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  • LINUX man pages
  • Linux Man Page Viewer


    The following form allows you to view linux man pages.

    Command:

    pbm

    
    
    

    DESCRIPTION

           The  portable  bitmap  format is a lowest common denominator monochrome
           file format.  It serves as the common language of  a  large  family  of
           bitmap  conversion  filters.   Because the format pays no heed to effi-
           ciency, it is simple and general enough that  one  can  easily  develop
           programs  to  convert to and from just about any other graphics format,
           or to manipulate the image.
    
           This is not a format that one would normally use to store a file or  to
           transmit  it to someone -- it's too expensive and not expressive enough
           for that.  It's just an intermediary format.  In it's  purest  use,  it
           lives only in a pipe between two other programs.
    
           The format definition is as follows.
    
           A  PBM file consists of a sequence of one or more PBM images. There are
           no data, delimiters, or padding before, after, or between images.
    
           Each PBM image consists of the following:
    
           - A "magic number" for identifying the file type.  A pbm image's  magic
             number is the two characters "P4".
    
           - Whitespace (blanks, TABs, CRs, LFs).
    
           - The  width  in  pixels of the image, formatted as ASCII characters in
             decimal.
    
           - Whitespace.
    
           - The height in pixels of the image, again in ASCII decimal.
    
           - Newline or other single whitespace character.
    
           - A raster of Height rows, in order from top to bottom.   Each  row  is
             Width  bits, packed 8 to a byte, with don't care bits to fill out the
             last byte in the row.  Each bit represents a pixel: 1 is black, 0  is
             white.  The order of the pixels is left to right.  The order of their
             storage within each file byte is most significant bit to  least  sig-
             nificant  bit.   The order of the file bytes is from the beginning of
             the file toward the end of the file.
    
           - Characters  from  a  "#"  to  the  next   end-of-line,   before   the
             width/height line, are comments and are ignored.
    
           There  is  actually  another  version of the PBM format, even more more
           simplistic, more lavishly wasteful of space than PBM, called Plain PBM.
           Plain PBM actually came first, but even its inventor couldn't stand its
           recklessly squanderous use of resources after a while and  switched  to
           what we now know as the regular PBM format.  But Plain PBM is so redun-
           dant -- so overstated -- that it's virtually impossible to break.   You
           can  send it through the most liberal mail system (which was the origi-
    
           - White space in the raster section is ignored.
    
           - You  can  put any junk you want after the raster, if it starts with a
             white space character.
    
           - No line should be longer than 70 characters.
    
           Here is an example of a small bitmap in the plain PBM format:
           P1
           # feep.pbm
           24 7
           0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
           0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 1 1 1 0
           0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0
           0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 1 0
           0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0
           0 1 0 0 0 0 0 1 1 1 1 0 0 1 1 1 1 0 0 1 0 0 0 0
           0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
    
           You can generate the Plain PBM  format  from  the  regular  PBM  format
           (first image in the file only) with the pnmtoplainpnm program.
    
           Programs  that  read  this  format  should  be  as lenient as possible,
           accepting anything that looks remotely like a bitmap.
    
    
    

    COMPATIBILITY

           Before July 2000, there could be at most one image in a PBM file.  As a
           result,  most  tools  to  process PBM files ignore (and don't read) any
           data after the first image.
    
    
    

    SEE ALSO

           libpbm(3),pnm(5),pgm(5),ppm(5)
    
    
    

    AUTHOR

           Copyright (C) 1989, 1991 by Jef Poskanzer.
    
                                     05 March 2000                          pbm(5)
    
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