A blazing-fast and compact JavaScript library dedicated to efficiently decoding JPEG images.

Using npm:

npm install jay-peg

Using yarn:

yarn add jay-peg

Use the decoder providing a JPEG data buffer as input.

import JPEG from 'jay-peg';

const jpegBuffer = /* your JPEG buffer here */;
const imageMarkers = JPEG.decoder(jpegBuffer);

console.log(imageMarkers);

The output consists of a structured array of image markers:

[
  {
    type: 65496,
    name: "SOI",
  },
  {
    type: 65505,
    name: "EXIF",
    length: 16382,
    identifier: "Exif\x00\x00",
    entries: [Object],
  },
  {
    type: 65499,
    name: "DAC",
    length: 132,
    tables: [[Object], [Object]],
  },
  // ... and so forth
  {
    type: 65497,
    name: "EOI",
  },
];

The decoder function accepts a JPEG buffer as its sole argument and returns an array of image markers.

• buffer: A Buffer or Uint8Array containing the JPEG image data.

An array of objects representing various markers found in the JPEG image.

Each ImageMarker object in the output array adheres to the following structure:

• type (Number): The marker type.
• name (String): The marker name.
• length (Number): The length of the marker data.
• Additional properties specific to certain marker types.

Performance is a key focus of `jay-peg``. In a benchmark test using a 2448×3264, 2.2MB JPEG image, the decoding speed was measured as follows:

Benchmarked: small:  x 11,597 ops/sec ±0.60% (95 runs sampled)
Benchmarked: medium:  x 11,219 ops/sec ±0.20% (98 runs sampled)
Benchmarked: large:  x 7,744 ops/sec ±0.27% (100 runs sampled)
Benchmarked: huge:  x 2,019 ops/sec ±0.36% (96 runs sampled)

It's worth noting that the performance is significantly improved on smaller and simpler images.

jay-peg is released under the MIT License