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JBGTOPBM(1)		    General Commands Manual		   JBGTOPBM(1)

NAME
       jbgtopbm	- JBIG1	to portable bitmap file	converter

SYNOPSIS
       jbgtopbm	[ 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 se-
		     lected.

       -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  in-
       serted 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 ALSO
       pbm(5), pgm(5), pbmtojbg(1)

				  2003-06-04			   JBGTOPBM(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | BUGS | STANDARDS | AUTHOR | SEE ALSO

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