     JBGTOPBM(1)                                                     JBGTOPBM(1)
                                     2003-06-04

     NAME
          jbgtopbm - JBIG1 to portable bitmap file converter

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

     DESCRIPTION
          Reads in a JBIG1 bi-level image entity (BIE) from a file or standard
          input, decompresses it, and outputs a portable bitmap (PBM) 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 in one or
          several BIEs. All resolution layers except the lowest one are stored
          efficiently as differences to the next lower resolution layer. Options
          -x and -y can be used to stop the decompression at a specified maximal
          output image size. With option -m the input file can consist of
          multiple concatenated BIEs which contain different increasing
          resolution layers of the same image.

          If more than one bit per pixel is stored in the JBIG1 file, then a PGM
          file will be produced.

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

          -x number     Decode only up to the largest resolution layer which is
                        still not more than number pixels wide. If no such
                        resolution layer exists, then use the smallest one
                        available.

          -y number     Decode only up to the largest resolution layer which is
                        still not more than number pixels high. If no such
                        resolution layer exists, then use the smallest one
                        available. Options -x and -y can also be used together
                        in which case the largest layer that satisfies both
                        limits will be selected.

          -m            Process multiple concatenated BIEs. If there are bytes
                        left after the final SDE in the first BIE, then with
                        this option jbgtopbm will attempt to decode these as the
                        start of another BIE that may contain higher resolution
                        data. Normally, any remaining bytes will generate a
                        warning message.

          -b            Use binary values instead of Gray code words in order to
                        decode pixel values from multiple bitplanes. This option

                                        - 1 -     Formatted:  September 28, 2017

     JBGTOPBM(1)                                                     JBGTOPBM(1)
                                     2003-06-04

                        has only an effect if the input has more than one
                        bitplane and a PGM output file is produced.  Note that
                        the decoder has to be used in the same mode as the
                        encoder and cannot determine from the BIE, whether Gray
                        or binary code words were used by the encoder.

          -d            Diagnose a single BIE. With this option, jbgtopbm will
                        print a summary of the header information found in the
                        input file, followed by a list of all PSCD and ESC
                        marker sequences encountered until the end of the file
                        is reached.

          -p number     If the input contains multiple bitplanes, then extract
                        only the specified single plane as a PBM file. The first
                        plane has number 0.

     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 jbgtopbm 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), pbmtojbg(1)

                                        - 2 -     Formatted:  September 28, 2017