mirror of https://github.com/lovell/sharp.git synced 2025-07-09 10:30:15 +02:00

Lovell Fuller 18b9991fe7 Add experimental 'attention' crop strategy

2016-10-12 11:18:58 +01:00

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API

var sharp = require('sharp');

Input

sharp([input], [options])

Constructor to which further methods are chained.

input, if present, can be one of:

Buffer containing JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data, or
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 input is null or undefined.

options, if present, is an Object with the following optional attributes:

density an integral number representing the DPI for vector images, defaulting to 72.
raw an Object containing width, height and channels when providing uncompressed data. See raw() for pixel ordering.

The object returned by the constructor implements the stream.Duplex class.

JPEG, PNG or WebP format image data can be streamed out from this object. When using Stream based output, derived attributes are available from the info event.

sharp('input.jpg')
  .resize(300, 200)
  .toFile('output.jpg', function(err) {
    // output.jpg is a 300 pixels wide and 200 pixels high image
    // containing a scaled and cropped version of input.jpg
  });

// Read image data from readableStream,
// resize to 300 pixels wide,
// emit an 'info' event with calculated dimensions
// and finally write image data to writableStream
var transformer = sharp()
  .resize(300)
  .on('info', function(info) {
    console.log('Image height is ' + info.height);
  });
readableStream.pipe(transformer).pipe(writableStream);

metadata([callback])

Fast access to image metadata without decoding any compressed image data.

callback, if present, gets the arguments (err, metadata) where metadata has the attributes:

format: Name of decoder used to decompress image data e.g. jpeg, png, webp, gif, svg
width: Number of pixels wide
height: Number of pixels high
space: Name of colour space interpretation e.g. srgb, rgb, scrgb, cmyk, lab, xyz, b-w ...
channels: Number of bands e.g. 3 for sRGB, 4 for CMYK
density: Number of pixels per inch (DPI), if present
hasProfile: Boolean indicating the presence of an embedded ICC profile
hasAlpha: Boolean indicating the presence of an alpha transparency channel
orientation: Number value of the EXIF Orientation header, if present
exif: Buffer containing raw EXIF data, if present
icc: Buffer containing raw ICC profile data, if present

A Promises/A+ promise is returned when callback is not provided.

var image = sharp(inputJpg);
image
  .metadata()
  .then(function(metadata) {
    return image
      .resize(Math.round(metadata.width / 2))
      .webp()
      .toBuffer();
  })
  .then(function(data) {
    // data contains a WebP image half the width and height of the original JPEG
  });

clone()

Takes a "snapshot" of the instance, returning a new instance. Cloned instances inherit the input of their parent instance.

This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.

var pipeline = sharp().rotate();
pipeline.clone().resize(800, 600).pipe(firstWritableStream);
pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
readableStream.pipe(pipeline);
// firstWritableStream receives auto-rotated, resized readableStream
// secondWritableStream receives auto-rotated, extracted region of readableStream

sequentialRead()

An advanced setting that switches the libvips access method to VIPS_ACCESS_SEQUENTIAL. This will reduce memory usage and can improve performance on some systems.

limitInputPixels(pixels)

Do not process input images where the number of pixels (width * height) exceeds this limit.

pixels is either an integral Number of pixels, with a value between 1 and the default 268402689 (0x3FFF * 0x3FFF) or a boolean. false will disable checking while true will revert to the default limit.

Resizing

resize([width], [height], [options])

Scale output to width x height. By default, the resized image is cropped to the exact size specified.

width is the integral Number of pixels wide the resultant image should be, between 1 and 16383 (0x3FFF). Use null or undefined to auto-scale the width to match the height.

height is the integral Number of pixels high the resultant image should be, between 1 and 16383. Use null or undefined to auto-scale the height to match the width.

options is an optional Object. If present, it can contain one or more of:

options.kernel, the kernel to use for image reduction, defaulting to lanczos3.
options.interpolator, the interpolator to use for image enlargement, defaulting to bicubic.

Possible kernels are:

cubic: Use a Catmull-Rom spline.
lanczos2: Use a Lanczos kernel with a=2.
lanczos3: Use a Lanczos kernel with a=3 (the default).

