oximg

High-performance image compression in Rust: a library, a CLI, and a self-hostable HTTP server (PoC). JPEG, PNG, and WebP in and out; sources are format-sniffed by magic bytes and re-encoded in their own format.

Pipeline

source bytes (local file or HTTP origin)
  → format sniff → decode
      JPEG: mozjpeg streaming decode, DCT shrink-on-load (kept ≥ 1.7x target size)
      PNG:  png crate (palette/gray/16-bit normalized to RGB(A)8)
      WebP: libwebp
  → linear-light resize: sRGB u8 → linear u16 → Lanczos3 (SIMD) → sRGB u8
      (alpha is premultiplied before resampling, unpremultiplied after)
  → encode in the source format
      JPEG: jpegli, progressive (PRESET=fast / PRESET=small select mozjpeg profiles)
      PNG:  png crate | WebP: libwebp

Concurrent identical requests are coalesced and share one result. CPU concurrency is pinned to the core count with a semaphore; the HTTP layer (axum/tokio) only does queueing and IO.

Benchmarks

• BENCH.md — throughput, latency, and memory vs imgproxy and imagor, on macOS and Linux x86_64.
• bench/quality/QUALITY.md — output quality (SSIMULACRA2) at matched settings vs imgproxy and sharp.

Usage

cargo build --release
IMAGES_DIR=./images PORT=8081 QUALITY=80 ./target/release/oximg
curl "localhost:8081/resize/500/500/photo.jpg" -o out.jpg

Or with Docker:

docker build -t oximg .
docker run -p 8081:8081 -v $PWD/images:/images:ro oximg

Environment variables: PORT (8081), IMAGES_DIR (./images), OXIMG_SOURCE_BASE_URL (fetch sources from <base>/<file> over HTTP instead of the local filesystem; streaming decode overlaps the download), OXIMG_MAX_SOURCE_BYTES (64MiB), QUALITY (80), PRESET (jpegli default; fast = mozjpeg baseline profile, small = mozjpeg trellis+progressive), OXIMG_RESIZE=srgb (resize in sRGB space instead of linear light), OXIMG_DCT_MARGIN (1.7), OXIMG_PAR (resize threads, 1).

Not yet implemented (out of PoC scope)

• Cross-format output and content negotiation (AVIF / JXL / Accept-driven)
• EXIF orientation / ICC profile handling
• S3 sources, URL signing, caching
• Production-grade load testing

Status

Experimental PoC — APIs and the HTTP interface will change without notice. The oximg crates.io / @oximg npm packages are name reservations for now.

License

Apache-2.0.

The compiled binary statically links third-party code (jpegli/libjxl — BSD-3-Clause, Highway — Apache-2.0, mozjpeg/libjpeg-turbo — IJG). Their license texts and required notices are bundled in THIRD-PARTY-LICENSES.md, generated with cargo about. Dependency licensing is gated in CI by cargo deny (deny.toml).