mozjpeg-oxide

Pure Rust JPEG encoder based on Mozilla's mozjpeg, featuring trellis quantization for optimal compression.

Why mozjpeg-oxide?

	mozjpeg-oxide	C mozjpeg	libjpeg-turbo
Language	Pure Rust	C	C/asm
Memory safety	Compile-time guaranteed	Manual	Manual
Trellis quantization	Yes	Yes	No
File size	~Same as C	Baseline	5-15% larger
Build complexity	`cargo add`	cmake + nasm + C toolchain	cmake + nasm

Choose mozjpeg-oxide when you want:

Memory-safe JPEG encoding without C dependencies
Smaller files than libjpeg-turbo (trellis quantization)
Simple integration via Cargo

Choose C mozjpeg when you need:

Maximum baseline encoding speed (SIMD-optimized)
Established C ABI for FFI

Benchmark Results

Tested on Kodak + CLIC corpora (56 images total). Settings: progressive mode, trellis quantization, optimized Huffman, 4:2:0 subsampling.

Quality	Rust BPP	C BPP	Size Δ	Rust SSIM2	C SSIM2	Quality Δ
20	0.251	0.252	-0.3%	21.5	21.8	-0.30
50	0.534	0.532	+0.4%	57.3	57.5	-0.18
75	0.881	0.870	+1.3%	71.8	72.0	-0.13
85	1.251	1.224	+2.2%	77.8	77.9	-0.08
95	2.367	2.270	+4.3%	86.1	86.1	-0.03

Summary: Files are 0-4% larger than C mozjpeg with imperceptible quality difference (SSIM2 within 0.3 points).

Reproduce Benchmarks

# Fetch test corpus (Kodak images, ~15MB)
./scripts/fetch-corpus.sh

# Run benchmark
cargo bench-corpus

# Or just Kodak images
cargo bench-kodak

Results written to benchmark_results.csv. See also cargo bench-micro for criterion microbenchmarks.

Usage

use mozjpeg_oxide::{Encoder, Subsampling};

// Default: trellis quantization + Huffman optimization
let jpeg = Encoder::new()
    .quality(85)
    .encode_rgb(&pixels, width, height)?;

// Maximum compression: progressive + trellis + scan optimization
let jpeg = Encoder::max_compression()
    .quality(85)
    .encode_rgb(&pixels, width, height)?;

// Fastest: no optimizations (libjpeg-turbo compatible output)
let jpeg = Encoder::fastest()
    .quality(85)
    .encode_rgb(&pixels, width, height)?;

// Custom configuration
let jpeg = Encoder::new()
    .quality(75)
    .progressive(true)
    .subsampling(Subsampling::S420)
    .optimize_huffman(true)
    .encode_rgb(&pixels, width, height)?;

Features

Trellis quantization - Rate-distortion optimized coefficient selection
Progressive JPEG - Multi-scan encoding with spectral selection
Huffman optimization - 2-pass encoding for optimal entropy coding
Overshoot deringing - Reduces ringing artifacts at sharp edges
Chroma subsampling - 4:4:4, 4:2:2, 4:2:0 modes
Safe Rust - #![deny(unsafe_code)] with exceptions only for SIMD intrinsics

Performance

Configuration	vs C mozjpeg	Notes
Baseline (no opts)	~4x slower	C has SIMD entropy coding
Trellis enabled	0.9x (faster)	Trellis dominates runtime
Max compression	0.6x (faster)	Progressive + trellis

With trellis quantization enabled (the default), mozjpeg-oxide matches or exceeds C mozjpeg performance.

License

BSD-3-Clause - Same license as the original mozjpeg.

Acknowledgments

Based on Mozilla's mozjpeg, which builds on libjpeg-turbo and the Independent JPEG Group's libjpeg.

mozjpeg-oxide 0.1.0