g3topbm (1) - Linux Manuals

g3topbm: convert a Group 3 fax file into a portable bitmap

Command to display g3topbm manual in Linux: $ man 1 g3topbm

g3topbm - convert a Group 3 fax file into a portable bitmap

g3topbm [-kludge] [-reversebits] [-stretch] [g3file]

Reads a Group 3 fax file as input. Produces a portable bitmap as output.

-kludge: Tells g3topbm to ignore the first few lines of the file; sometimes fax files have some junk at the beginning.
-reversebits: Tells g3topbm to interpret bits least-significant first, instead of the default most-significant first. Apparently some fax modems do it one way and others do it the other way. If you get a whole bunch of "bad code word" messages, try using this flag.
-stretch: Tells g3topbm to stretch the image vertically by duplicating each row. This is for the low-quality transmission mode.

All flags can be abbreviated to their shortest unique prefix.

The standard for Group 3 fax is defined in CCITT Recommendation T.4.

Probably.