sharp/docs/api-output.md

toFile

Write output image data to a file.

If an explicit output format is not selected, it will be inferred from the extension, with JPEG, PNG, WebP, AVIF, TIFF, DZI, and libvips' V format supported. Note that raw pixel data is only supported for buffer output.

By default all metadata will be removed, which includes EXIF-based orientation. See withMetadata for control over this.

A Promise is returned when callback is not provided.

Parameters

• fileOut string the path to write the image data to.
• callback Function? called on completion with two arguments (err, info). info contains the output image format, size (bytes), width, height, channels and premultiplied (indicating if premultiplication was used). When using a crop strategy also contains cropOffsetLeft and cropOffsetTop.

Examples

sharp(input)
  .toFile('output.png', (err, info) => { ... });

sharp(input)
  .toFile('output.png')
  .then(info => { ... })
  .catch(err => { ... });

• Throws Error Invalid parameters

Returns Promise<Object> when no callback is provided

toBuffer

Write output to a Buffer. JPEG, PNG, WebP, AVIF, TIFF and raw pixel data output are supported.

If no explicit format is set, the output format will match the input image, except GIF and SVG input which become PNG output.

By default all metadata will be removed, which includes EXIF-based orientation. See withMetadata for control over this.

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

• err is an error, if any.
• data is the output image data.
• info contains the output image format, size (bytes), width, height, channels and premultiplied (indicating if premultiplication was used). When using a crop strategy also contains cropOffsetLeft and cropOffsetTop.

A Promise is returned when callback is not provided.

Parameters

• options Object?
  • options.resolveWithObject boolean? Resolve the Promise with an Object containing data and info properties instead of resolving only with data.
• callback Function?

Examples

sharp(input)
  .toBuffer((err, data, info) => { ... });

sharp(input)
  .toBuffer()
  .then(data => { ... })
  .catch(err => { ... });

sharp(input)
  .toBuffer({ resolveWithObject: true })
  .then(({ data, info }) => { ... })
  .catch(err => { ... });

const data = await sharp('my-image.jpg')
  // output the raw pixels
  .raw()
  .toBuffer();

// create a more type safe way to work with the raw pixel data
// this will not copy the data, instead it will change `data`s underlying ArrayBuffer
// so `data` and `pixelArray` point to the same memory location
const pixelArray = new Uint8ClampedArray(data.buffer);

// When you are done changing the pixelArray, sharp takes the `pixelArray` as an input
await sharp(pixelArray).toFile('my-changed-image.jpg');

Returns Promise<Buffer> when no callback is provided

withMetadata

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

The default behaviour, when withMetadata is not used, is to convert to the device-independent sRGB colour space and strip all metadata, including the removal of any ICC profile.

Parameters

• options Object?
  • options.orientation number? value between 1 and 8, used to update the EXIF Orientation tag.
  • options.icc string? filesystem path to output ICC profile, defaults to sRGB.

Examples

sharp('input.jpg')
  .withMetadata()
  .toFile('output-with-metadata.jpg')
  .then(info => { ... });

• Throws Error Invalid parameters

Returns Sharp

toFormat

Force output to a given format.

Parameters

• format (string | Object) as a string or an Object with an 'id' attribute
• options Object output options

Examples

// Convert any input to PNG output
const data = await sharp(input)
  .toFormat('png')
  .toBuffer();

• Throws Error unsupported format or options

Returns Sharp

jpeg

Use these JPEG options for output image.

Some of these options require the use of a globally-installed libvips compiled with support for mozjpeg.

