# dmtrKovalenko/odiff

A very fast SIMD-first image comparison library (with nodejs API)

Repository: https://github.com/dmtrKovalenko/odiff
Canonical: https://ross.abutalabs.com/products/odiff
Language: Zig
License: MIT
License Family: permissive
Topics: visual, diff, snapshot, image-comparison, testing-tool, pixel-perfect, odiff, hacktoberfest
Last push: 2026-08-24T16:04:17+00:00

## Health v2 (maintenance only)
Score: 97/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 94, longevity 100
- inputs: {"age_days": 2128, "days_push": 9, "days_rel": 42, "gap_med": 0, "n_releases_24m": 22}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3173, forks 115 (observed 2026-08-28T04:07:47.499619+00:00)

## What it is
ODiff is a very fast pixel-by-pixel image comparison library and CLI tool written in Zig with SIMD optimizations (SSE2, AVX2, AVX512, NEON). It supports cross-format comparison of PNG, JPEG, WebP, and TIFF images with features like anti-aliasing detection and region ignoring, plus a Node.js API.

## Use cases
- compare two images pixel by pixel
- visual regression testing for screenshots
- generate diff images between snapshots
- compare jpg and png images
- detect visual differences in UI screenshots
- snapshot testing for web apps
- fast image diffing in CI

## When to choose
- you need millisecond image comparisons in a test suite or CI pipeline
- you need cross-format comparison (e.g. jpg vs png) or anti-aliasing-aware diffs
- you want a native tool with a Node.js API and low memory footprint

## When to avoid
- you need perceptual hashing or image similarity search rather than strict pixel comparison
- you need a pure-JS solution without native binaries
- you work with formats outside png/jpeg/webp/tiff

## Facets
- artifact type: library
- maturity: active
- function: image-processing, testing, cli
- domain: image-processing, testing, developer-tools
- platform: cross-platform, cli
- tags: visual-regression, snapshot-testing, pixel-diff, simd, zig, visual-testing, nodejs

## Member repositories
- dmtrKovalenko/odiff (main) score 97

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:47.499619+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:45:27.169282+00:00, confidence not recorded.
  - readme: https://github.com/dmtrKovalenko/odiff (fetched 2026-08-28T04:07:47.499619+00:00, sha 6ec4ff9a93de)
- Data as of 2026-08-30T08:39:29.467469+00:00.