jay-peg

Overview

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

Installation

Using npm:

``bash
npm install jay-peg
`

Using yarn:

`bash
yarn add jay-peg
`

Usage

Use the decoder providing a JPEG data buffer as input.

`javascript
import JPEG from 'jay-peg';

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

console.log(imageMarkers);
`

Example Output

The output consists of a structured array of image markers:

`javascript
[
{
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",
},
];
`

API

$3

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

#### Parameters

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

#### Returns

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

$3

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

Performance is a key focus of jay-peg. 4 sizes of images were benchmarked:

- small: 300 × 150, 8KB image
- medium: 800 × 600, 70KB image
- large: 1920 × 1080, 332KB image
- huge: 2448×3264, 2.2MB image

For each of these, the decoding speed was measured as follows:

`
Benchmarked: small: x 13,393 ops/sec ±4.77% (96 runs sampled)
Benchmarked: medium: x 12,894 ops/sec ±0.10% (99 runs sampled)
Benchmarked: large: x 9,241 ops/sec ±0.25% (99 runs sampled)
Benchmarked: huge: x 2,672 ops/sec ±0.12% (100 runs sampled)
`

_Measures were taken in an MacBook Air 2024, Apple M3 w/16GB of RAM._

License

jay-peg` is released under the MIT License