sharp/docs/api-constructor.md

Sharp

Constructor factory to create an instance of sharp, to which further methods are chained.

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

Non-critical problems encountered during processing are emitted as warning events.

Implements the stream.Duplex class.

Parameters

• input (Buffer | Uint8Array | Uint8ClampedArray | Int8Array | Uint16Array | Int16Array | Uint32Array | Int32Array | Float32Array | Float64Array | string)? if present, can be a Buffer / Uint8Array / Uint8ClampedArray containing JPEG, PNG, WebP, AVIF, GIF, SVG or TIFF image data, or a TypedArray containing raw pixel image data, or a String containing the filesystem path to an JPEG, PNG, WebP, AVIF, GIF, SVG or TIFF image file. JPEG, PNG, WebP, AVIF, GIF, SVG, TIFF or raw pixel image data can be streamed into the object when not present.

• options Object? if present, is an Object with optional attributes.

  • options.failOn string level of sensitivity to invalid images, one of (in order of sensitivity): 'none' (least), 'truncated', 'error' or 'warning' (most), highers level imply lower levels. (optional, default 'warning')

  • options.limitInputPixels (number | boolean) Do not process input images where the number of pixels (width x height) exceeds this limit. Assumes image dimensions contained in the input metadata can be trusted. An integral Number of pixels, zero or false to remove limit, true to use default limit of 268402689 (0x3FFF x 0x3FFF). (optional, default 268402689)

  • options.unlimited boolean Set this to true to remove safety features that help prevent memory exhaustion (JPEG, PNG, SVG, HEIF). (optional, default false)

  • options.sequentialRead boolean Set this to true to use sequential rather than random access where possible. This can reduce memory usage and might improve performance on some systems. (optional, default false)

  • options.density number number representing the DPI for vector images in the range 1 to 100000. (optional, default 72)

  • options.pages number number of pages to extract for multi-page input (GIF, WebP, AVIF, TIFF, PDF), use -1 for all pages. (optional, default 1)

  • options.page number page number to start extracting from for multi-page input (GIF, WebP, AVIF, TIFF, PDF), zero based. (optional, default 0)

  • options.subifd number subIFD (Sub Image File Directory) to extract for OME-TIFF, defaults to main image. (optional, default -1)

  • options.level number level to extract from a multi-level input (OpenSlide), zero based. (optional, default 0)

  • options.animated boolean Set to true to read all frames/pages of an animated image (equivalent of setting pages to -1). (optional, default false)

  • options.raw Object? describes raw pixel input image data. See raw() for pixel ordering.

    • options.raw.width number? integral number of pixels wide.
    • options.raw.height number? integral number of pixels high.
    • options.raw.channels number? integral number of channels, between 1 and 4.
    • options.raw.premultiplied boolean? specifies that the raw input has already been premultiplied, set to true to avoid sharp premultiplying the image. (optional, default false)

  • options.create Object? describes a new image to be created.

    • options.create.width number? integral number of pixels wide.

    • options.create.height number? integral number of pixels high.

    • options.create.channels number? integral number of channels, either 3 (RGB) or 4 (RGBA).

    • options.create.background (string | Object)? parsed by the color module to extract values for red, green, blue and alpha.

    • options.create.noise Object? describes a noise to be created.

      • options.create.noise.type string? type of generated noise, currently only gaussian is supported.
      • options.create.noise.mean number? mean of pixels in generated noise.
      • options.create.noise.sigma number? standard deviation of pixels in generated noise.

  • options.text Object? describes a new text image to be created.

    • options.text.text string? text to render as a UTF-8 string. It can contain Pango markup, for example <i>Le</i>Monde.
    • options.text.font string? font name to render with.
    • options.text.fontfile string? absolute filesystem path to a font file that can be used by font.
    • options.text.width number integral number of pixels to word-wrap at. Lines of text wider than this will be broken at word boundaries. (optional, default 0)
    • options.text.height number integral number of pixels high. When defined, dpi will be ignored and the text will automatically fit the pixel resolution defined by width and height. Will be ignored if width is not specified or set to 0. (optional, default 0)
    • options.text.align string text alignment ('left', 'centre', 'center', 'right'). (optional, default 'left')
    • options.text.justify boolean set this to true to apply justification to the text. (optional, default false)
    • options.text.dpi number the resolution (size) at which to render the text. Does not take effect if height is specified. (optional, default 72)
    • options.text.rgba boolean set this to true to enable RGBA output. This is useful for colour emoji rendering, or support for pango markup features like <span foreground="red">Red!</span>. (optional, default false)
    • options.text.spacing number text line height in points. Will use the font line height if none is specified. (optional, default 0)

Examples

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);

// Create a blank 300x200 PNG image of semi-transluent red pixels
sharp({
  create: {
    width: 300,
    height: 200,
    channels: 4,
    background: { r: 255, g: 0, b: 0, alpha: 0.5 }
  }
})
.png()
.toBuffer()
.then( ... );

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

// Read a raw array of pixels and save it to a png
const input = Uint8Array.from([255, 255, 255, 0, 0, 0]); // or Uint8ClampedArray
const image = sharp(input, {
  // because the input does not contain its dimensions or how many channels it has
  // we need to specify it in the constructor options
  raw: {
    width: 2,
    height: 1,
    channels: 3
  }
});
await image.toFile('my-two-pixels.png');

// Generate RGB Gaussian noise
await sharp({
  create: {
    width: 300,
    height: 200,
    channels: 3,
    noise: {
      type: 'gaussian',
      mean: 128,
      sigma: 30
    }
 }
}).toFile('noise.png');

// Generate an image from text
await sharp({
  text: {
    text: 'Hello, world!',
    width: 400, // max width
    height: 300 // max height
  }
}).toFile('text_bw.png');

// Generate an rgba image from text using pango markup and font
await sharp({
  text: {
    text: '<span foreground="red">Red!</span><span background="cyan">blue</span>',
    font: 'sans',
    rgba: true,
    dpi: 300
  }
}).toFile('text_rgba.png');

• Throws Error Invalid parameters

Returns Sharp

clone

Take a "snapshot" of the Sharp 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.

Examples

const 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

// Create a pipeline that will download an image, resize it and format it to different files
// Using Promises to know when the pipeline is complete
const fs = require("fs");
const got = require("got");
const sharpStream = sharp({ failOn: 'none' });

const promises = [];

promises.push(
  sharpStream
    .clone()
    .jpeg({ quality: 100 })
    .toFile("originalFile.jpg")
);

promises.push(
  sharpStream
    .clone()
    .resize({ width: 500 })
    .jpeg({ quality: 80 })
    .toFile("optimized-500.jpg")
);

promises.push(
  sharpStream
    .clone()
    .resize({ width: 500 })
    .webp({ quality: 80 })
    .toFile("optimized-500.webp")
);

// https://github.com/sindresorhus/got/blob/main/documentation/3-streams.md
got.stream("https://www.example.com/some-file.jpg").pipe(sharpStream);

Promise.all(promises)
  .then(res => { console.log("Done!", res); })
  .catch(err => {
    console.error("Error processing files, let's clean it up", err);
    try {
      fs.unlinkSync("originalFile.jpg");
      fs.unlinkSync("optimized-500.jpg");
      fs.unlinkSync("optimized-500.webp");
    } catch (e) {}
  });

Returns Sharp