Parameters

• options Object? output options
  • options.quality number quality, integer 1-100 (optional, default 80)
  • options.progressive boolean use progressive (interlace) scan (optional, default false)
  • options.chromaSubsampling string set to '4:4:4' to prevent chroma subsampling otherwise defaults to '4:2:0' chroma subsampling (optional, default '4:2:0')
  • options.optimiseCoding boolean optimise Huffman coding tables (optional, default true)
  • options.optimizeCoding boolean alternative spelling of optimiseCoding (optional, default true)
  • options.trellisQuantisation boolean apply trellis quantisation, requires libvips compiled with support for mozjpeg (optional, default false)
  • options.overshootDeringing boolean apply overshoot deringing, requires libvips compiled with support for mozjpeg (optional, default false)
  • options.optimiseScans boolean optimise progressive scans, forces progressive, requires libvips compiled with support for mozjpeg (optional, default false)
  • options.optimizeScans boolean alternative spelling of optimiseScans, requires libvips compiled with support for mozjpeg (optional, default false)
  • options.quantisationTable number quantization table to use, integer 0-8, requires libvips compiled with support for mozjpeg (optional, default 0)
  • options.quantizationTable number alternative spelling of quantisationTable, requires libvips compiled with support for mozjpeg (optional, default 0)
  • options.force boolean force JPEG output, otherwise attempt to use input format (optional, default true)

Examples

// Convert any input to very high quality JPEG output
const data = await sharp(input)
  .jpeg({
    quality: 100,
    chromaSubsampling: '4:4:4'
  })
  .toBuffer();

• Throws Error Invalid options

Returns Sharp

png

Use these PNG options for output image.

PNG output is always full colour at 8 or 16 bits per pixel. Indexed PNG input at 1, 2 or 4 bits per pixel is converted to 8 bits per pixel.

Some of these options require the use of a globally-installed libvips compiled with support for libimagequant (GPL).

Parameters

• options Object?
  • options.progressive boolean use progressive (interlace) scan (optional, default false)
  • options.compressionLevel number zlib compression level, 0-9 (optional, default 9)
  • options.adaptiveFiltering boolean use adaptive row filtering (optional, default false)
  • options.palette boolean quantise to a palette-based image with alpha transparency support, requires libvips compiled with support for libimagequant (optional, default false)
  • options.quality number use the lowest number of colours needed to achieve given quality, sets palette to true, requires libvips compiled with support for libimagequant (optional, default 100)
  • options.colours number maximum number of palette entries, sets palette to true, requires libvips compiled with support for libimagequant (optional, default 256)
  • options.colors number alternative spelling of options.colours, sets palette to true, requires libvips compiled with support for libimagequant (optional, default 256)
  • options.dither number level of Floyd-Steinberg error diffusion, sets palette to true, requires libvips compiled with support for libimagequant (optional, default 1.0)
  • options.force boolean force PNG output, otherwise attempt to use input format (optional, default true)

Examples

// Convert any input to PNG output
const data = await sharp(input)
  .png()
  .toBuffer();

• Throws Error Invalid options

Returns Sharp

webp

Use these WebP options for output image.

Parameters

• options Object? output options
  • options.quality number quality, integer 1-100 (optional, default 80)
  • options.alphaQuality number quality of alpha layer, integer 0-100 (optional, default 100)
  • options.lossless boolean use lossless compression mode (optional, default false)
  • options.nearLossless boolean use near_lossless compression mode (optional, default false)
  • options.smartSubsample boolean use high quality chroma subsampling (optional, default false)
  • options.reductionEffort number level of CPU effort to reduce file size, integer 0-6 (optional, default 4)
  • options.pageHeight number? page height for animated output
  • options.loop number number of animation iterations, use 0 for infinite animation (optional, default 0)
  • options.delay Array<number>? list of delays between animation frames (in milliseconds)
  • options.force boolean force WebP output, otherwise attempt to use input format (optional, default true)

Examples

// Convert any input to lossless WebP output
const data = await sharp(input)
  .webp({ lossless: true })
  .toBuffer();

• Throws Error Invalid options

Returns Sharp

gif

Use these GIF options for output image.

Requires libvips compiled with support for ImageMagick or GraphicsMagick. The prebuilt binaries do not include this - see installing a custom libvips.

Parameters

• options Object? output options

  • options.pageHeight number? page height for animated output
  • options.loop number number of animation iterations, use 0 for infinite animation (optional, default 0)
  • options.delay Array<number>? list of delays between animation frames (in milliseconds)
  • options.force boolean force GIF output, otherwise attempt to use input format (optional, default true)

• Throws Error Invalid options

Returns Sharp

tiff

Use these TIFF options for output image.

