cédric (dev) said on 07/26/2018

i finally implemented an old not-so-good idea * in 0.97.8 (edit: can be done with -pngrgb in 0.98.37). it does color quantization (it reduces the amount of colors), but in a very different way — this could require optimization atm

color quantization
command speed quality savings
-pngcolor fast good average
-pngrgb slow average good

that is basically what you could notice most of time but not always — imo it could offer better results than the old implementation of -pngcolor

original file: tweet.png (71 850 bytes)
pngcolor=80 pngfilter=1 pngrgb=100
40 953 bytes 30 618 bytes 27 940 bytes
0.00010051 0.00104274 0.00039614
1.093992 2.454066 2.183210
0.10s 0.08s 0.22s

* before using this, i suggest you try -pngfilter or -pngpalette first. you could get better quality/size ratio but i did not compare this seriously

comment this