Note that it's required to specify the number of colors (<ncolors>) or the mapfile. Arguments in square brackets are optional.
This manual page documents briefly the
pngquant quantizes one or more 32-bit RGBA PNGs to 8-bit (or smaller) RGBA-palette PNGs using either ordered dithering or Floyd-Steinberg diffusion dithering (default). The output filename is the same as the input name except that it ends in -fs8.png or -or8.png (unless the input is stdin, in which case the quantized image will go to stdout). The default behavior if the output file exists is to skip the conversion; use -force to overwrite.
Overwrite existing output files.
-ordened, -nofloyd, -nofs
Use ordered dithering.
Print status messages.
the -map option is NOT YET SUPPORTED.
Creating a new image with the number of colors reduced to 64:
pngquant 64 image.png
The resulting image will have 64 colors and will be saved as image-fs8.png.