@cornerstonejs/codec-libjxl

JavaScript/WebAssembly build of libjxl with separate decoder and encoder modules for JPEG XL DICOM images.

Installing

Using npm:

npm install @cornerstonejs/codec-libjxl

Using yarn:

yarn add @cornerstonejs/codec-libjxl

Usage

The package exports separate JavaScript loaders and WASM binaries for decoding and encoding:

• @cornerstonejs/codec-libjxl/decodewasmjs
• @cornerstonejs/codec-libjxl/decodewasm
• @cornerstonejs/codec-libjxl/encodewasmjs
• @cornerstonejs/codec-libjxl/encodewasm

Decoder

import createJpegXLDecoder from '@cornerstonejs/codec-libjxl/decodewasmjs';

const codec = await createJpegXLDecoder();
const decoder = new codec.JpegXLDecoder();

decoder.getEncodedBuffer(bitstream.length).set(bitstream);
decoder.decode();

const frameInfo = decoder.getFrameInfo();
const decodedPixels = decoder.getDecodedBuffer();

Encoder

import createJpegXLEncoder from '@cornerstonejs/codec-libjxl/encodewasmjs';

const codec = await createJpegXLEncoder();
const encoder = new codec.JpegXLEncoder();
const frameInfo = {
  width,
  height,
  bitsPerSample,
  componentCount,
  isSigned: false,
};

encoder.getDecodedBuffer(frameInfo).set(decodedPixels);
encoder.setLossless(true);
encoder.encode();

const bitstream = encoder.getEncodedBuffer();

The encoder accepts greyscale samples with one channel or RGB samples with three channels at bit depths from 1 to 16. Copy returned buffer views before the next operation or before calling releaseBuffers().

Building

This project uses a Git submodule for libjxl. Initialize the submodules from the repository root:

git submodule update --init --recursive

An activated Emscripten SDK is required. Build both WASM modules with:

cd packages/libjxl
yarn build

The generated decoder and encoder .js and .wasm files are written to dist/.