Parameters

• options Object? output options
  • options.quality number quality, integer 1-100 (optional, default 80)
  • options.force boolean force TIFF output, otherwise attempt to use input format (optional, default true)
  • options.compression boolean compression options: lzw, deflate, jpeg, ccittfax4 (optional, default 'jpeg')
  • options.predictor boolean compression predictor options: none, horizontal, float (optional, default 'horizontal')
  • options.pyramid boolean write an image pyramid (optional, default false)
  • options.tile boolean write a tiled tiff (optional, default false)
  • options.tileWidth boolean horizontal tile size (optional, default 256)
  • options.tileHeight boolean vertical tile size (optional, default 256)
  • options.xres number horizontal resolution in pixels/mm (optional, default 1.0)
  • options.yres number vertical resolution in pixels/mm (optional, default 1.0)
  • options.bitdepth boolean reduce bitdepth to 1, 2 or 4 bit (optional, default 8)

Examples

// Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
sharp('input.svg')
  .tiff({
    compression: 'lzw',
    bitdepth: 1
  })
  .toFile('1-bpp-output.tiff')
  .then(info => { ... });

• Throws Error Invalid options

Returns Sharp

avif

Use these AVIF options for output image.

Whilst it is possible to create AVIF images smaller than 16x16 pixels, most web browsers do not display these properly.

Parameters

• options Object? output options

  • options.quality number quality, integer 1-100 (optional, default 50)
  • options.lossless boolean use lossless compression (optional, default false)
  • options.speed boolean CPU effort vs file size, 0 (slowest/smallest) to 8 (fastest/largest) (optional, default 5)

• Throws Error Invalid options

Returns Sharp

Meta

• since: 0.27.0

heif

Use these HEIF options for output image.

Support for patent-encumbered HEIC images requires the use of a globally-installed libvips compiled with support for libheif, libde265 and x265.

Parameters

• options Object? output options

  • options.quality number quality, integer 1-100 (optional, default 50)
  • options.compression boolean compression format: av1, hevc (optional, default 'av1')
  • options.lossless boolean use lossless compression (optional, default false)
  • options.speed boolean CPU effort vs file size, 0 (slowest/smallest) to 8 (fastest/largest) (optional, default 5)

• Throws Error Invalid options

Returns Sharp

Meta

• since: 0.23.0

raw

Force output to be raw, uncompressed, 8-bit unsigned integer (unit8) pixel data. Pixel ordering is left-to-right, top-to-bottom, without padding. Channel ordering will be RGB or RGBA for non-greyscale colourspaces.

Examples

// Extract raw RGB pixel data from JPEG input
const { data, info } = await sharp('input.jpg')
  .raw()
  .toBuffer({ resolveWithObject: true });

// Extract alpha channel as raw pixel data from PNG input
const data = await sharp('input.png')
  .ensureAlpha()
  .extractChannel(3)
  .toColourspace('b-w')
  .raw()
  .toBuffer();

Returns Sharp

tile

Use tile-based deep zoom (image pyramid) output. Set the format and options for tile images via the toFormat, jpeg, png or webp functions. Use a .zip or .szi file extension with toFile to write to a compressed archive file format.

Warning: multiple sharp instances concurrently producing tile output can expose a possible race condition in some versions of libgsf.

Parameters

• options Object?
  • options.size number tile size in pixels, a value between 1 and 8192. (optional, default 256)
  • options.overlap number tile overlap in pixels, a value between 0 and 8192. (optional, default 0)
  • options.angle number tile angle of rotation, must be a multiple of 90. (optional, default 0)
  • options.background (string | Object) background colour, parsed by the color module, defaults to white without transparency. (optional, default {r:255,g:255,b:255,alpha:1})
  • options.depth string? how deep to make the pyramid, possible values are onepixel, onetile or one, default based on layout.
  • options.skipBlanks number threshold to skip tile generation, a value 0 - 255 for 8-bit images or 0 - 65535 for 16-bit images (optional, default -1)
  • options.container string tile container, with value fs (filesystem) or zip (compressed file). (optional, default 'fs')
  • options.layout string filesystem layout, possible values are dz, iiif, zoomify or google. (optional, default 'dz')
  • options.centre boolean centre image in tile. (optional, default false)
  • options.center boolean alternative spelling of centre. (optional, default false)

Examples

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

• Throws Error Invalid parameters

Returns Sharp