Minimum unique abbreviation of option is acceptable. You may use double hyphens instead of single hyphen to denote options. You may use white space in place of the equals sign to separate an option name from its value.
This program is part of Netpbm.
g3topbm reads a Group 3 fax file as input and produces a PBM image as output.
If you don't specify this option, g3topbm does its best to work around input errors and salvage as much of the image as possible in the output image. It first tries to resynchronize to a later line by searching for the next End Of Line marker, skipping any lines or partial lines in between. It saves the beginning of the line in which it encountered the problem. If the input file ends prematurely, g3topbm produces output containing the lines up to where it encountered the problem.
g3topbm issues warning messages when it continues in spite of input errors.
This option was new in Netpbm 10.24 (August 2004). Before that, g3topbm always failed when it encountered premature EOF and never failed when it encountered other problems.
G3 is the near universal format used by fax machines. There is also a newer, more capable G4.
The standard for Group 3 fax is defined in CCITT Recommendation T.4. In the U.S., that is implemented by EIA standards EIA-465 and EIA-466. These standards cover the layers below the image format (which are irrelevant to g3topbm as well.
G3 faxes are 204 dots per inch (dpi) horizontally and 98 dpi (196 dpi optionally, in fine-detail mode) vertically. Since G3 neither assumes error free transmission nor retransmits when errors occur, the encoding scheme used is differential only over small segments never exceeding 2 lines at standard resolution or 4 lines for fine-detail. (The incremental G3 encoding scheme is called two-dimensional and the number of lines so encoded is specified by a parameter called k.)
Copyright (C) 1989 by Paul Haeberli <paul@manray.sgi.com>.