pnmquant(1) on Linux
The text ca418cebda55, as Debian 12 (Bookworm) shipped it.
quantize the colors in a Netpbm image to a smaller set
Flags it lists
-
-center -
-floyd -
-fs -
-meancolor -
-meanpixel -
-nofloyd -
-nofs -
-norandom -
-randomseed -
-spreadbrightness -
-spreadluminosity