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CentOS 7.0 - man page for pbmtojbg (centos section 1)

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PBMTOJBG(1)									      PBMTOJBG(1)

NAME
       pbmtojbg - portable bitmap to JBIG1 file converter

SYNOPSIS
       pbmtojbg [ options ] [ input-file | -  [ output-file ]]

DESCRIPTION
       Reads in a portable bitmap (PBM) from a file or standard input, compresses it, and outputs
       the image as a JBIG1 bi-level image entity (BIE) file.

       JBIG1 is a highly effective lossless compression algorithm for bi-level	images	(one  bit
       per pixel), which is particularly suitable for scanned document pages.

       A JBIG1 encoded image can be stored in several resolutions (progressive mode).  These res-
       olution 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.  JBIG1 files can also store  several
       bits  per  pixel as separate bitmap planes, and pbmtojbg can read a PGM file and transform
       it into a multi-bitplane BIE.

OPTIONS
       -	     A single hyphen instead of an input file name will cause  pbmtojbg  to  read
		     the data from standard input instead from a file.

       -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. This is a shortcut for -d 0.

       -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 JBIG1 image in progres-
		     sive mode into different BIEs. Options -l and -h allow to select the resolu-
		     tion-layer  interval that will appear in the created BIE. The lowest resolu-
		     tion layer has number 0 and this is also the default value. By  default  all
		     layers will be written.

       -h number     Select  the  highest  resolution  layer  that will be written to the BIE. By
		     default all layers will be written. 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 JBIG1 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
		     JBIG1 encoder uses ten neighbour pixels to estimate the probability  of  the
		     next  pixel  being  black or white. It can move one out of these ten pixels.
		     This is especially useful for dithered images, as long as	the  distance  of
		     this  adaptive pixel can be adjusted to the period of the dither pattern. By
		     default, the adaptive template pixel is allowed to move up to 8 pixels  away
		     horizontally.  This  encoder supports distances up to 127 pixels. Annex A of
		     the standard suggests that decoders should support  at  least  a  horizontal
		     distance  of  16 pixels, so using values not higher than 16 for number might
		     increase the chances of interoperability with other  JBIG1  implementations.
		     On  the  other  hand,  the T.85 fax application profile requires decoders to
		     support horizontal offsets up to 127 pixels, which the maximum value permit-
		     ted  by  the standard. (The maximal vertical offset of the adaptive template
		     pixel is always zero for this encoder.)

       -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     JBIG1 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 JBIG1 file which has not yet completely arrived from  e.g.  a  slow
		     network  connection.   For instance some applications prefer that the outer-
		     most 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 to activate or	deactivate  various  optional  algorithms
		     defined in the JBIG1 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      layer 0 typical prediction (TPBON)
		       16      diff. layer typ. pred. (TPDON)
		       64      layer 0 two-line template (LRLTWO)

		     Except for special applications (like communication with JBIG1 subset imple-
		     mentations)  and for debugging purposes you will normally not want to change
		     anything here. The default  is  28,  which  provides  the	best  compression
		     result.

       -C string     Add  the  string  in  a  comment marker segment to the produced data stream.
		     (There is no support at present for adding comments that  contain	the  zero
		     byte.)

       -c	     Determine	the  adaptive  template pixel movement 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
		     tests.

       -r	     Use  the SDRST marker instead of the normal SDNORM marker. The probably only
		     useful application of this option is to  generate	test  data  for  checking
		     whether  a  JBIG1 decoder has implemented SDRST correctly. In a normal JBIG1
		     data stream, each stripe data  entity  (SDE)  is  terminated  by  an  SDNORM
		     marker,  which  preserves the state of the arithmetic encoder (and more) for
		     the next stripe in the same layer. The alternative SDRST marker resets  this
		     state at the end of the stripe.

       -Y number     A	long  time  ago, there were fax machines that couldn't even hold a single
		     page in memory. They had to start transmitting  data  before  the	page  was
		     scanned in completely and the length of the image was known.  The authors of
		     the standard added a rather ugly hack to the otherwise beautiful JBIG1  for-
		     mat to support this. The NEWLEN marker segment can override the image height
		     stated in the BIE header anywhere later in the data stream. Normally  pbmto-
		     jbg  never  generates  NEWLEN marker segments, as it knows the correct image
		     height when it outputs the header. This option is solely  intended  for  the
		     purpose of generating test files with NEWLEN marker segments. It can be used
		     to specify a higher initial image height for use in the BIE header, and pbm-
		     tojbg  will then add a NEWLEN marker segment at the latest possible opportu-
		     nity to the data stream to signal the correct final height.

       -f	     This option makes the output file comply to the "facsimile application  pro-
		     file"  defined in ITU-T Recommendation T.85. It is a shortcut for -q -o 0 -p
		     8 -s 128 -t 1 -m 127.

       -v	     After the BIE has been created, a few technical details of the created  file
		     will be listed (verbose mode).

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  JBIG1  image  coding  algorithm  as  specified  in  ISO/IEC
       11544:1993 and ITU-T T.82(1993).

AUTHOR
       The  pbmtojbg  program is part of the JBIG-KIT package, which has been developed by Markus
       Kuhn.  The most recent version of this portable JBIG1 library and tools set  is	available
       from <http://www.cl.cam.ac.uk/~mgk25/jbigkit/>.

SEE ALSO
       pbm(5), pgm(5), jbgtopbm(1)

					    2003-06-04				      PBMTOJBG(1)
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