jpegli-rs

Pure Rust implementation of jpegli - Google's improved JPEG encoder/decoder from the JPEG XL project.

Features

Pure Rust - No C/C++ dependencies required
Perceptual optimization - Uses adaptive quantization for better visual quality
Backward compatible - Produces standard JPEG files readable by any decoder
SIMD accelerated - Uses wide crate for portable SIMD
Color management - Optional ICC profile support via lcms2

What is jpegli?

jpegli is Google's improved JPEG encoder that produces smaller files at the same visual quality, or better quality at the same file size. It achieves this through:

Adaptive quantization - Content-aware bit allocation
Improved quantization tables - Better than standard IJG libjpeg tables
XYB color space (optional) - Perceptually optimized color representation
Smart zero-biasing - Intelligent coefficient rounding

Usage

use jpegli_rs::{Encoder, Quality, PixelFormat};

// Encode RGB image data to JPEG
let jpeg_data = Encoder::new()
    .width(800)
    .height(600)
    .pixel_format(PixelFormat::Rgb)
    .quality(Quality::default())  // Q90
    .encode(&rgb_pixels)?;

// Write to file
std::fs::write("output.jpg", &jpeg_data)?;

Feature Flags

simd (default) - Enable SIMD acceleration
cms (default) - Enable color management (uses lcms2)
cms-lcms2 - Use lcms2 for color management
cms-moxcms - Use moxcms for color management (pure Rust)

Performance

jpegli-rs achieves 10-17% better quality (measured by DSSIM) at the same file size compared to mozjpeg, or produces 5-8% smaller files at equivalent quality.

Development

Running FFI Comparison Tests

To verify the Rust implementation matches the C++ original:

# Linux/macOS
./internal/setup-ffi-tests.sh

# Windows
.\internal\setup-ffi-tests.ps1

This requires CMake, a C++ compiler, and ~10 minutes for the initial C++ build. See internal/README.md for details.

Acknowledgments

This is a Rust port of jpegli from the JPEG XL project by Google.

License

AGPL-3.0-or-later. A commercial license is available from https://imageresizing.net/pricing

The original jpegli from libjxl is BSD-3-Clause licensed. See LICENSE for full details.

AI-Generated Code Notice

This crate was developed with significant assistance from Claude (Anthropic). While extensively tested against the C++ reference implementation with 100+ parity tests, not all code paths have been manually reviewed.

Before production use in critical applications:

Review code paths relevant to your use case
Run your own validation tests
Report any issues at https://github.com/imazen/jpegli-rs/issues

jpegli-rs 0.2.1