CoreJ2K 2.1.0.101

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A Managed and Portable JPEG2000 Codec for .NET Platforms

🚀 Quick Start

dotnet add package CoreJ2K
dotnet add package CoreJ2K.Skia

Simple API

using CoreJ2K;
using CoreJ2K.Configuration;

// Decode
var image = J2kImage.FromStream(File.OpenRead("image.jp2"));
var bitmap = image.As<SKBitmap>();

// Encode with modern API (recommended)
byte[] data = CompleteConfigurationPresets.Web
    .WithCopyright("© 2025")
    .Encode(imageSource);

// Or use traditional API
byte[] j2kData = J2kImage.ToBytes(bitmap);

📖 Full Documentation • 💻 More Examples • 🎯 Modern API Guide • 📦 All Packages

📑 Table of Contents

• About
  • What is CoreJ2K?
  • Key Features
  • Why Choose CoreJ2K?
• Getting Started
  • Installation
  • Quick Examples
  • Platform Support
• Documentation
  • Encoding Guide
  • Advanced Parameters
  • Usage Notes
• Standards & Compliance
  • JPEG 2000 Part 1 (100%)
  • Library Comparison
  • Full Specification Details
• Support
• Contributing
• **License

About

What is CoreJ2K?

CoreJ2K is a pure C# implementation of the JPEG 2000 image compression standard for .NET. Modern fork of CSJ2K (C# port of jj2000), designed for .NET Standard and modern .NET platforms. Provides both encoding and decoding with 100% ISO/IEC 15444-1 Part 1 compliance.

Key Features

Why Choose CoreJ2K?

Comparison: CoreJ2K is the only open-source .NET library with full JPEG 2000 Part 1 compliance and complete pointer marker read/write support.

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Getting Started

Installation

Core Library

dotnet add package CoreJ2K

With Image Integration

# SkiaSharp (recommended - cross-platform)
dotnet add package CoreJ2K.Skia

# ImageSharp (modern .NET)
dotnet add package CoreJ2K.ImageSharp

# System.Drawing (Windows)
dotnet add package CoreJ2K.Windows

# Pfim (DDS/TGA)
dotnet add package CoreJ2K.Pfim

Quick Examples

Basic Decoding

using CoreJ2K;
using SkiaSharp;

// From file
var image = J2kImage.FromStream(File.OpenRead("image.jp2"));
var bitmap = image.As<SKBitmap>();

// From bytes
byte[] data = File.ReadAllBytes("image.j2k");
var image2 = J2kImage.FromBytes(data);

// Save as PNG
using var output = File.OpenWrite("output.png");
bitmap.Encode(output, SKEncodedImageFormat.Png, 90);

Basic Encoding

// Default (high quality)
byte[] j2k = J2kImage.ToBytes(bitmap);

// Lossless
var lossless = new ParameterList { ["lossless"] = "on", ["file_format"] = "on" };
byte[] data = J2kImage.ToBytes(bitmap, lossless);

// Lossy with target bitrate
var lossy = new ParameterList { ["rate"] = "0.5", ["file_format"] = "on" };
byte[] compressed = J2kImage.ToBytes(bitmap, lossy);

Platform Support

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Documentation

Modern Configuration API

CoreJ2K 1.3.0+ includes a comprehensive, fluent configuration API that makes JPEG 2000 encoding easier and more intuitive than ever.

Quick Start with Presets

using CoreJ2K.Configuration;

// One-liner encoding with preset
byte[] webImage = CompleteConfigurationPresets.Web
    .WithCopyright("© 2025")
    .Encode(imageSource);

// Medical imaging (lossless)
byte[] medical = CompleteConfigurationPresets.Medical
    .WithMetadata(m => m
        .WithComment("Patient: Anonymous")
        .WithComment("Study: CT Scan"))
    .Encode(dicomImage);

// High-quality photography
byte[] photo = CompleteConfigurationPresets.Photography
    .WithCopyright("© 2025 Photographer")
    .WithComment("Sunset over mountains")
    .Encode(photograph);

Quality Presets

// Lossless (perfect reconstruction)
var config = new CompleteEncoderConfigurationBuilder()
    .ForLossless()
    .Build();

// High quality (90% quality)
var config = new CompleteEncoderConfigurationBuilder()
    .ForHighQuality()
    .Build();

// Balanced (75% quality)
var config = new CompleteEncoderConfigurationBuilder()
    .ForBalanced()
    .Build();

// High compression
var config = new CompleteEncoderConfigurationBuilder()
    .ForHighCompression()
    .Build();

Use Case Presets

// Medical imaging - lossless with appropriate settings
.ForMedical()

// Archival storage - very high quality + error resilience
.ForArchival()

// Web delivery - progressive + balanced quality
.ForWeb()

// Thumbnail generation - fast + small
.ForThumbnail()

// Geospatial/GIS - spatial browsing + tiled
.ForGeospatial()

// Streaming - quality progressive
.ForStreaming()

