fax2tiff - create a TIFF Class F fax file from raw fax data
fax2tiff [ options ] [ -o output.tif ] input.g3
Fax2tiff creates a TIFF file containing CCITT Group 3 or Group 4 encoded data from one or
more files containing ``raw'' Group 3 encoded data (typically obtained directly from a fax
modem). By default, each row of data in the resultant TIFF file is 2-dimensionally
encoded and padded or truncated to 1728 pixels, as needed. The resultant image is a set
of low resolution (98 lines/inch) or medium resolution (196 lines/inch) pages, each of
which is a single strip of data. The generated file conforms to the TIFF Class F (FAX)
specification for storing facsimile data. This means, in particular, that each page of
the data does not include the trailing return to control (RTC) code; as required for
transmission by the CCITT Group 3 specifications. The old, ``classic'', format is created
if the -c option is used. (The Class F format can also be requested with the -f option.)
The default name of the output image is fax.tif; this can be changed with the -o option.
Each input file is assumed to be a separate page of facsimile data from the same document.
The order in which input files are specified on the command line is the order in which the
resultant pages appear in the output file.
Options that affect the interpretation of input data are:
-2 Assume input data is 2-d Huffman encoded.
-B Assume input data was encoded with black as 0 and white as 1.
-L Treat input data as having bits filled from least significant bit (LSB) to most
significant bit (MSB). (This is the default.)
-M Treat input data as having bits filled from most significant bit (MSB) to most
least bit (LSB).
-R Specify the vertical resolution, in lines/inch, of the input images. By default
input are assumed to have a vertical resolution of 196 lines/inch. If images are
low resolution facsimile, a value of 98 lines/inch should be specified.
-W Assume input data was encoded with black as 1 and white as 0. (This is the
Options that affect the output file format are:
-1 Force output to be compressed with the 1-dimensional version of the CCITT Group 3
Huffman encoding algorithm.
-4 Force output to be compressed with the CCITT Group 4 Huffman encoding.
-o Specify the name of the output file.
-p Force the last bit of each End Of Line (EOL) code to land on a byte boundary. This
``zero padding'' will be reflected in the contents of the Group3Options tag of the
resultant TIFF file.
-s Stretch the input image vertically by writing each input row of data twice to the
-v Force fax2tiff to print the number of rows of data it retrieved from the input
The following warnings and errors come from the decoding routines in the library.
Warning, %s: Premature EOL at scanline %d (x %d).\n. The input data had a row that was
shorter than the expected value of 1728. The row is padded with white.
%s: Premature EOF at scanline %d (x %d).\n. The decoder ran out of data in the middle of
a scanline. The resultant row is padded with white.
%s: Bad code word at row %d, x %d\n. An invalid Group 3 code was encountered while decod-
ing the input file. The row number and horizontal position is given. The remainder of
the input row is discarded, while the corresponding output row is padded with white.
%s: Bad 2D code word at scanline %d.\n. An invalid Group 4 or 2D Group 3 code was encoun-
tered while decoding the input file. The row number and horizontal position is given.
The remainder of the input row is discarded, while the corresponding output row is padded
Should not have the constant width 1728 built into it. Input data are assumed to have a a
``top left'' orientation; it should be possible to override this assumption from the com-
CCITT Recommendation T.4 (Standardization of Group 3 Facsimile Apparatus for Document
The Spirit of TIFF Class F, an appendix to the TIFF 5.0 specification prepared by Cygnet
tiffinfo(1), tiffdither(1), tiffgt(1), libtiff(3).
September 24, 1994 FAX2TIFF(1)