PureJsImage · JPEG XL

Exact JPEG recompression

Transfer eligible grayscale or color JPEG coefficients to JPEG XL and reconstruct the original JPEG bytes.

These tools use the current repository build. Repository functionality may be newer than the npm release. Static lossy encoding is qualified; lossy animation remains Experimental.

Interactive workbench

Encode pixels, inspect JPEG XL, or transcode JPEG

Loading a deterministic JPEG sample…

Open

Local JPEG or JPEG XL

Require JPEG XL output to be smaller

Pixel-lossless encode preserves supported decoded samples. The exact JPEG path transfers quantized DCT coefficients and reconstruction metadata without decoding RGB first. The size requirement is off unless you select it.

Synchronized preview zoom

Source

Decoded preview

Result summary

Status: Waiting

Inspection and execution evidence

Waiting for local inspection.

Browser API

import { transcodeJpegToJpegXl, reconstructJpegFromJpegXl } from 'purejsimage/jpegxl'
const bytes = new Uint8Array(await file.arrayBuffer())
const jxl = await transcodeJpegToJpegXl(bytes, {reconstruction: 'required', onlyIfSmaller: false})
const original = await reconstructJpegFromJpegXl(jxl.data)
// Exact mode verifies every original byte before succeeding.

Color JPEG: 320 × 240 four-color pattern from web-platform-tests contributors, generated with Squoosh MozJPEG (BSD 3-Clause). Grayscale JPEG and transparent PNG: generated repository fixtures (MIT). WPT license. No camera or personal data.