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, GIF, 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.

The caller is responsible for ensuring directory structures and permissions exist.

A Promise is returned when callback is not provided.

Returns: Promise.<Object> - - when no callback is provided
Throws:

• Error Invalid parameters

Param	Type	Description
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. When using the attention crop strategy also contains attentionX and attentionY, the focal point of the cropped region. May also contain textAutofitDpi (dpi the font was rendered at) if image was created from text.

Example

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

Example

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

toBuffer

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

Use toFormat or one of the format-specific functions such as jpeg, png etc. to set the output format.

If no explicit format is set, the output format will match the input image, except SVG input which becomes 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. May also contain textAutofitDpi (dpi the font was rendered at) if image was created from text.

A Promise is returned when callback is not provided.

Returns: Promise.<Buffer> - - when no callback is provided

Param	Type	Description
[options]	Object
[options.resolveWithObject]	boolean	Resolve the Promise with an Object containing data and info properties instead of resolving only with data.
[callback]	function

Example

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

Example

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

Example

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

Example

const { data, info } = await sharp('my-image.jpg')
  // output the raw pixels
  .raw()
  .toBuffer({ resolveWithObject: true });

// 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
const { width, height, channels } = info;
await sharp(pixelArray, { raw: { width, height, channels } })
  .toFile('my-changed-image.jpg');

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.

EXIF metadata is unsupported for TIFF output.

Throws:

• Error Invalid parameters

Param	Type	Default	Description
[options]	Object
[options.orientation]	number		value between 1 and 8, used to update the EXIF Orientation tag.
[options.icc]	string	"'srgb'"	Filesystem path to output ICC profile, relative to process.cwd(), defaults to built-in sRGB.
[options.exif]	Object.<Object>	{}	Object keyed by IFD0, IFD1 etc. of key/value string pairs to write as EXIF data.
[options.density]	number		Number of pixels per inch (DPI).

Example

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

Example

// Set "IFD0-Copyright" in output EXIF metadata
const data = await sharp(input)
  .withMetadata({
    exif: {
      IFD0: {
        Copyright: 'Wernham Hogg'
      }
    }
  })
  .toBuffer();

Example

// Set output metadata to 96 DPI
const data = await sharp(input)
  .withMetadata({ density: 96 })
  .toBuffer();

toFormat

Force output to a given format.

Throws:

• Error unsupported format or options

Param	Type	Description
format	string | Object	as a string or an Object with an 'id' attribute
options	Object	output options

Example

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

jpeg

Use these JPEG options for output image.

Throws:

• Error Invalid options

Param	Type	Default	Description
[options]	Object		output options
[options.quality]	number	80	quality, integer 1-100
[options.progressive]	boolean	false	use progressive (interlace) scan
[options.chromaSubsampling]	string	"'4:2:0'"	set to '4:4:4' to prevent chroma subsampling otherwise defaults to '4:2:0' chroma subsampling
[options.optimiseCoding]	boolean	true	optimise Huffman coding tables
[options.optimizeCoding]	boolean	true	alternative spelling of optimiseCoding
[options.mozjpeg]	boolean	false	use mozjpeg defaults, equivalent to { trellisQuantisation: true, overshootDeringing: true, optimiseScans: true, quantisationTable: 3 }
[options.trellisQuantisation]	boolean	false	apply trellis quantisation
[options.overshootDeringing]	boolean	false	apply overshoot deringing
[options.optimiseScans]	boolean	false	optimise progressive scans, forces progressive
[options.optimizeScans]	boolean	false	alternative spelling of optimiseScans
[options.quantisationTable]	number	0	quantization table to use, integer 0-8
[options.quantizationTable]	number	0	alternative spelling of quantisationTable
[options.force]	boolean	true	force JPEG output, otherwise attempt to use input format

Example

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

Example

// Use mozjpeg to reduce output JPEG file size (slower)
const data = await sharp(input)
  .jpeg({ mozjpeg: true })
  .toBuffer();

png

Use these PNG options for output image.

By default, PNG output is 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. Set palette to true for slower, indexed PNG output.

Throws:

• Error Invalid options

Param	Type	Default	Description
[options]	Object
[options.progressive]	boolean	false	use progressive (interlace) scan
[options.compressionLevel]	number	6	zlib compression level, 0 (fastest, largest) to 9 (slowest, smallest)
[options.adaptiveFiltering]	boolean	false	use adaptive row filtering
[options.palette]	boolean	false	quantise to a palette-based image with alpha transparency support
[options.quality]	number	100	use the lowest number of colours needed to achieve given quality, sets palette to true
[options.effort]	number	7	CPU effort, between 1 (fastest) and 10 (slowest), sets palette to true
[options.colours]	number	256	maximum number of palette entries, sets palette to true
[options.colors]	number	256	alternative spelling of options.colours, sets palette to true
[options.dither]	number	1.0	level of Floyd-Steinberg error diffusion, sets palette to true
[options.force]	boolean	true	force PNG output, otherwise attempt to use input format

Example

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

Example

// Convert any input to indexed PNG output (slower)
const data = await sharp(input)
  .png({ palette: true })
  .toBuffer();

webp

Use these WebP options for output image.

