oxcms - Oxidized Color Management System

A fast, safe, and complete color management system in Rust.

Goals

Combine the best of all CMS implementations:

Source	Contribution
moxcms	Rust safety, SIMD performance, modern API
lcms2	Full ICC v4.4, CMYK, DeviceLink, CIECAM02
skcms	OSS-Fuzz hardening, HDR (PQ/HLG)
qcms	Firefox battle-tested reliability

Status

Phase	Status	Description
Phase 1: Test Infrastructure	Complete	Parity tests, CI, documentation
Phase 2: Core Implementation	In Progress	See "Relationship with moxcms" below
Phase 3: Feature Parity	Planned	CMYK, DeviceLink, advanced features
Phase 4: Beyond lcms2	Planned	HDR, fuzzing, profile creation

Relationship with moxcms

oxcms currently wraps moxcms, an excellent Rust CMS by @awxkee. We're actively contributing bug fixes upstream:

• PR #139 - ARM64 NEON register fix
• PR #140 - V2 ICC white point handling
• PR #141 - Flexible version parsing

The long-term approach is undecided. We're evaluating:

1. Continue wrapping - Maintain oxcms as a stable API layer over moxcms
2. Deeper collaboration - Contribute features directly to moxcms
3. Independent implementation - Build from scratch if our requirements diverge

We prefer options 1 or 2. The goal is to improve the Rust color management ecosystem, not fragment it.

Phase 1 Achievements

• Workspace with oxcms-core, cms-tests, skcms-sys
• 185 parity tests (all passing)
• Cross-CMS comparison (moxcms, lcms2, qcms, skcms)
• DeltaE2000 accuracy measurement
• CI on Ubuntu, Windows, macOS (x86_64 + ARM64)
• ARM64 NEON bug identified and fixed in moxcms fork
• Math differences documented

Current Implementation

oxcms-core provides a stable API layer:

• Clean public types that don't leak moxcms internals
• All transforms currently delegated to moxcms
• Additional validation and error handling

Quick Start

# Run all tests
cargo test --all

# Run parity tests with output
cargo test -p cms-tests -- --nocapture

# Run specific test category
cargo test -p cms-tests lcms2_parity -- --nocapture
cargo test -p cms-tests math_differences -- --nocapture

Example Usage

use oxcms_core::{ColorProfile, Layout, TransformOptions};

// Create profiles
let srgb = ColorProfile::new_srgb();
let p3 = ColorProfile::new_display_p3();

// Create transform
let transform = srgb.create_transform_8bit(
    Layout::Rgb,
    &p3,
    Layout::Rgb,
    TransformOptions::default(),
).unwrap();

// Transform pixels
let src = [255u8, 128, 64];
let mut dst = [0u8; 3];
transform.transform(&src, &mut dst).unwrap();

Project Structure

oxcms/
├── crates/
│   ├── oxcms-core/     # Main CMS implementation (wraps moxcms)
│   ├── cms-tests/      # Cross-CMS parity tests
│   └── skcms-sys/      # FFI bindings to skcms
├── external/
│   └── moxcms/         # Forked moxcms with ARM64 fix
├── testdata/
│   └── corpus/         # 121 ICC test profiles
├── docs/               # Architecture, math differences
├── plans/              # Roadmap, implementation plan
└── tracking/           # Test status

Documentation

• Architecture - Design and structure
• Roadmap - Implementation phases
• Implementation Plan - Detailed approach
• Math Differences - CMS comparison results
• Test Status - Current test coverage

Test Results

All CMS implementations produce identical output for sRGB transforms:

Comparison	Max ΔE	Status
moxcms vs lcms2	0.0000	IDENTICAL
moxcms vs qcms	0.0000	IDENTICAL
qcms vs lcms2	0.0000	IDENTICAL

Performance Targets

Operation	Target	Reference
sRGB→sRGB 1MP	< 1ms	moxcms baseline
sRGB→P3 1MP	< 2ms	moxcms baseline
ICC parse	< 100μs	moxcms baseline

Goal: Match or exceed moxcms performance (3x+ faster than lcms2).

CMS Libraries Compared

Library	Language	Status
moxcms	Rust	Primary reference, forked with fixes
lcms2	C	Accuracy reference
skcms	C++	Security model reference
qcms	Rust	Firefox's CMS

AI-Generated Code Notice

This project was developed with assistance from Claude (Anthropic). While the code has been tested against multiple reference implementations and passes 185+ tests including cross-CMS parity validation, not all code has been manually reviewed.

Before using in production:

• Review critical code paths for your use case
• Run your own validation against expected outputs
• Consider the test suite coverage for your specific requirements

License

MIT OR Apache-2.0

Sources & Acknowledgments

• moxcms by @awxkee - Fast Rust CMS we build upon
• LittleCMS - Industry standard reference
• skcms - Chrome's CMS
• qcms - Firefox's CMS