Possible interpolators are:

nearest: Use nearest neighbour interpolation.
bilinear: Use bilinear interpolation, faster than bicubic but with less smooth results.
vertexSplitQuadraticBasisSpline: Use the smoother VSQBS interpolation to prevent "staircasing" when enlarging.
bicubic: Use bicubic interpolation (the default).
locallyBoundedBicubic: Use LBB interpolation, which prevents some "acutance" but typically reduces performance by a factor of 2.
nohalo: Use Nohalo interpolation, which prevents acutance but typically reduces performance by a factor of 3.

sharp(inputBuffer)
  .resize(200, 300, {
    kernel: sharp.kernel.lanczos2,
    interpolator: sharp.interpolator.nohalo
  })
  .background('white')
  .embed()
  .toFile('output.tiff')
  .then(function() {
    // output.tiff is a 200 pixels wide and 300 pixels high image
    // containing a lanczos2/nohalo scaled version, embedded on a white canvas,
    // of the image data in inputBuffer
  });

crop([option])

Crop the resized image to the exact size specified, the default behaviour.

option, if present, is an attribute of:

sharp.gravity e.g. sharp.gravity.north, to crop to an edge or corner, or
sharp.strategy e.g. sharp.strategy.entropy, to crop dynamically.

Possible attributes of sharp.gravity are north, northeast, east, southeast, south, southwest, west, northwest, center and centre.

The experimental strategy-based approach resizes so one dimension is at its target length then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.

entropy: focus on the region with the highest Shannon entropy.
attention: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.

The default crop option is a center/centre gravity.

var transformer = sharp()
  .resize(200, 200)
  .crop(sharp.strategy.entropy)
  .on('error', function(err) {
    console.log(err);
  });
// Read image data from readableStream
// Write 200px square auto-cropped image data to writableStream
readableStream.pipe(transformer).pipe(writableStream);

embed()

Preserving aspect ratio, resize the image to the maximum width or height specified then embed on a background of the exact width and height specified.

If the background contains an alpha value then WebP and PNG format output images will contain an alpha channel, even when the input image does not.

sharp('input.gif')
  .resize(200, 300)
  .background({r: 0, g: 0, b: 0, a: 0})
  .embed()
  .toFormat(sharp.format.webp)
  .toBuffer(function(err, outputBuffer) {
    if (err) {
      throw err;
    }
    // outputBuffer contains WebP image data of a 200 pixels wide and 300 pixels high
    // containing a scaled version, embedded on a transparent canvas, of input.gif
  });

max()

Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to the width and height specified.

Both width and height must be provided via resize otherwise the behaviour will default to crop.

sharp(inputBuffer)
  .resize(200, 200)
  .max()
  .toFormat('jpeg')
  .toBuffer()
  .then(function(outputBuffer) {
    // outputBuffer contains JPEG image data no wider than 200 pixels and no higher
    // than 200 pixels regardless of the inputBuffer image dimensions
  });

min()

Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to the width and height specified.

Both width and height must be provided via resize otherwise the behaviour will default to crop.

withoutEnlargement()

Do not enlarge the output image if the input image width or height are already less than the required dimensions.

This is equivalent to GraphicsMagick's > geometry option: "change the dimensions of the image only if its width or height exceeds the geometry specification".

ignoreAspectRatio()

Ignoring the aspect ratio of the input, stretch the image to the exact width and/or height provided via resize.

Operations

extract({ left: left, top: top, width: width, height: height })

Extract a region of the image. Can be used with or without a resize operation.

left and top are the offset, in pixels, from the top-left corner.

width and height are the dimensions of the extracted image.

Use extract before resize for pre-resize extraction. Use extract after resize for post-resize extraction. Use extract before and after for both.

sharp(input)
  .extract({ left: left, top: top, width: width, height: height })
  .toFile(output, function(err) {
    // Extract a region of the input image, saving in the same format.
  });

sharp(input)
  .extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
  .resize(width, height)
  .extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
  .toFile(output, function(err) {
    // Extract a region, resize, then extract from the resized image
  });

trim([tolerance])

Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel.

tolerance, if present, is an integral Number between 1 and 99 representing the percentage similarity, defaulting to 10.

background(rgba)

Set the background for the embed, flatten and extend operations.

rgba is parsed by the color module to extract values for red, green, blue and alpha.

The alpha value is a float between 0 (transparent) and 1 (opaque).

The default background is {r: 0, g: 0, b: 0, a: 1}, black without transparency.

flatten()

Merge alpha transparency channel, if any, with background.

extend(extension)

Extends/pads the edges of the image with background, where extension is one of:

a Number representing the pixel count to add to each edge, or
an Object containing top, left, bottom and right attributes, each a Number of pixels to add to that edge.

