fstopgm - convert a Usenix FaceSaver(tm) file into a portable graymap
Reads a Usenix FaceSaver(tm) file as input. Produces a portable
graymap as output.
FaceSaver(tm) files sometimes have rectangular pixels. While fstopgm
won’t re-scale them into square pixels for you, it will give you the
precise pnmscale command that will do the job. Because of this,
reading a FaceSaver(tm) image is a two-step process. First you do:
fstopgm > /dev/null
This will tell you whether you need to use pnmscale. Then use one of
the following pipelines:
fstopgm | pgmnorm
fstopgm | pnmscale -whatever | pgmnorm
To go to PBM, you want something more like one of these:
fstopgm | pnmenlarge 3 | pgmnorm | pgmtopbm
fstopgm | pnmenlarge 3 | pnmscale <whatever> | pgmnorm | pgmtopbm
You want to enlarge when going to a bitmap because otherwise you lose
information; but enlarging by more than 3 does not look good.
FaceSaver is a registered trademark of Metron Computerware Ltd. of
pgmtofs(1), pgm(5), pgmnorm(1), pnmenlarge(1), pnmscale(1), pgmtopbm(1)
Copyright (C) 1989 by Jef Poskanzer.
06 April 89 fstopgm(1)