Throws:

• Error Invalid options

Param	Type	Default	Description
[options]	Object		output options
[options.quality]	number	80	quality, integer 1-100
[options.alphaQuality]	number	100	quality of alpha layer, integer 0-100
[options.lossless]	boolean	false	use lossless compression mode
[options.nearLossless]	boolean	false	use near_lossless compression mode
[options.smartSubsample]	boolean	false	use high quality chroma subsampling
[options.effort]	number	4	CPU effort, between 0 (fastest) and 6 (slowest)
[options.loop]	number	0	number of animation iterations, use 0 for infinite animation
[options.delay]	number | Array.<number>		delay(s) between animation frames (in milliseconds)
[options.minSize]	boolean	false	prevent use of animation key frames to minimise file size (slow)
[options.mixed]	boolean	false	allow mixture of lossy and lossless animation frames (slow)
[options.force]	boolean	true	force WebP output, otherwise attempt to use input format

Example

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

Example

// Optimise the file size of an animated WebP
const outputWebp = await sharp(inputWebp, { animated: true })
  .webp({ effort: 6 })
  .toBuffer();

gif

Use these GIF options for the output image.

The first entry in the palette is reserved for transparency.

The palette of the input image will be re-used if possible.

Throws:

• Error Invalid options

Since: 0.30.0

Param	Type	Default	Description
[options]	Object		output options
[options.reuse]	boolean	true	re-use existing palette, otherwise generate new (slow)
[options.progressive]	boolean	false	use progressive (interlace) scan
[options.colours]	number	256	maximum number of palette entries, including transparency, between 2 and 256
[options.colors]	number	256	alternative spelling of options.colours
[options.effort]	number	7	CPU effort, between 1 (fastest) and 10 (slowest)
[options.dither]	number	1.0	level of Floyd-Steinberg error diffusion, between 0 (least) and 1 (most)
[options.interFrameMaxError]	number	0	maximum inter-frame error for transparency, between 0 (lossless) and 32
[options.interPaletteMaxError]	number	3	maximum inter-palette error for palette reuse, between 0 and 256
[options.loop]	number	0	number of animation iterations, use 0 for infinite animation
[options.delay]	number | Array.<number>		delay(s) between animation frames (in milliseconds)
[options.force]	boolean	true	force GIF output, otherwise attempt to use input format

Example

// Convert PNG to GIF
await sharp(pngBuffer)
  .gif()
  .toBuffer();

Example

// Convert animated WebP to animated GIF
await sharp('animated.webp', { animated: true })
  .toFile('animated.gif');

Example

// Create a 128x128, cropped, non-dithered, animated thumbnail of an animated GIF
const out = await sharp('in.gif', { animated: true })
  .resize({ width: 128, height: 128 })
  .gif({ dither: 0 })
  .toBuffer();

Example

// Lossy file size reduction of animated GIF
await sharp('in.gif', { animated: true })
  .gif({ interFrameMaxError: 8 })
  .toFile('optim.gif');

tiff

Use these TIFF options for output image.

The density can be set in pixels/inch via withMetadata instead of providing xres and yres in pixels/mm.

Throws:

• Error Invalid options

Param	Type	Default	Description
[options]	Object		output options
[options.quality]	number	80	quality, integer 1-100
[options.force]	boolean	true	force TIFF output, otherwise attempt to use input format
[options.compression]	string	"'jpeg'"	compression options: none, jpeg, deflate, packbits, ccittfax4, lzw, webp, zstd, jp2k
[options.predictor]	string	"'horizontal'"	compression predictor options: none, horizontal, float
[options.pyramid]	boolean	false	write an image pyramid
[options.tile]	boolean	false	write a tiled tiff
[options.tileWidth]	number	256	horizontal tile size
[options.tileHeight]	number	256	vertical tile size
[options.xres]	number	1.0	horizontal resolution in pixels/mm
[options.yres]	number	1.0	vertical resolution in pixels/mm
[options.resolutionUnit]	string	"'inch'"	resolution unit options: inch, cm
[options.bitdepth]	number	8	reduce bitdepth to 1, 2 or 4 bit

Example

// 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 => { ... });

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.

AVIF image sequences are not supported.

