ppmdist - simplistic grayscale assignment for machine gen
erated, color images
SYNOPSIS
ppmdist [-intensity|-frequency] [ppmfile]
DESCRIPTION
Reads a portable pixmap as input, 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 lev
els 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 per
formed in order of input pixel intensity, or input pixel
frequency (number of repetitions).
OPTIONS
-frequency 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.
BUGS
Helpful only for images with a very small number of col
ors. Perhaps should have been an option to ppmtopgm(1).
SEE ALSO
ppmtopgm(1), ppmhist(1), ppm(5)
AUTHOR
Copyright (C) 1993 by Dan Stromberg.
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