This operation will always occur after resizing and extraction, if any.

// Resize to 140 pixels wide, then add 10 transparent pixels
// to the top, left and right edges and 20 to the bottom edge
sharp(input)
  .resize(140)
  .background({r: 0, g: 0, b: 0, a: 0})
  .extend({top: 10, bottom: 20, left: 10, right: 10})
  ...

negate()

Produces the "negative" of the image. White => Black, Black => White, Blue => Yellow, etc.

rotate([angle])

Rotate the output image by either an explicit angle or auto-orient based on the EXIF Orientation tag.

angle, if present, is a Number with a value of 0, 90, 180 or 270.

Use this method without angle to determine the angle from EXIF data. Mirroring is supported and may infer the use of a flip operation.

Method order is important when both rotating and extracting regions, for example rotate(x).extract(y) will produce a different result to extract(y).rotate(x).

The use of rotate implies the removal of the EXIF Orientation tag, if any.

var pipeline = sharp()
  .rotate()
  .resize(null, 200)
  .progressive()
  .toBuffer(function(err, outputBuffer, info) {
    if (err) {
      throw err;
    }
    // outputBuffer contains 200px high progressive JPEG image data,
    // auto-rotated using EXIF Orientation tag
    // info.width and info.height contain the dimensions of the resized image
  });
readableStream.pipe(pipeline);

flip()

Flip the image about the vertical Y axis. This always occurs after rotation, if any. The use of flip implies the removal of the EXIF Orientation tag, if any.

flop()

Flop the image about the horizontal X axis. This always occurs after rotation, if any. The use of flop implies the removal of the EXIF Orientation tag, if any.

blur([sigma])

When used without parameters, performs a fast, mild blur of the output image. This typically reduces performance by 10%.

When a sigma is provided, performs a slower, more accurate Gaussian blur. This typically reduces performance by 25%.

sigma, if present, is a Number between 0.3 and 1000 representing the sigma of the Gaussian mask, where sigma = 1 + radius / 2.

convolve(kernel)

Convolve the image with the specified kernel, an Object with the following attributes:

width is an integral Number representing the width of the kernel in pixels.
height is an integral Number representing the width of the kernel in pixels.
kernel is an Array of length width*height containing the kernel values.
scale, if present, is a Number representing the scale of the kernel in pixels, defaulting to the sum of the kernel's values.
offset, if present, is a Number representing the offset of the kernel in pixels, defaulting to 0.

sharp(input)
  .convolve({
    width: 3,
    height: 3,
    kernel: [-1, 0, 1, -2, 0, 2, -1, 0, 1]
  })
  .raw()
  .toBuffer(function(err, data, info) {
    // data contains the raw pixel data representing the convolution
    // of the input image with the horizontal Sobel operator
  });

sharpen([sigma], [flat], [jagged])

When used without parameters, performs a fast, mild sharpen of the output image. This typically reduces performance by 10%.

When a sigma is provided, performs a slower, more accurate sharpen of the L channel in the LAB colour space. Separate control over the level of sharpening in "flat" and "jagged" areas is available. This typically reduces performance by 50%.

sigma, if present, is a Number representing the sigma of the Gaussian mask, where sigma = 1 + radius / 2.
flat, if present, is a Number representing the level of sharpening to apply to "flat" areas, defaulting to a value of 1.0.
jagged, if present, is a Number representing the level of sharpening to apply to "jagged" areas, defaulting to a value of 2.0.

threshold([threshold], [options])

Any pixel value greather than or equal to the threshold value will be set to 255, otherwise it will be set to 0. By default, the image will be converted to single channel greyscale before thresholding.

threshold, if present, is a Number between 0 and 255, representing the level at which the threshold will be applied. The default threshold is 128.
options, if present, is an Object containing a Boolean greyscale (or grayscale). When false each channel will have the threshold applied independently.

gamma([gamma])

Apply a gamma correction by reducing the encoding (darken) pre-resize at a factor of 1/gamma then increasing the encoding (brighten) post-resize at a factor of gamma.

gamma, if present, is a Number between 1 and 3. The default value is 2.2, a suitable approximation for sRGB images.

This can improve the perceived brightness of a resized image in non-linear colour spaces.

JPEG input images will not take advantage of the shrink-on-load performance optimisation when applying a gamma correction.

grayscale() / greyscale()

Convert to 8-bit greyscale; 256 shades of grey.

