JBGTOPBM(1)JBGTOPBM(1)NAMEjbgtopbm - JBIG1 to portable bitmap file converter
SYNOPSISjbgtopbm [ options ] [ input-file | - [ output-file ]]
DESCRIPTION
Reads in a JBIG1 bi-level image entity (BIE) from a file or standard
input, decompresses it, and outputs a portable bitmap (PBM) file.
JBIG1 is a highly effective lossless compression algorithm for bi-level
images (one bit per pixel), which is particularly suitable for scanned
document pages.
A JBIG1 encoded image can be stored in several resolutions in one or
several BIEs. All resolution layers except the lowest one are stored
efficiently as differences to the next lower resolution layer. Options
-x and -y can be used to stop the decompression at a specified maximal
output image size. With option -m the input file can consist of multi-
ple concatenated BIEs which contain different increasing resolution
layers of the same image.
If more than one bit per pixel is stored in the JBIG1 file, then a PGM
file will be produced.
OPTIONS
- A single hyphen instead of an input file name will cause
jbgtopbm to read the data from standard input instead
from a file.
-x number Decode only up to the largest resolution layer which is
still not more than number pixels wide. If no such reso-
lution layer exists, then use the smallest one available.
-y number Decode only up to the largest resolution layer which is
still not more than number pixels high. If no such reso-
lution layer exists, then use the smallest one available.
Options -x and -y can also be used together in which case
the largest layer that satisfies both limits will be
selected.
-m Process multiple concatenated BIEs. If there are bytes
left after the final SDE in the first BIE, then with this
option jbgtopbm will attempt to decode these as the start
of another BIE that may contain higher resolution data.
Normally, any remaining bytes will generate a warning
message.
-b Use binary values instead of Gray code words in order to
decode pixel values from multiple bitplanes. This option
has only an effect if the input has more than one bit-
plane and a PGM output file is produced. Note that the
decoder has to be used in the same mode as the encoder
and cannot determine from the BIE, whether Gray or binary
code words were used by the encoder.
-d Diagnose a single BIE. With this option, jbgtopbm will
print a summary of the header information found in the
input file, followed by a list of all PSCD and ESC marker
sequences encountered until the end of the file is
reached.
-p number If the input contains multiple bitplanes, then extract
only the specified single plane as a PBM file. The first
plane has number 0.
BUGS
Using standard input and standard output for binary data works only on
systems where there is no difference between binary and text streams
(e.g., Unix). On other systems (e.g., MS-DOS), using standard input or
standard output may cause control characters like CR or LF to be
inserted or deleted and this will damage the binary data.
STANDARDS
This program implements the JBIG1 image coding algorithm as specified
in ISO/IEC 11544:1993 and ITU-T T.82(1993).
AUTHOR
The jbgtopbm program is part of the JBIG-KIT package, which has been
developed by Markus Kuhn. The most recent version of this portable
JBIG1 library and tools set is available from
<http://www.cl.cam.ac.uk/~mgk25/jbigkit/>.
SEE ALSOpbm(5), pgm(5), pbmtojbg(1)
2003-06-04 JBGTOPBM(1)
