new Buffer() to Buffer.from() (#1273 )	2018-06-26 08:19:27 +01:00
Lovell Fuller	1999c7103c	Docs: add CSS to improve left-hand nav nesting	2018-06-25 19:58:50 +01:00
Thomas Vantuycom	9c20ae383e	Remove top of file table of contents in documentation (#1270 )	2018-06-24 21:45:51 +01:00
Tom Lokhorst	76c41eaf05	Expose libjpeg optimize_coding flag (#1265 )	2018-06-21 18:12:10 +01:00