Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

Unreleased

Ssimulacra2.compare/5 and compare!/5 — compute the SSIMULACRA2 score between two packed-binary images. Scores are on the native 0–100 scale.
Ssimulacra2.Reference — new/4, new!/4, compare/3, compare!/3 for reusing one prepared reference across many candidates (~2× faster per compare in a quality-search loop).
Input formats selectable via the :format option: :rgb888 (default), :rgb16, :linear_rgb, :gray8, :linear_gray.
Cooperative cancellation: Ssimulacra2.CancelRef.new/0 and Ssimulacra2.cancel/1. The metric runs on a dirty scheduler and polls the cancel ref at strip boundaries, freeing the CPU promptly. A cancel ref is single-use.
Wall-clock timeouts via the :timeout option, returning {:error, :timeout}.
Optional Vix integration (Ssimulacra2.Vix.compare/2), available when :vix is a dependency.
Precompiled NIFs via rustler_precompiled for aarch64/x86_64 macOS, gnu/musl Linux, and x86_64 Windows, across NIF versions 2.15–2.17, so the Rust toolchain is not required on covered targets.

fast-ssim2 is pinned to a git revision because the cooperative-cancellation API (*_with_stop) has not yet landed in a crates.io release. This will move to a versioned dependency once available.
Scores are "SSIMULACRA2 as computed by fast-ssim2" and have not been bit-exactly validated against the canonical Cloudinary/libjxl reference.