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Section: User Commands (1)
jbgtopbm - JBIG1 to portable bitmap file converter
| - [output-file
Reads in a JBIG1
bi-level image entity (BIE) from a file or standardinput, decompresses it, and outputs a portable bitmap (PBM) file.
JBIG1is a highly effective lossless compression algorithm forbi-level images (one bit per pixel), which is particularly suitablefor scanned document pages.
AJBIG1encoded image can be stored in several resolutions in one or severalBIEs. All resolution layers except the lowest one are storedefficiently as differences to the next lower resolution layer. Options-xand-ycan be used to stop the decompression at a specified maximal outputimage size. With option-mthe input file can consist of multiple concatenated BIEswhich contain different increasing resolution layers of the sameimage.
If more than one bit per pixel is stored in the JBIG1 file, then a PGMfile will be produced.
- A single hyphen instead of an input file name will cause jbgtopbmto read the data from standard input instead from a file.
- -x number
- Decode only up to the largest resolution layer which is still notmore thannumberpixels wide. If no such resolution layer exists, then use the smallestone available.
- -y number
- Decode only up to the largest resolution layer which is still notmore thannumberpixels high. If no such resolution layer exists, then use the smallestone available. Options-xand-ycan also be used together in which case the largest layer that satisfiesboth limits will be selected.
- Process multiple concatenated BIEs. If there are bytes left after thefinal SDE in the first BIE, then with this optionjbgtopbmwill attempt to decode these as the start of another BIE that maycontain higher resolution data. Normally, any remaining bytes willgenerate a warning message.
- Use binary values instead of Gray code words in order to decode pixelvalues from multiple bitplanes. This option has only an effect if theinput 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 encoderand cannot determine from the BIE, whether Gray or binary code wordswere used by the encoder.
- Diagnose a single BIE. With this option,jbgtopbmwill print a summary of the header information found in the inputfile, followed by a list of all PSCD and ESC marker sequencesencountered until the end of the file is reached.
- -p number
- If the input contains multiple bitplanes, then extract only thespecified single plane as a PBM file. The first plane has number 0.
Using standard input and standard output for binary data works only onsystems where there is no difference between binary and text streams(e.g., Unix). On other systems (e.g., MS-DOS), using standard input orstandard output may cause control characters like CR or LF to beinserted or deleted and this will damage the binary data.
This program implements theJBIG1
image coding algorithm as specified in ISO/IEC 11544:1993 andITU-T T.82(1993).
program is part of the JBIG-KIT
package, which has been developed by Markus Kuhn.The most recent version of thisportableJBIG1
library and tools set is available from<http://www.cl.cam.ac.uk/~mgk25/jbigkit/
- SEE ALSO
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