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 ), 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 one 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    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

netpbm documentation                              28 July 2020                          Pnmtojbig User Manual(1)