macptopbm(1) General Commands Manual macptopbm(1)NAME
macptopbm - convert a MacPaint file into a portable bitmap
SYNOPSIS
macptopbm [-extraskip N] [macpfile]
DESCRIPTION
Reads a MacPaint file as input. Produces a portable bitmap as output.
OPTIONS -extraskip
This flag is to get around a problem with some methods of transferring files from the Mac world to the Unix world. Most of these
methods leave the Mac files alone, but a few of them add the "finderinfo" data onto the front of the Unix file. This means an extra
128 bytes to skip over when reading the file. The symptom to watch for is that the resulting PBM file looks shifted to one side.
If you get this, try -extraskip 128, and if that still doesn't look right try another value.
All flags can be abbreviated to their shortest unique prefix.
SEE ALSO picttoppm(1), pbmtomacp(1), pbm(5)AUTHOR
Copyright (C) 1988 by Jef Poskanzer. The MacPaint-reading code is copyright (c) 1987 by Patrick J. Naughton (naughton@wind.sun.com).
29 March 1989 macptopbm(1)
Check Out this Related Man Page
pbmreduce(1) General Commands Manual pbmreduce(1)NAME
pbmreduce - read a portable bitmap and reduce it N times
SYNOPSIS
pbmreduce [-floyd|-fs|-threshold ] [-value val] N [pbmfile]
DESCRIPTION
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 "re-halftone" an image. Let's say you have a scanner that only produces black&white, not grayscale, and it does a
terrible job of halftoning (most b&w scanners fit this description). One way to fix the halftoning is to scan at the highest possible res-
olution, say 300 dpi, and then reduce by a factor of three or so using pbmreduce. You can even correct the brightness of an image, by
using the -value flag.
OPTIONS
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.
SEE ALSO pnmenlarge(1), pnmscale(1), pgmtopbm(1), pbm(5)AUTHOR
Copyright (C) 1988 by Jef Poskanzer.
02 August 1989 pbmreduce(1)
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