pnmquant

Quantize the colors in a PNM image into a smaller set. This command is a combination of pnmcolormap and pnmremap and accepts the union of their options, except -mapfile. See also: pnmquantall. More information: https://netpbm.sourceforge.net/doc/pnmquant.html.

• Generate an image using only n_colors or less colors as close as possible to the input image:

pnmquant n_colors path/to/input.pnm > path/to/output.pnm