@jsquash/jpeg

An easy experience for encoding and decoding JPEG images in the browser. Powered by WebAssembly ⚡️.

Uses the MozJPEG library.

A jSquash package. Codecs and supporting code derived from the Squoosh app.

Installation

npm install --save @jsquash/jpeg
# Or your favourite package manager alternative

Usage

Note: You will need to either manually include the wasm files from the codec directory or use a bundler like WebPack or Rollup to include them in your app/server.

decode(data: ArrayBuffer): Promise

Decodes JPEG binary ArrayBuffer to raw RGB image data.

data

Type: ArrayBuffer

Example

import { decode } from '@jsquash/jpeg';

const formEl = document.querySelector('form');
const formData = new FormData(formEl);
// Assuming user selected an input jpeg file
const imageData = await decode(await formData.get('image').arrayBuffer());

encode(data: ImageData, options?: EncodeOptions): Promise

Encodes raw RGB image data to JPEG format and resolves to an ArrayBuffer of binary data.

data

Type: ImageData

options

Type: Partial<EncodeOptions>

The MozJPEG encoder options for the output image. See default values.

Example

import { encode } from '@jsquash/jpeg';

async function loadImage(src) {
  const img = document.createElement('img');
  img.src = src;
  await new Promise(resolve => img.onload = resolve);
  const canvas = document.createElement('canvas');
  [canvas.width, canvas.height] = [img.width, img.height];
  const ctx = canvas.getContext('2d');
  ctx.drawImage(img, 0, 0);
  return ctx.getImageData(0, 0, img.width, img.height);
}

const rawImageData = await loadImage('/example.png');
const jpegBuffer = await encode(rawImageData);