This is a linear operation. If the input image is in a non-linear colour space such as sRGB, use gamma() with greyscale() for the best results.

By default the output image will be web-friendly sRGB and contain three (identical) color channels. This may be overridden by other sharp operations such as toColourspace('b-w'), which will produce an output image containing one color channel. An alpha channel may be present, and will be unchanged by the operation.

normalize() / normalise()

Enhance output image contrast by stretching its luminance to cover the full dynamic range. This typically reduces performance by 30%.

overlayWith(image, [options])

Overlay (composite) a image over the processed (resized, extracted etc.) image.

image is one of the following, and must be the same size or smaller than the processed image:

Buffer containing image data, or
String containing the path to an image file

options, if present, is an Object with the following optional attributes:

gravity is a String or an attribute of the sharp.gravity Object e.g. sharp.gravity.north at which to place the overlay, defaulting to center/centre.
top is an integral Number representing the pixel offset from the top edge.
left is an integral Number representing the pixel offset from the left edge.
tile is a Boolean, defaulting to false. When set to true repeats the overlay image across the entire image with the given gravity.
cutout is a Boolean, defaulting to false. When set to true applies only the alpha channel of the overlay image to the image to be overlaid, giving the appearance of one image being cut out of another.
raw an Object containing width, height and channels when providing uncompressed data.

If both top and left are provided, they take precedence over gravity.

sharp('input.png')
  .rotate(180)
  .resize(300)
  .flatten()
  .background('#ff6600')
  .overlayWith('overlay.png', { gravity: sharp.gravity.southeast } )
  .sharpen()
  .withMetadata()
  .quality(90)
  .webp()
  .toBuffer()
  .then(function(outputBuffer) {
    // outputBuffer contains upside down, 300px wide, alpha channel flattened
    // onto orange background, composited with overlay.png with SE gravity,
    // sharpened, with metadata, 90% quality WebP image data. Phew!
  });

toColourspace(colourspace) / toColorspace(colorspace)

Set the output colourspace. By default output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.

colourspace is a string or sharp.colourspace enum that identifies an output colourspace. String arguments comprise vips colour space interpretation names e.g. srgb, rgb, scrgb, cmyk, lab, xyz, b-w ...

extractChannel(channel)

Extract a single channel from a multi-channel image.

channel is a zero-indexed integral Number representing the band number to extract. red, green or blue are also accepted as an alternative to 0, 1 or 2 respectively.

sharp(input)
  .extractChannel('green')
  .toFile('input_green.jpg', function(err, info) {
    // info.channels === 1
    // input_green.jpg contains the green channel of the input image
   });

joinChannel(channels, [options])

Join a data channel to the image. The meaning of the added channels depends on the output colourspace, set with toColourspace(). By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.

channels is one of

a single file path
an array of file paths
a single buffer
an array of buffers

Note that channel ordering follows vips convention:

sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha
CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha

Buffers may be any of the image formats supported by sharp: JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data. In the case of a RAW buffer, the options object should contain a raw attribute, which follows the format of the attribute of the same name in the sharp() constructor. See sharp() for details. See raw() for pixel ordering.

bandbool(operation)

Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.

operation is a string containing the name of the bitwise operator to be appled to image channels, which can be one of:

and performs a bitwise and operation, like the c-operator &.
or performs a bitwise or operation, like the c-operator |.
eor performs a bitwise exclusive or operation, like the c-operator ^.

sharp('input.png')
  .bandbool(sharp.bool.and)
  .toFile('output.png')

In the above example if input.png is a 3 channel RGB image, output.png will be a 1 channel grayscale image where each pixel P = R & G & B. For example, if I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111] then O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2.

boolean(image, operation, [options])

Perform a bitwise boolean operation with image, where image is one of the following:

Buffer containing JPEG, PNG, WebP, GIF, SVG, TIFF or raw pixel image data, or
String containing the path to an image file

This operation creates an output image where each pixel is the result of the selected bitwise boolean operation between the corresponding pixels of the input images. The boolean operation can be one of the following:

and performs a bitwise and operation, like the c-operator &.
or performs a bitwise or operation, like the c-operator |.
eor performs a bitwise exclusive or operation, like the c-operator ^.

options, if present, is an Object with the following optional attributes:

raw an Object containing width, height and channels when providing uncompressed data.

Output

toFile(path, [callback])

path is a String containing the path to write the image data to.