Fine-Grained Control

var config = new CompleteEncoderConfigurationBuilder()
    .WithQuality(0.85)
    .WithQuantization(q => q
        .UseExpounded()
        .WithBaseStepSize(0.008f)
        .WithGuardBits(2))
    .WithWavelet(w => w
        .UseIrreversible_9_7()
        .WithDecompositionLevels(6))
    .WithProgression(p => p.UseLRCP())
    .WithTiles(t => t.SetSize(512, 512))
    .WithMetadata(m => m
        .WithComment("Custom configuration")
        .WithCopyright("© 2025")
        .WithXml(customMetadata))
    .Build();

byte[] data = J2kImage.ToBytes(image, config);

📚 Complete Guides:

• Complete Builder Guide - Unified API with presets
• Encoder Configuration Guide - Encoding parameters
• Quantization Configuration Guide - Quality/size trade-offs
• Wavelet Configuration Guide - Transform settings
• Progression Configuration Guide - Data organization
• Metadata Configuration Guide - Comments, copyright, XML

Traditional API (Encoding Guide)

Lossless

var p = new ParameterList();
p["lossless"] = "on";
p["file_format"] = "on";
byte[] data = J2kImage.ToBytes(bitmap, p);

Lossy with Quality

var p = new ParameterList();
p["rate"] = "0.5";         // 0.5 bits/pixel
p["file_format"] = "on";   // JP2 wrapper
p["tiles"] = "1024 1024";  // Tile size
p["Wlev"] = "5";           // Decomposition levels
byte[] data = J2kImage.ToBytes(bitmap, p);

Progressive Quality Layers

var p = new ParameterList();
p["rate"] = "0.2";
p["Alayers"] = "0.015 +20 2.0 +10";  // Multiple layers
p["Aptype"] = "res";                  // Resolution progression
byte[] data = J2kImage.ToBytes(bitmap, p);

Advanced Parameters

Common encoder parameters (case-sensitive):

Note: Parameter names match internal encoder conventions (no leading dashes).

Usage Notes

• InterleavedImage: Cross-platform image wrapper. Use As<T>() to convert to platform types (e.g., SKBitmap)
• ParameterList: Optional encoding parameters. Use indexer to set: params["key"] = "value"
• Image Sources: Accepts SKBitmap, Bitmap, Image, or codec-specific formats (PGM/PPM/PGX streams)
• Thread Safety: Decoding and encoding operations are thread-safe

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Standards & Compliance

Part 1: Core Coding System

CoreJ2K achieves 100% JPEG 2000 Part 1 (ISO/IEC 15444-1) compliance:

Compliance Scores:

• Baseline Profile: ✅ 100%
• Profile 0: ✅ 100%
• Profile 1: ✅ 100%
• Extended Features: ✅ 100%

Library Comparison

Quick comparison with major JPEG 2000 libraries:

CoreJ2K Unique Advantages:

• Only open-source .NET library with full Part 1 compliance
• Only open-source library with complete pointer marker read/write
• Memory-safe managed code (no buffer overflows)
• Zero licensing costs

📊 View detailed comparison tables →

JPEG 2000 Specification Compliance

CoreJ2K supports multiple parts of ISO/IEC 15444:

Part 1 covers 99% of real-world JPEG 2000 usage including:

• ✅ Medical imaging (DICOM)
• ✅ Digital cinema (DCP)
• ✅ Geospatial/satellite imagery
• ✅ Digital archives and libraries
• ✅ High-quality image storage

📖 View complete specification details →

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Support

Resources

• 📚 Documentation: This README and inline code docs
• 💬 Discussions: GitHub Discussions
• 🐛 Bug Reports: GitHub Issues
• 📦 Packages: NuGet Gallery

External Links

• JPEG 2000 Implementation Guide
• ISO/IEC 15444-1 Standard
• SkiaSharp GitHub
• ImageSharp GitHub
• OpenJPEG GitHub

Support the Project

If CoreJ2K helps your project:

• ⭐ Star the repository on GitHub
• 📢 Share with others
• 💰 Donate via cryptocurrency:
  • 
  • 

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Contributing

Contributions welcome! Ways to help:

• 🐛 Report bugs via GitHub Issues
• 💡 Suggest features in Discussions
• 📝 Improve docs with pull requests
• 🧪 Add tests for better coverage
• 🔧 Fix issues and submit PRs

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License

BSD 3-Clause License

Copyright (c) 1999-2000 JJ2000 Partners
Copyright (c) 2007-2012 Jason S. Clary
Copyright (c) 2013-2016 Anders Gustafsson, Cureos AB
Copyright (c) 2024-2025 Sjofn LLC

Free to use in commercial and open-source projects. No licensing fees.

→ Full license text

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Made with ❤️ for the .NET community

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Appendix: Detailed Comparison Tables

<details> <summary><b>Click to expand full library comparison</b></summary>

Standards Compliance and Features

Technical Characteristics

Performance and Quality

Developer Experience

Use Case Suitability