oxipng_deflater_comparison.md

#	Test	Command	8.0.0	PATCH
1	zlib, o6	oxipng -o 6 -i 0 --out 01_oxi_normal.png t.png	48290731	45277379
2	same, interlaced	oxipng -o 6 -i 1 --out 02_oxi_normal_interlaced.png t.png	50144548	50144548
3	max zlib	oxipng --zc 12 -o max -i 0 -a --out 03_zc12_b.png t.png	48290731	45277379
4	Zopfli	oxipng -Z -o 6 -i 0 --out 03_oxi_normal_ZOPFLI.png t.png	47883283	47883283

Comparison of output file size for example images processed with oxipng. Comparing libdeflater 0.11.0 and 0.13.0

oxipng_test.sh

#!/bin/bash

wget -O t.png https://stsci-opo.org/STScI-01G8GYD8B1H306SSPR4MY6NGN0.png

# zlib
oxipng -o 6 -i 0 --out 01_oxi_normal.png t.png
oxipng -o 6 -i 1 --out 02_oxi_normal_interlaced.png t.png
oxipng --zc 12 -o max -i 0 -a --out 03_zc12_b.png t.png

# Zopfli
oxipng -Z -o 6 -i 0 --out 03_oxi_normal_ZOPFLI.png t.png
oxipng -Z -o max -i 0 --strip all --threads 8 --out

ls -la

• oxipng -o6 yields 48290731 (0.11.0) / 45277379 (0.13.0)
• oxipng --zc 12 -o max 48290731 (0.11.0) / 45277379 (0.13.0)

@parasew Do you happen to have timing info for those gist trials? It'd be instructive to know how much longer 1 zip library took over the other to produce exactly the same-size file, even w/ the 6- vs 8- thread difference.