pamdepth (1) Linux Manual Page
pamdepth – change the maxval in a Netpbm image
Synopsis
pamdepth newmaxval [netpbmfile]Description
This program is part of Netpbm(1)pamdepth reads a Netpbm image 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.
This program works on multi-image streams.
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 pamdepth 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(1) , pam(1) , pnmquant(1) , ppmdither(1)ppmbrighten(1)
pamfunc(1)