pnmdepth
Section: User Commands (1)
Updated: 08 April 2000
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NAME
pnmdepth - change the maxval in a portable anymap
SYNOPSIS
pnmdepth
newmaxval
[pnmfile]
DESCRIPTION
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
of information.
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
pnmdepth
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
newmaxval
less than 256, the resulting file should be readable by any program
that worked with PNM files before April 2000.
SEE ALSO
pnm(5), ppmquant(1), ppmdither(1)
AUTHOR
Copyright (C) 1989, 1991 by Jef Poskanzer.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
- AUTHOR
-
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