openjpegjs

This library is a JavaScript port made possible by emscripten and Chris Hafey. It is a JavaScript and WebAssembly build of OpenJPEG.

Table of Contents

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Features

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Installing

Using npm:

$ npm install @cornerstonejs/openjpegjs

Using yarn:

$ yarn add @cornerstonejs/openjpegjs

Using unpkg CDN:

<script src="https://unpkg.com/@???/openjpegjs"></script>

Try It Out!

Try it in your browser here

openjpegjs API

Creating an instance

// JS / WASM promises resolve the library
const openjpegwasm = await OpenJPEGWASM;
const openjpegjs = await OpenJPEGJS;

// Decoder
const J2KDecoder = new openjpegjs.J2KDecoder();

// Encoder
const J2KEncoder = new openjpegjs.J2KEncoder();

Decoder instance methods

• J2KDecoder#getEncodedBuffer([encodedBitStreamLength: int]): ArrayBuffer
• J2KDecoder#getDecodedBuffer(): ArrayBuffer
• J2KDecoder#readHeader(): ?
• J2KDecoder#calculateSizeAtDecompositionLevel(decodeLevel: int): void
• J2KDecoder#decode(): void
• J2KDecoder#decodeSubResolution(decodeLevel: int, decodeLayer: int)
• J2KDecoder#getFrameInfo(): FrameInfo
• J2KDecoder#getNumDecomposition(): int
• J2KDecoder#getIsReversible(): bool
• J2KDecoder#getProgressionOrder(): int
• J2KDecoder#getImageOffset(): Point
• J2KDecoder#getTileSize(): Size
• J2KDecoder#getTileOffset(): Point
• J2KDecoder#getBlockDimensions(): Size
• J2KDecoder#getNumLayers(): int
• J2KDecoder#getColorSpace(): int

// ~ Setup
// const encodedArrayBuffer = ...;
const fullEncodedBitStream = new Uint8Array(encodedArrayBuffer);
const numBytes = 0;
const encodedBitStream = new Uint8Array(encodedArrayBuffer, 0, fullEncodedBitStream.length -numBytes);

// ~ DECODE
const encodedBuffer = decoder.getEncodedBuffer(encodedBitStream.length);
encodedBuffer.set(encodedBitStream);
decoder.decode(); // or .decodeSubResolution() to go by layer or level

// ~ Display (see example index.html file)
const decodedBuffer = decoder.getDecodedBuffer();
const frameInfo = decoder.getFrameInfo(); // width/height will be wrong if using decodeSubResolution
const interleaveMode = 2;

// In example index.html file
display(frameInfo, decodedBuffer, interleaveMode)

Encoder instance methods

• J2KEncoder#getDecodedBuffer
• J2KEncoder#getEncodedBuffer
• J2KEncoder#encode
• J2KEncoder#setDecompositions
• J2KEncoder#setQuality
• J2KEncoder#setProgressionOrder
• J2KEncoder#setDownSample
• J2KEncoder#setImageOffset
• J2KEncoder#setTileSize
• J2KEncoder#setTileOffset
• J2KEncoder#setBlockDimensions
• J2KEncoder#setNumPrecincts
• J2KEncoder#setPrecinct
• J2KEncoder#setCompressionRatio

Contributing

It can be difficult to contribute if your environment is not setup correctly. I highly recommend trying out VS Code's "Dev Containers" that make it easier to share and use a consistent development environment.

Dev Containers

• Setting up VS Code Dev Containers
• Additional Dev Containers configuration guidance

Requirements

0. VS Code and Docker Desktop
1. Remote-Containers extension
2. Command Pallete --> Remote-Containers: Open Folder in Container