-r Tells g32pbm to interpret bits least-significant first, instead of the default most-significant
first ("-reversebits"). Some fax modems do it one way and others do it the other way. If you get
a whole bunch of "invalid code" messages (nearly one per line), try using this flag.
-s Double each horizontal row of the fax file in the pbm file ("-stretch)". You can use this to
adjust the aspect ratio of a "normal resolution" fax file to match that of a "fine resolution" fax
file. This might not seem like it belongs here, but it's much faster than using pnmscale|pgmtopbm
later. -s is activated automatically if the file is specified on the command line and its name
starts with "fn..." (fax/normal).
-l(aserjet)
Instead of a portable bitmap (PBM), output HP laserjet files, suitable for direct printing on a HP
laserjet or desjket.
-d<dpi>
Scale output to <dpi> dots per inch before printing. Normal FAX resolution is 204x196 dpi (fine
mode), or 204x98 dpi (normal mode). In LaerJet mode, only the values 75, 150 and 300 are allowed
for <dpi>.
-t turn image by 90 degrees clockwise. Multiple -t commands increase angle, that is, -t -t will turn
it upside down, and so on.
-? Print a short command syntax.