- Produce a grayscale version of the specified PPM image:
ppmdist path/to/input.ppm > path/to/output.pgm
- Specify the method used to map colors to graylevels:
ppmdist -frequency|intensity path/to/input.ppm > path/to/output.pgm
This program is part of Netpbm(1).
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 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).
This program is helpful only for images with a very small number of colors.
In addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options ), ppmdist recognizes the following command line options:
Sort input colors by the number of times a color appears in the input, before mapping to evenly distributed graylevels of output.
Sort input colors by their grayscale intensity, before mapping to evenly distributed graylevels of output. This is the default.
ppmtopgm(1), ppmhist(1), ppm(1)
Copyright (C) 1993 by Dan Stromberg.
This manual page was generated by the Netpbm tool 'makeman' from HTML source. The master documentation is at