If an explicit output format is not selected, it will be inferred from the extension, with JPEG, PNG, WebP, TIFF, DZI, and VIPS V format supported. Note that RAW format is only supported for buffer output.

callback, if present, is called with two arguments (err, info) where:

err contains an error message, if any.
info contains the output image format, size (bytes), width, height and channels.

A Promises/A+ promise is returned when callback is not provided.

toBuffer([callback])

Write image data to a Buffer, the format of which will match the input image by default. JPEG, PNG, WebP, and RAW are supported.

callback, if present, gets three arguments (err, buffer, info) where:

err is an error message, if any.
buffer is the output image data.
info contains the output image format, size (bytes), width, height and channels.

A Promises/A+ promise is returned when callback is not provided.

jpeg()

Use JPEG format for the output image.

png()

Use PNG format for the output image.

webp()

Use WebP format for the output image.

raw()

Provide raw, uncompressed uint8 (unsigned char) image data for Buffer and Stream based output.

The number of channels depends on the input image and selected options.

1 channel for images converted to greyscale(), with each byte representing one pixel.
3 channels for colour images without alpha transparency, with bytes ordered [red, green, blue, red, green, blue, etc.]).
4 channels for colour images with alpha transparency, with bytes ordered [red, green, blue, alpha, red, green, blue, alpha, etc.].

toFormat(format)

Convenience method for the above output format methods, where format is either:

an attribute of the sharp.format Object e.g. sharp.format.jpeg, or
a String containing jpeg, png, webp or raw.

quality(quality)

The output quality to use for lossy JPEG, WebP and TIFF output formats. The default quality is 80.

quality is a Number between 1 and 100.

progressive()

Use progressive (interlace) scan for JPEG and PNG output. This typically reduces compression performance by 30% but results in an image that can be rendered sooner when decompressed.

withMetadata([metadata])

Include all metadata (EXIF, XMP, IPTC) from the input image in the output image. This will also convert to and add the latest web-friendly v2 sRGB ICC profile.

The optional metadata parameter, if present, is an Object with the attributes to update. New attributes cannot be inserted, only existing attributes updated.

orientation is an integral Number between 1 and 8, used to update the value of the EXIF Orientation tag. This has no effect if the input image does not have an EXIF Orientation tag.

The default behaviour, when withMetadata is not used, is to strip all metadata and convert to the device-independent sRGB colour space.

tile(options)

The size, overlap, container and directory layout to use when generating square Deep Zoom image pyramid tiles.

options is an Object with one or more of the following attributes:

size is an integral Number between 1 and 8192. The default value is 256 pixels.
overlap is an integral Number between 0 and 8192. The default value is 0 pixels.
container is a String, with value fs or zip. The default value is fs.
layout is a String, with value dz, zoomify or google. The default value is dz.

You can also use the file extension .zip or .szi to write to a compressed archive file format.

sharp('input.tiff')
  .tile({
    size: 512
  })
  .toFile('output.dzi', function(err, info) {
    // output.dzi is the Deep Zoom XML definition
    // output_files contains 512x512 tiles grouped by zoom level
  });

withoutChromaSubsampling()

Disable the use of chroma subsampling with JPEG output (4:4:4).

This can improve colour representation at higher quality settings (90+), but usually increases output file size and typically reduces performance by 25%.

The default behaviour is to use chroma subsampling (4:2:0).

compressionLevel(compressionLevel)

An advanced setting for the zlib compression level of the lossless PNG output format. The default level is 6.

compressionLevel is a Number between 0 and 9.

withoutAdaptiveFiltering()

An advanced setting to disable adaptive row filtering for the lossless PNG output format.

trellisQuantisation() / trellisQuantization()

Requires libvips to have been compiled with mozjpeg support

An advanced setting to apply the use of trellis quantisation with JPEG output. Reduces file size and slightly increases relative quality at the cost of increased compression time.

overshootDeringing()

Requires libvips to have been compiled with mozjpeg support

An advanced setting to reduce the effects of ringing in JPEG output, in particular where black text appears on a white background (or vice versa).

optimiseScans() / optimizeScans()

Requires libvips to have been compiled with mozjpeg support

An advanced setting for progressive (interlace) JPEG output. Calculates which spectrum of DCT coefficients uses the fewest bits. Usually reduces file size at the cost of increased compression time.

