pbmtopgm
convert portable bitmap to portable graymap by averaging areas
see also :
pgmtopbm
Synopsis
pbmtopgm
width height [pbmfile]
add an example, a script, a trick and tips
examples
no example yet ...
... Feel free to add your own example above to help other Linux-lovers !
description
pbmtopgm
reads a portable bitmap as input. It outputs a portable
graymap in which each pixel’s gray level is the
average the surrounding black and white input pixels. The
surrounding area is a rectangle of width by
height pixels.
In other words,
this is a convolution. pbmtopgm is similar to a
special case of pnmconvol.
You may need a
ppmsmooth step after pbmtopgm.
pbmtopgm
has the effect of anti-aliasing bitmaps which contain
distinct line features.
pbmtopgm
works best with odd sample width and heights.
You don’t
need pbmtopgm just to use a PGM program on a PBM
image. Any PGM program (assuming it uses the Netpbm
libraries to read the PGM input) takes PBM input as if it
were PGM, with only the mininum and maximum gray levels. So
unless your convolution rectangle is bigger than one pixel,
you’re not gaining anything with a pbmtopgm
step.
see also
netpbm,
pgmtopbm , pbm
author
Copyright (C)
1990 by Angus Duggan Copyright (C) 1989 by Jef
Poskanzer.
Permission to
use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in
all copies and that both that copyright notice and this
permission notice appear in supporting documentation. This
software is provided "as is" without express or
implied warranty.