@catlabtech/webcvt-image-jsquash-mozjpeg

High-quality JPEG decode/encode backend for webcvt, wrapping @jsquash/jpeg (MozJPEG in WebAssembly).

MozJPEG produces smaller JPEGs than the browser's built-in encoder (trellis quantisation, progressive coding) — choose this backend when output size matters.

Overlaps image-canvas

Both this backend and @catlabtech/webcvt-image-canvas handle image/jpeg. Register only one per registry: this one for best compression, image-canvas for the zero-dependency / hardware-accelerated path.

Installation

npm i @catlabtech/webcvt-image-jsquash-mozjpeg @jsquash/jpeg

Supported conversions

Input	Output
JPEG	JPEG (recompress), PNG, WebP
PNG, WebP	JPEG

Cross-format paths use a canvas pixel-bridge (OffscreenCanvas). JPEG→JPEG works anywhere.

Usage

import { registerMozjpegBackend } from '@catlabtech/webcvt-image-jsquash-mozjpeg';

registerMozjpegBackend(undefined, { encode: { quality: 80, progressive: true } });

Free functions decodeMozjpeg / encodeMozjpeg are also exported.

Encode options

{
  quality?: number;       // 0–100, default 75
  progressive?: boolean;  // default false
  baseline?: boolean;     // default false
}

Notes

• The wasm codec needs script-src 'wasm-unsafe-eval'.
• Security caps: 256 MiB max input, 25 MP max image (typed errors on violation).

Source

packages/image-jsquash-mozjpeg/src