This program is part of Netpbm(1).
fstopgm reads a Usenix FaceSaver(tm) file as input and produces a PGM image 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 pamscale 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 pamscale.
Then use one of the following pipelines:
fstopgm | pnmnorm fstopgm | pamscale -whatever | pnmnorm
To go to PBM, you want something more like one of these:
fstopgm | pamenlarge 3 | pnmnorm | pamditherbw fstopgm | pamenlarge 3 | pamscale <whatever> | pnmnorm | pamditherbw
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 Oakland, CA.
There are no command line options defined specifically
for fstopgm, but it recognizes the options common to all
programs based on libnetpbm (See
Common Options .)