jbgtopbm(1)

NAME

       jbgtopbm - JBIG to portable bitmap file converter

SYNOPSIS

       jbgtopbm [ options ] [ input-file | -  [ output-file ]]

DESCRIPTION

       Reads  in  a  JBIG  bi-level image entity (BIE) from a file or standard
       input, decompresses it, and outputs a portable bitmap (PBM) file.

       JBIG is a highly effective lossless compression algorithm for  bi-level
       images  (one bit per pixel), which is particularly suitable for scanned
       document pages.

       A JBIG 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. The input file can consist of  several  concatenated
       BIEs  which  contain different increasing resolution layers of the same
       image.

       If more than one bit per pixel is stored in the JBIG 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.

       -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  BIE.  With  this  option, jbgtopbm will only
                     print a summary of the header information  found  in  the
                     input file and then exit.

       -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 JBIG 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
       JBIG library and tools set is freely available  on  the  Internet  from
       anonymous   ftp   server  ftp.informatik.uni-erlangen.de  in  directory
       pub/doc/ISO/JBIG/. Bug reports should be sent to <mkuhn@acm.org>.

SEE ALSO

       pbm(5), pgm(5), pbmtojbg(1)

                                  1998-04-10                       JBGTOPBM(1)