image optimizer for web

changelog

1.28.8 — 05/08/2026
improved APNG lossy/lossless
fixed crash during palettization for large images
improved auto for palettization (dithering)
improved savings -s0 lossless (not updated in benchmark)
improved speed/savings for most of profiles
improved savings & speed on most of lossless palette (PNG) — new filter
improved performance & savings of RGBA — new filter
changed resizer, no more lib: faster, lighter & simple
fixed old bug random effectiveness

1.28 — 21/07/2026 | see notes
improvements of many functions
fixed -s1 compression regression
fixed WebP to PNG conversion crash
fixed WebP RGBA to palette missed optimization
fixed compression regression

1.27 — 18/06/2026 | see notes
improved speed & reduced memory usage from -s1 to -s4 palette sorting (PNG)
fixed compression regression
improved palette sorting (PNG/WebP)
improved deflate speed/size further
improved WebP optimizer

1.26 — 15/06/2026 | see notes
improvements for palette sorting (PNG/WebP)
improved lossy palette conversion from noised image
unicode support + filename starting with -
		
1.25 — 08/09/2025 | see notes
optimization of implementations
fixed compression regressions
improved PNG filtering
	
1.24 — 22/07/2025
fixed heuristic for transforms
fixed palette sorting issue
improved text/noise transform
improved PNG and WebP lossless further (palette)
improved alpha-p palette optimization
fixed -s1 for mt
fixed JPEG quality heuristic for transforms
fixed near-gray

1.23 — 21/04/2024
improved palette lossless further (PNG/WebP)

1.22 — 18/04/2024
fixed & improved palette lossless (PNG)

1.21 — 15/04/2024
added lossy & keep alpha
fixed WebP lossy does not keep alpha with -noalpha
changed % considering processable files only
improved various code performance

1.20 — 20/03/2024
improved grayscale+alpha lossless filtering
changed behavior of -near=N on flat
improved lossy on near-grayscale images
fixed critical-typo on gray+alpha in fast lossless
fixed & improved fast lossless
fixed compression regression
fixed crash

1.19 — 07/03/2024
small improvements for palette sorting (PNG/WebP)
fixed & improved near-lossless (PNG/WebP)

1.18 — 27/02/2024
improved heuristic in auto (PNG/JPEG)
improved -grayscale performance
fixed -near=N behavior
various code optimization

1.17 — 13/01/2024
changed grayscale formula + fixes

1.16 — 15/11/2023
fixed and improved auto with palette as input (PNG/WebP)

1.15 — 30/10/2023
fixed palette stuff 3 (PNG)

1.14 — 26/10/2023
fixed palette stuff 2 (PNG)

1.13 — 25/10/2023
fixed palette stuff (PNG)

1.12 — 22/09/2023
added near stuff -near=N (PNG/JPEG/WebP)
improved lossless content-heuristic (PNG)

1.11 — 23/08/2023
improved -s0 lossless for paletted (PNG)			

1.10 — 22/08/2023
fixed handling of invalid APNG structure
improved conversion when using -grayscale and auto (APNG/PNG)
improved auto decisions (APNG/PNG/WebP)

1.09 — 01/08/2023
fixed incorrect optimization (APNG)

1.08 — 25/07/2023
fixed filter in auto (WebP)

1.07 — 25/07/2023
fixed grayscale and lossy (JPEG/WebP)

1.06 — 08/07/2023
improved heuristics for truecolor even more (WebP)

1.05 — 07/07/2023
fixed rotation and lossy (JPEG/WebP)
fixed some heuristics & improvements for truecolor stuff (WebP)
improved default efficiency for lossless WebP -s0

1.04 — 06/07/2023
improved auto decisions (PNG/WebP)

1.03 — 23/06/2023
improved auto decisions (PNG/WebP)

1.02 — 19/06/2023
fixed copy metadata

1.01 — 19/06/2023
fixed metadata handler -nostrip

1.00 — 14/06/2023 | see notes
initial 1.x release