114 lines
3.4 KiB
Groff
114 lines
3.4 KiB
Groff
.TH JBGTOPBM 1 "2014-08-22"
|
|
.SH NAME
|
|
jbgtopbm \- JBIG1 to portable bitmap file converter
|
|
.SH SYNOPSIS
|
|
.B jbgtopbm
|
|
[
|
|
.I options
|
|
]
|
|
[
|
|
.I input-file
|
|
| \- [
|
|
.I output-file
|
|
]]
|
|
.br
|
|
.SH DESCRIPTION
|
|
Reads in a
|
|
.I JBIG1
|
|
bi-level image entity (BIE), decompresses it, and outputs a portable
|
|
bitmap (PBM) file.
|
|
|
|
.I 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
|
|
.I 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
|
|
.B -x
|
|
and
|
|
.B -y
|
|
can be used to stop the decompression at a specified maximal output
|
|
image size. With option
|
|
.B -m
|
|
the input file can consist of multiple 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.
|
|
.SH OPTIONS
|
|
.TP 12
|
|
.B \-
|
|
A single hyphen instead of an input file name will cause
|
|
.I jbgtopbm
|
|
to read the data from standard input instead from a file.
|
|
.TP
|
|
.BI \-x " number"
|
|
Decode only up to the largest resolution layer which is still not
|
|
more than
|
|
.I number
|
|
pixels wide. If no such resolution layer exists, then use the smallest
|
|
one available.
|
|
.TP
|
|
.BI \-y " number"
|
|
Decode only up to the largest resolution layer which is still not
|
|
more than
|
|
.I number
|
|
pixels high. If no such resolution layer exists, then use the smallest
|
|
one available. Options
|
|
.B \-x
|
|
and
|
|
.B \-y
|
|
can also be used together in which case the largest layer that satisfies
|
|
both limits will be selected.
|
|
.TP
|
|
.B \-m
|
|
Process multiple concatenated BIEs. If there are bytes left after the
|
|
final SDE in the first BIE, then with this option
|
|
.I 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.
|
|
.TP
|
|
.B \-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 bitplane 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.
|
|
.TP
|
|
.B \-d
|
|
Diagnose a single BIE. With this option,
|
|
.I 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.
|
|
.TP
|
|
.BI \-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.
|
|
.SH 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.
|
|
.SH STANDARDS
|
|
This program implements the
|
|
.I JBIG1
|
|
image coding algorithm as specified in international standard ISO/IEC
|
|
11544:1993 and ITU-T Recommendation T.82(1993).
|
|
.SH AUTHOR
|
|
Markus Kuhn wrote
|
|
.UR http://www.cl.cam.ac.uk/~mgk25/jbigkit/
|
|
.I JBIG-KIT
|
|
.UE ,
|
|
which includes
|
|
.IR jbgtopbm .
|
|
.SH SEE ALSO
|
|
pbm(5), pgm(5), pbmtojbg(1)
|