Throws:

• Error Invalid options

Since: 0.27.0

Param	Type	Default	Description
[options]	Object		output options
[options.quality]	number	50	quality, integer 1-100
[options.lossless]	boolean	false	use lossless compression
[options.effort]	number	4	CPU effort, between 0 (fastest) and 9 (slowest)
[options.chromaSubsampling]	string	"'4:4:4'"	set to '4:2:0' to use chroma subsampling

Example

const data = await sharp(input)
  .avif({ effort: 2 })
  .toBuffer();

Example

const data = await sharp(input)
  .avif({ lossless: true })
  .toBuffer();

heif

Use these HEIF options for output image.

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

Throws:

• Error Invalid options

Since: 0.23.0

Param	Type	Default	Description
[options]	Object		output options
[options.quality]	number	50	quality, integer 1-100
[options.compression]	string	"'av1'"	compression format: av1, hevc
[options.lossless]	boolean	false	use lossless compression
[options.effort]	number	4	CPU effort, between 0 (fastest) and 9 (slowest)
[options.chromaSubsampling]	string	"'4:4:4'"	set to '4:2:0' to use chroma subsampling

Example

const data = await sharp(input)
  .heif({ compression: 'hevc' })
  .toBuffer();

jxl

Use these JPEG-XL (JXL) options for output image.

This feature is experimental, please do not use in production systems.

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

Image metadata (EXIF, XMP) is unsupported.

Throws:

• Error Invalid options

Since: 0.31.3

Param	Type	Default	Description
[options]	Object		output options
[options.distance]	number	1.0	maximum encoding error, between 0 (highest quality) and 15 (lowest quality)
[options.quality]	number		calculate distance based on JPEG-like quality, between 1 and 100, overrides distance if specified
[options.decodingTier]	number	0	target decode speed tier, between 0 (highest quality) and 4 (lowest quality)
[options.lossless]	boolean	false	use lossless compression
[options.effort]	number	7	CPU effort, between 3 (fastest) and 9 (slowest)

raw

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

Throws:

• Error Invalid options

Param	Type	Default	Description
[options]	Object		output options
[options.depth]	string	"'uchar'"	bit depth, one of: char, uchar (default), short, ushort, int, uint, float, complex, double, dpcomplex

Example

// Extract raw, unsigned 8-bit RGB pixel data from JPEG input
const { data, info } = await sharp('input.jpg')
  .raw()
  .toBuffer({ resolveWithObject: true });

Example

// Extract alpha channel as raw, unsigned 16-bit pixel data from PNG input
const data = await sharp('input.png')
  .ensureAlpha()
  .extractChannel(3)
  .toColourspace('b-w')
  .raw({ depth: 'ushort' })
  .toBuffer();

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.

The container will be set to zip when the output is a Buffer or Stream, otherwise it will default to fs.

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

Throws:

• Error Invalid parameters

Param	Type	Default	Description
[options]	Object
[options.size]	number	256	tile size in pixels, a value between 1 and 8192.
[options.overlap]	number	0	tile overlap in pixels, a value between 0 and 8192.
[options.angle]	number	0	tile angle of rotation, must be a multiple of 90.
[options.background]	string | Object	"{r: 255, g: 255, b: 255, alpha: 1}"	background colour, parsed by the color module, defaults to white without transparency.
[options.depth]	string		how deep to make the pyramid, possible values are onepixel, onetile or one, default based on layout.
[options.skipBlanks]	number	-1	threshold to skip tile generation, a value 0 - 255 for 8-bit images or 0 - 65535 for 16-bit images
[options.container]	string	"'fs'"	tile container, with value fs (filesystem) or zip (compressed file).
[options.layout]	string	"'dz'"	filesystem layout, possible values are dz, iiif, iiif3, zoomify or google.
[options.centre]	boolean	false	centre image in tile.
[options.center]	boolean	false	alternative spelling of centre.
[options.id]	string	"'https://example.com/iiif'"	when layout is iiif/iiif3, sets the @id/id attribute of info.json
[options.basename]	string		the name of the directory within the zip file when container is zip.

Example

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

Example

const zipFileWithTiles = await sharp(input)
  .tile({ basename: "tiles" })
  .toBuffer();

Example

const iiififier = sharp().tile({ layout: "iiif" });
readableStream
  .pipe(iiififier)
  .pipe(writeableStream);

timeout

Set a timeout for processing, in seconds. Use a value of zero to continue processing indefinitely, the default behaviour.

The clock starts when libvips opens an input image for processing. Time spent waiting for a libuv thread to become available is not included.

Since: 0.29.2

Param	Type	Description
options	Object
options.seconds	number	Number of seconds after which processing will be stopped

Example

// Ensure processing takes no longer than 3 seconds
try {
  const data = await sharp(input)
    .blur(1000)
    .timeout({ seconds: 3 })
    .toBuffer();
} catch (err) {
  if (err.message.includes('timeout')) { ... }
}