Input metadata

metadata

metadata([callback]) ⇒ Promise.<Object> | Sharp

Fast access to (uncached) image metadata without decoding any compressed pixel data.

This is read from the header of the input image. It does not take into consideration any operations to be applied to the output image, such as resize or rotate.

Dimensions in the response will respect the page and pages properties of the constructor parameters.

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
size: Total size of image in bytes, for Stream and Buffer input only
width: Number of pixels wide (EXIF orientation is not taken into consideration, see example below)
height: Number of pixels high (EXIF orientation is not taken into consideration, see example below)
space: Name of colour space interpretation e.g. srgb, rgb, cmyk, lab, b-w …
channels: Number of bands e.g. 3 for sRGB, 4 for CMYK
depth: Name of pixel depth format e.g. uchar, char, ushort, float …
density: Number of pixels per inch (DPI), if present
chromaSubsampling: String containing JPEG chroma subsampling, 4:2:0 or 4:4:4 for RGB, 4:2:0:4 or 4:4:4:4 for CMYK
isProgressive: Boolean indicating whether the image is interlaced using a progressive scan
isPalette: Boolean indicating whether the image is palette-based (GIF, PNG).
bitsPerSample: Number of bits per sample for each channel (GIF, PNG, HEIF).
pages: Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP
pageHeight: Number of pixels high each page in a multi-page image will be.
loop: Number of times to loop an animated image, zero refers to a continuous loop.
delay: Delay in ms between each page in an animated image, provided as an array of integers.
pagePrimary: Number of the primary page in a HEIF image
levels: Details of each level in a multi-level image provided as an array of objects, requires libvips compiled with support for OpenSlide
subifds: Number of Sub Image File Directories in an OME-TIFF image
background: Default background colour, if present, for PNG (bKGD) and GIF images
compression: The encoder used to compress an HEIF file, av1 (AVIF) or hevc (HEIC)
resolutionUnit: The unit of resolution (density), either inch or cm, 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
iptc: Buffer containing raw IPTC data, if present
xmp: Buffer containing raw XMP data, if present
tifftagPhotoshop: Buffer containing raw TIFFTAG_PHOTOSHOP data, if present
formatMagick: String containing format for images loaded via *magick
comments: Array of keyword/text pairs representing PNG text blocks, if present.

Param	Type	Description
[callback]	`function`	called with the arguments `(err, metadata)`

Example

const metadata = await sharp(input).metadata();

Example

const 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
  });

Example

// Get dimensions taking EXIF Orientation into account.
const { autoOrient } = await sharp(input).metadata();
const { width, height } = autoOrient;

stats

stats([callback]) ⇒ Promise.<Object>

Access to pixel-derived image statistics for every channel in the image. A Promise is returned when callback is not provided.

channels: Array of channel statistics for each channel in the image. Each channel statistic contains
- min (minimum value in the channel)
- max (maximum value in the channel)
- sum (sum of all values in a channel)
- squaresSum (sum of squared values in a channel)
- mean (mean of the values in a channel)
- stdev (standard deviation for the values in a channel)
- minX (x-coordinate of one of the pixel where the minimum lies)
- minY (y-coordinate of one of the pixel where the minimum lies)
- 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: Is the image fully opaque? Will be true if the image has no alpha channel or if every pixel is fully opaque.
entropy: Histogram-based estimation of greyscale entropy, discarding alpha channel if any.
sharpness: Estimation of greyscale sharpness based on the standard deviation of a Laplacian convolution, discarding alpha channel if any.
dominant: Object containing most dominant sRGB colour based on a 4096-bin 3D histogram.

Note: Statistics are derived from the original input image. Any operations performed on the image must first be written to a buffer in order to run stats on the result (see third example).

Param	Type	Description
[callback]	`function`	called with the arguments `(err, stats)`

Example

const image = sharp(inputJpg);
image
  .stats()
  .then(function(stats) {
     // stats contains the channel-wise statistics array and the isOpaque value
  });

Example

const { entropy, sharpness, dominant } = await sharp(input).stats();
const { r, g, b } = dominant;

Example

const image = sharp(input);
// store intermediate result
const part = await image.extract(region).toBuffer();
// create new instance to obtain statistics of extracted region
const stats = await sharp(part).stats();