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       cjb2 - Simple DjVuBitonal encoder.


       cjb2  [options] inputfile outputdjvufile


       This  is a simple encoder for bitonal files.  Argument inputfile is the
       name of a PBM or bitonal TIFF file containing a single document  image.
       This program produces a DjVuBitonal file named outputdjvufile.

       The  default  compression process is lossless: decoding the DjVuBitonal
       file at full resolution will produce an image exactly identical to  the
       input  file.   Lossy  compression  is  enabled  by  options -losslevel,
       -lossy, or -clean.


       -dpi n Specify the resolution information encoded into the output  file
              expressed  in  dots per inch. The resolution information encoded
              in DjVu files determine how the decoder scales the  image  on  a
              particular  display.   Meaningful  resolutions  range from 25 to
              1200.  The default resolution for TIFF files is  the  resolution
              is  the  resolution  specified  by  the input file.  The default
              resolution for PBM files is 300 dpi.

              Ensure that the encoded image is pixel-per-pixel  equal  to  the
              initial image.  This option is is equivalent to -losslevel 0 and
              is the default.

       -clean Only remove flyspecks from the input image.  This option enables
              a heuristic algorithm that removes very small marks.  Such marks
              are often causes by noise and dust during the scanning  process.
              The  threshold  mark  size is chosen according to the resolution
              specified with option This option is is equivalent to -losslevel

       -lossy Substitute  patterns  with small variations.  In addition to the
              flyspeck removal heuristic, this  option  enables  an  algorithm
              that  encodes certain characters by simply replicating the shape
              of a previously encoded character with a  similar  shape.   This
              option is is equivalent to -losslevel 100.

       -losslevel x
              Specify  the  aggressiveness  of  the  lossy  compression.   Its
              argument ranges from 0 to 200.  Higher values  generate  smaller
              files with more potential distortions.  Loss level 0 corresponds
              to lossless encoding.  Loss level 1 performs image cleaning  but
              does  not perform character substitution at all.  Loss level 100
              is intended to provide a good compromise.   Higher  loss  levels
              provide   marginally   better   compression   at   the  risk  of
              unacceptable character substitutions.

              Display informational messages while running.


       Lossless encoding is competitive with that of the Lizardtech commercial

       Lossy encoding is making much progress thanks to Ilya Mezhirov from the
       minidjvu project.  This also means that the lossy encoding  performance
       can  change  from  version  to  version.  When lossy compression yields
       inadequate results, simply revert to only using option -clean or reduce
       the parameter of option -losslevel.

       Two features are still missing:

       *  Half-tone  detection.  Collecting small marks belonging to half-tone
          patterns would improve compression speed.

       *  Multi-page compression. Matching characters on several  pages  would
          improve the compression ratios for multi-page documents.


       This     program    was    initially    written    by    Leon    Bottou
       <>  and  was  improved   by   Bill   Riemers
       <>   and  many  others.   The  pattern  matching
       algorithm for  lossy  compression  was  contributed  by  Ilya  Mezhirov
       <>.  TIFF input routines are inspired by the ones
       contributed by R. Keith Dennis <>  and  Paul


       djvu(1), pbm(5).