Provided by: jbigkit-bin_2.1-3.1build1_amd64 bug

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
       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.  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 × 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
                     progressive mode into different BIEs. Options -l and -h allow 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
                     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
                     permitted  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  one  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
                     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 one 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
                     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 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
                     format  to  support  this.  The NEWLEN marker segment can override the image
                     height stated in the BIE header anywhere later in the data stream.  Normally
                     pbmtojbg  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
                     pbmtojbg  will  then  add  a  NEWLEN  marker  segment at the latest possible
                     opportunity to the data stream to signal the correct final height.

       -f            This option makes the output  file  comply  to  the  "facsimile  application
                     profile"  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)