ppmdither

Reduce the number of colors in an image by applying dithering. More information: https://netpbm.sourceforge.net/doc/ppmdither.html.

• Read a PPM image, apply dithering and save it to a file:

ppmdither {{path/to/image.ppm}} > {{path/to/file.ppm}}

• Specify the desired number of shades for each primary color:

ppmdither {{[-r|-red]}} {{2}} {{[-g|-green]}} {{3}} {{[-b|-blue]}} {{2}} {{path/to/image.ppm}} > {{path/to/file.ppm}}

• Specify the dimensions of the dithering matrix:

ppmdither {{[-d|-dim]}} {{2}} {{path/to/image.ppm}} > {{path/to/file.ppm}}