Provided by: netpbm_11.01.00-2build1_amd64 bug

NAME

       pnmtojbig - PNM to JBIG file converter

SYNOPSIS

       pnmtojbig

       [options] [input-file [output-file]]

DESCRIPTION

       This program is part of Netpbm(1).

       pnmtojbig  reads  a  PBM  or PGM image, compresses it, and outputs the image as a JBIG bi-
       level image entity (BIE) 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 (progressive mode).  These
       resolution layers can be stored all in one single BIE or they can  be  stored  in  several
       separate  BIE  files.   All  resolution  layers except the lowest one are stored merely as
       differences to the next lower resolution layer, because  this  requires  less  space  than
       encoding  the full image completely every time. Each resolution layer has twice the number
       of horizontal and vertical pixels than the next lower layer.  JBIG files  can  also  store
       several  bits  per  pixel as separate bitmap planes, and pnmtojbig can read a PGM file and
       transform it into a multi-bitplane BIE.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common  Options  ⟨index.html#commonoptions⟩ ), pnmtojbig recognizes the following command
       line options:

       -q     Encode the image in one single resolution layer (sequential mode). This is  usually
              the  most efficient compression method. By default, the number of resolution layers
              is chosen automatically such that the lowest layer image is not larger than  640  ×
              480 pixels.

       -x number
              Specify the maximal horizontal size of the lowest resolution layer.  The default is
              640 pixels.

       -y number
              Specify the maximal vertical size of the lowest resolution layer.  The  default  is
              480 pixels.

       -l number
              Select the lowest resolution layer that will be written to the BIE.  It is possible
              to store the various resolution layers of a JBIG image  in  progressive  mode  into
              different  BIEs.   Options  -l  and  -h  allow  you  to select the resolution-layer
              interval that will appear in the created BIE.   The  lowest  resolution  layer  has
              number  0  and  this  is  also the default value.  By default, pnmtojbig writes all
              layers.

       -h number
              Select the highest resolution layer that will be written to the BIE.   By  default,
              pnmtojbig writes all layers.  See also option -l.

       -b     Use  binary  values  instead  of Gray code words in order to encode pixel values in
              multiple bitplanes.  This option has only an effect if the input is a PGM file  and
              if  more  than one bitplane is produced. Note that the decoder has to make the same
              selection but cannot determine from the BIE, whether Gray or binary code words were
              used by the encoder.

       -d number
              Specify  the  total  number  of differential resolution layers into which the input
              image will be split in addition to the lowest layer.  Each additional layer reduces
              the  size  of  layer 0 by 50 %.  This option overrides options -x and -y, which are
              usually a more comfortable way of selecting the number of resolution layers.

       -s number
              The JBIG algorithm splits each image into a number  of  horizontal  stripes.   This
              option  specifies that each stripe shall have number lines in layer 0.  The default
              value is selected so that approximately 35 stripes  will  be  used  for  the  whole
              image.

       -m number
              Select  the  maximum  horizontal  offset  of the adaptive template pixel.  The JBIG
              encoder uses a number of neighbour pixels in order  to  get  statistical  a  priori
              knowledge  of  the probability, whether the next pixel will be black or white.  One
              single pixel out of this template of context neighbor pixels can be  moved  around.
              Especially  for  dithered  images  it  can  be  a significant advantage to have one
              neighbor pixel which has a distance large enough to cover the period  of  a  dither
              function.   By  default,  the  adaptive  template pixel can be moved up to 8 pixels
              away.  This encoder go up to 23 pixels, however as decoders are  only  required  to
              handle  at  least  a distance of 16 pixels by the standard, no higher value than 16
              for number is recommended in order to maintain  interoperability  with  other  JBIG
              implementations.   The  maximal  vertical  offset of the adaptive template pixel is
              always zero.

       -t number
              Encode only the specified number of  most  significant  bit  planes.   This  option
              allows  to  reduce  the  depth  of  an input PGM file if not all bits per pixel are
              needed in the output.

