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Apply dithering to a greyscale image, i.e. turn it into a pattern of black and white pixels that look the same as the original greyscale. See also: pbmreduce. More information:

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

ppmditherbw {{path/to/image.pgm}} > {{path/to/file.pgm}}

  • Use the specified quantization method:

ppmditherbw -{{floyd|fs|atkinson|threshold|hilbert|...}} {{path/to/image.pgm}} > {{path/to/file.pgm}}

  • Use the atkinson quantization method and the specified seed for a pseudo-random number generator:

ppmditherbw -atkinson -randomseed {{1337}} {{path/to/image.pgm}} > {{path/to/file.pgm}}

  • Specify the thresholding value for quantization methods that perform some sort of thresholding:

ppmditherbw -{{fs|atkinson|thresholding}} -value {{0.3}} {{path/to/image.pgm}} > {{path/to/file.pgm}}