This program is part of Netpbm.
ppmdist reads a PPM image as input and performs a simplistic grayscale
assignment intended for use with grayscale or bitmap printers.
Often conversion from ppm to pgm will yield an image with contrast too
low for good printer output. The program maximizes contrast between
the gray levels output.
A ppm input of n colors is read, and a pgm of n gray levels is writ-
ten. The gray levels take on the values 0..n-1, while maxval takes on
The mapping from color to stepped grayscale can be performed in order
of input pixel intensity, or input pixel frequency (number of repeti-
This program is helpful only for images with a very small number of
ppmtopgm, ppmhist, ppm
Copyright (C) 1993 by Dan Stromberg.
netpbm documentation 22 July 1992 Ppmdist User Manual(0)