ppmdist - simplistic grayscale assignment for machine generated, color images
Reads a portable pixmap as input, performs a simplistic
grayscale assignment intended for use with grayscale or
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
A ppm input of n colors is read, and a pgm of n gray levels
is written. The gray levels take on the values 0..n-1, while
maxval takes on n-1.
The mapping from color to stepped grayscale can be performed
in order of input pixel intensity, or input pixel frequency
(number of repetitions).
Sort input colors by the number of times a color appears in
the input, before mapping to evenly distributed graylevels
of output. -intensity Sort input colors by their
grayscale intensity, before mapping to evenly distributed
graylevels of output. This is the default.
Helpful only for images with a very small number of colors.
Perhaps should have been an option to
ppmtopgm(1), ppmhist(1), ppm(5)
Copyright (C) 1993 by Dan Stromberg.