GIF and Lossless PNG

imagemin-rs provides two GIF paths and two lossless PNG paths. Compatibility entry points retain familiar imagemin plugin names; explicit native entry points expose permissively licensed profiles that run in the napi-rs worker pool.

gifsicle(): compatibility sidecar

import imagemin, { gifsicle } from "imagemin-rs";

const output = await imagemin.buffer(input, {
  plugins: [gifsicle({ optimizationLevel: 3, colors: 128 })],
});

Supported options are interlaced, optimizationLevel: 1 | 2 | 3, and colors: 2..256. Omitting optimizationLevel adds no implicit level, matching the actual behavior of imagemin-gifsicle@7.0.0.

The adapter executes a separately built Gifsicle 1.96 sidecar rather than linking GPL code into the MIT native addon. Platform packages contain SHA-256 provenance and the GPL-2.0-only license. Application extensions are stripped by default, while loop and frame timing semantics are preserved. colors is a lossy quantization option.

giflossless(): conservative native optimization

import { giflossless } from "imagemin-rs";

const output = await giflossless({ strip: false })(input);

This profile uses a permissively licensed Rust parser and compositor. It re-encodes frames into a global palette and delta rectangles only when composited pixels can be proven equivalent. Animations that cannot be represented safely are returned unchanged. Metadata is retained by default; strip: true removes comment and application metadata but preserves looping.

Use gifsicle() when you need color quantization or Gifsicle optimization levels.

optipng(): OptiPNG-shaped native profile

import { optipng } from "imagemin-rs";

const output = await optipng({
  optimizationLevel: 3,
  bitDepthReduction: true,
  colorTypeReduction: true,
  paletteReduction: true,
  interlaced: false,
  errorRecovery: true,
})(input);

Defaults follow imagemin-optipng@8.0.0, including stripping ancillary metadata. The implementation uses oxipng@10.1.1, not OptiPNG 0.7.7, so it does not promise identical trial counts, repairs, or output bytes. Corpus tests verify decoded pixels across PNG color types and bit depths.

APNG is passed through. OptiPNG predates APNG, and stripping all metadata would remove animation chunks.

oxipng(): native Oxipng profile

oxipng() exposes Oxipng presets 0..6, strip: "none" | "safe" | "all", optimizeAlpha, and interlace. It accepts only a smaller or equal result. The two PNG factories are intentionally distinct: one maps the imagemin option shape, while the other expresses Oxipng policy directly.