pbmreduce
NAME SYNOPSIS DESCRIPTION OPTIONS SEE ALSO AUTHOR
pbmreduce - read a portable bitmap and reduce it N times
pbmreduce [__-floyd__? [__-value__ ''val''? N [''pbmfile''?
Reads a portable bitmap as input. Reduces it by a factor of N, and produces a portable bitmap as output.
pbmreduce duplicates a lot of the functionality of pgmtopbm; you could do something like pnmscale | pgmtopbm, but pbmreduce is a lot faster.
pbmreduce can be used to pbmreduce. You can even correct the brightness of an image, by using the -value flag.
By default, the halftoning after the reduction is done via boustrophedonic Floyd-Steinberg error diffusion; however, the -threshold flag can be used to specify simple thresholding. This gives better results when reducing line drawings.
The -value flag alters the thresholding value for all quantizations. It should be a real number between 0 and 1. Above 0.5 means darker images; below 0.5 means lighter.
All flags can be abbreviated to their shortest unique prefix.
pnmenlarge(1), pnmscale(1), pgmtopbm(1), pbm(5)
Copyright (C) 1988 by Jef Poskanzer.
5 pages link to pbmreduce(1):