Attributes

format

An Object containing nested boolean values representing the available input and output formats/methods, for example:

> console.dir(sharp.format);

{ jpeg: { id: 'jpeg',
    input: { file: true, buffer: true, stream: true },
    output: { file: true, buffer: true, stream: true } },
  png: { id: 'png',
    input: { file: true, buffer: true, stream: true },
    output: { file: true, buffer: true, stream: true } },
  webp: { id: 'webp',
    input: { file: true, buffer: true, stream: true },
    output: { file: true, buffer: true, stream: true } },
  tiff: { id: 'tiff',
    input: { file: true, buffer: true, stream: true },
    output: { file: true, buffer: false, stream: false } },
  raw: { id: 'raw',
    input: { file: false, buffer: false, stream: false },
    output: { file: false, buffer: true, stream: true } } }

queue

An EventEmitter that emits a change event when a task is either:

queued, waiting for libuv to provide a worker thread
complete

sharp.queue.on('change', function(queueLength) {
  console.log('Queue contains ' + queueLength + ' task(s)');
});

versions

An Object containing the version numbers of libvips and, on Linux, its dependencies.

console.log(sharp.versions);

Utilities

sharp.cache([options])

If options is provided, sets the limits of libvips' operation cache.

options.memory is the maximum memory in MB to use for this cache, with a default value of 50
options.files is the maximum number of files to hold open, with a default value of 20
options.items is the maximum number of operations to cache, with a default value of 100

options can also be a boolean, where true enables the default cache settings and false disables all caching.

Existing entries in the cache will be trimmed after any change in limits.

This method always returns cache statistics, useful for determining how much working memory is required for a particular task.

var stats = sharp.cache();

sharp.cache( { items: 200 } );
sharp.cache( { files: 0 } );
sharp.cache(false);

sharp.concurrency([threads])

threads, if provided, is the Number of threads libvips' should create for processing each image. The default value is the number of CPU cores. A value of 0 will reset to this default.

This method always returns the current concurrency.

var threads = sharp.concurrency(); // 4
sharp.concurrency(2); // 2
sharp.concurrency(0); // 4

The maximum number of images that can be processed in parallel is limited by libuv's UV_THREADPOOL_SIZE environment variable.

sharp.counters()

Provides access to internal task counters.

queue is the number of tasks this module has queued waiting for libuv to provide a worker thread from its pool.
process is the number of resize tasks currently being processed.

var counters = sharp.counters(); // { queue: 2, process: 4 }

sharp.simd([enable])

Requires libvips to have been compiled with liborc support

Improves the performance of resize, blur and sharpen operations by taking advantage of the SIMD vector unit of the CPU, e.g. Intel SSE and ARM NEON.

enable, if present, is a boolean where true enables and false disables the use of SIMD.

This method always returns the current state.

This feature is currently disabled by default but future versions may enable it by default.

When enabled, versions of liborc prior to 0.4.24 and versions of libvips prior to 8.2.0 have been known to crash under heavy load.

var simd = sharp.simd();
// simd is `true` if SIMD is currently enabled

var simd = sharp.simd(true);
// attempts to enable the use of SIMD, returning true if available

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API

Input

sharp([input], [options])

metadata([callback])

clone()

sequentialRead()

limitInputPixels(pixels)

Resizing

resize([width], [height], [options])

crop([option])

embed()

max()

min()

withoutEnlargement()

ignoreAspectRatio()

Operations

extract({ left: left, top: top, width: width, height: height })

trim([tolerance])

background(rgba)

flatten()

extend(extension)

negate()

rotate([angle])

flip()

flop()

blur([sigma])

convolve(kernel)

sharpen([sigma], [flat], [jagged])

threshold([threshold], [options])

gamma([gamma])

grayscale() / greyscale()

normalize() / normalise()

overlayWith(image, [options])

toColourspace(colourspace) / toColorspace(colorspace)

extractChannel(channel)

joinChannel(channels, [options])

bandbool(operation)

boolean(image, operation, [options])

Output

toFile(path, [callback])

toBuffer([callback])

jpeg()

png()

webp()

raw()

toFormat(format)

quality(quality)

progressive()

withMetadata([metadata])

tile(options)

withoutChromaSubsampling()

compressionLevel(compressionLevel)

withoutAdaptiveFiltering()

trellisQuantisation() / trellisQuantization()

overshootDeringing()

optimiseScans() / optimizeScans()

Attributes

format

queue

versions

Utilities

sharp.cache([options])

sharp.concurrency([threads])

sharp.counters()

sharp.simd([enable])

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