Section: User Commands (1)
Updated: 08 April 2000
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pnmdepth - change the maxval in a portable anymap
Reads a portable anymap as input.
Scales all the pixel values, and writes out the image with the new maxval.
Scaling the colors down to a smaller maxval will result in some loss
Be careful of off-by-one errors when choosing the new maxval.
For instance, if you want the color values to be five bits wide,
use a maxval of 31, not 32.
One important use of
is to convert a new format 2-byte-per-sample PNM file to the older
1-byte-per-sample format. Before April 2000, essentially all raw
(binary) format PNM files had a maxval less than 256 and one byte per
sample, and many programs may rely on that. If you specify a
less than 256, the resulting file should be readable by any program
that worked with PNM files before April 2000.
pnm(5), ppmquant(1), ppmdither(1)
Copyright (C) 1989, 1991 by Jef Poskanzer.
- SEE ALSO
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using the manual pages.
Time: 16:19:42 GMT, January 22, 2018