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CentOS 7.0 - man page for pnmtojbig (centos section 0)

Pnmtojbig User Manual(0)						 Pnmtojbig User Manual(0)

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 reso-
       lution layers can be stored all in one single BIE or they can be stored in  several  sepa-
       rate  BIE files.  All resolution layers except the lowest one are stored merely as differ-
       ences 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 hori-
       zontal 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
       -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	x
	      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 inter-
	      val 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 neigh-
	      bor  pixel  which has a distance large enough to cover the period of a dither func-
	      tion.  By default, the adaptive template pixel can be moved up to  8  pixels  away.
	      This  encoder  supports  up  to 23 pixels, however as decoders are only required to
	      support 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 rel-
	      evant 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 reso-
	      lution 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 continu-
	      ing 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  implementa-
	      tions)  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  back-
       ground.	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
       If you use pnmtojbig, you are using various patents, particularly on its arithmetic encod-
       ing method, and in all probability you do not have a license from the patent owners to  do
       so.

netpbm documentation			   20 May 2000			 Pnmtojbig User Manual(0)


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