       -o number
              JBIG separates an image into several  horizontal  stripes,  resolution  layers  and
              planes, were each plane contains one bit per pixel.  One single stripe in one plane
              and layer is encoded as a data unit called stripe data entity (SDE) inside the BIE.
              There  are  12 different possible orders in which the SDEs can be stored inside the
              BIE and number selects which one shall be used.  The order  of  the  SDEs  is  only
              relevant  for  applications  that  want  to  decode  a  JBIG file which has not yet
              completely arrived  from  e.g.  a  slow  network  connection.   For  instance  some
              applications prefer that the outermost of the three loops (stripes, layers, planes)
              is over all layers so that all data of the lowest resolution layer  is  transmitted
              first.

              The following values for number select these loop arrangements for writing the SDEs
              (outermost loop first):

       0      planes, layers, stripes

       2      layers, planes, stripes

       3      layers, stripes, planes

       4      stripes, planes, layers

       5      planes, stripes, layers

       6      stripes, layers, planes

              All loops count starting with zero, however by adding 8 to the  above  order  code,
              the  layer  loop  can  be  reversed  so that it counts down to zero and then higher
              resolution layers will be stored before lower layers.  Default  order  is  3  which
              writes  at  first  all planes of the first stripe and then completes layer 0 before
              continuing with the next layer and so on.

       -p number
              This option allows you  to  activate  or  deactivate  various  optional  algorithms
              defined  in the JBIG standard.  Just add the numbers of the following options which
              you want to activate in order to get the number value:

       4      deterministic prediction (DPON)

       8      typical prediction (TPBON)

       16     diff. layer typical prediction (TPDON)

       64     layer 0 two-line template (LRLTWO)

              Except  for   special   applications   (like   communication   with   JBIG   subset
              implementations)  and  for  debugging purposes you will normally not want to change
              anything here.  The default is 28, which provides the best compression result.

       -c     The adaptive template pixel movement is determined as suggested in annex C  of  the
              standard.   By  default  the  template change takes place directly in the next line
              which is most effective.  However a few conformance test examples in  the  standard
              require the adaptive template change to be delayed until the first line of the next
              stripe.  This option selects this special behavior, which is normally not  required
              except in order to pass some conformance test suite.

       -v     After  pnmtojbig  creates  the BIE, it lists a few technical details of the created
              file (verbose mode).

FORMATS

       Most of the format pnmtojbig creates is defined by the JBIG standard.

       The standard, however, does not specify which values in the BIE mean white and which  mean
       black.   It  contains  a recommendation that for a single plane image zero mean background
       and one mean foreground, but  the  Netpbm  formats  have  no  concept  of  foreground  and
       background.  And the standard says nothing about values for multiple plane BIEs.

       pnmtojbig  follows  Markus  Kuhn's  implementation of the standard in the pbmtojbg program
       that comes with his JBIG library:  If the BIE is a single plane BIE, zero means white  and
       one means black.  If it is a multiple plane BIE, zero means black and the maximal value is
       white.

STANDARDS

       This program implements the JBIG image coding algorithm as specified in ISO/IEC 11544:1993
       and ITU-T T.82(1993).

AUTHOR

       pnmtojbig  is based on the JBIG library by Markus Kuhn, part of his JBIG-KIT package.  The
       pbmtojbg program is part of the JBIG-KIT package.  The most recent version of that library
       and   tools   set   is  freely  available  on  the  Internet  from  anonymous  ftp  server
       ftp.informatik.uni-erlangen.de  ⟨ftp://ftp.informatik.uni-erlangen.de⟩      in   directory
       pub/doc/ISO/JBIG/.

       pnmtojbig is part of the Netpbm package of graphics tools.

SEE ALSO

       pnm(1), jbigtopnm(1)

LICENSE

       There was at one time concern about the need for patent licenses to use pnmtojbig, but any
       relevant patents expired by 2012.

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master
       documentation is at

              http://netpbm.sourceforge.net/doc/pnmtojbig.html