pbm(5)                 UNIX System V(27 September 1991)                  pbm(5)


NAME
      pbm - portable bitmap file format

DESCRIPTION
      The portable bitmap format is a lowest common denominator monochrome file
      format.  It was originally designed to make it reasonable to mail bitmaps
      between different types of machines using the typical stupid network
      mailers we have today.  Now it serves as the common language of a large
      family of bitmap conversion filters.  The definition is as follows:

      - A "magic number" for identifying the file type.  A pbm file's magic
        number is the two characters "P1".

      - Whitespace (blanks, TABs, CRs, LFs).

      - A width, formatted as ASCII characters in decimal.

      - Whitespace.

      - A height, again in ASCII decimal.

      - Whitespace.

      - Width * height bits, each either '1' or '0', starting at the top-left
        corner of the bitmap, proceeding in normal English reading order.

      - The character '1' means black, '0' means white.

      - Whitespace in the bits section is ignored.

      - Characters from a "#" to the next end-of-line are ignored (comments).

      - No line should be longer than 70 characters.

      Here is an example of a small bitmap in this 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

      Programs that read this format should be as lenient as possible,
      accepting anything that looks remotely like a bitmap.

      There is also a variant on the format, available by setting the RAWBITS
      option at compile time.  This variant is different in the following ways:



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pbm(5)                 UNIX System V(27 September 1991)                  pbm(5)


      - The "magic number" is "P4" instead of "P1".

      - The bits are stored eight per byte, high bit first low bit last.

      - No whitespace is allowed in the bits section, and only a single
        character of whitespace (typically a newline) is allowed after the
        height.

      - The files are eight times smaller and many times faster to read and
        write.

SEE ALSO
      atktopbm(1), brushtopbm(1), cmuwmtopbm(1), g3topbm(1), gemtopbm(1),
      icontopbm(1), macptopbm(1), mgrtopbm(1), pi3topbm(1), xbmtopbm(1),
      ybmtopbm(1), pbmto10x(1), pnmtoascii(1), pbmtoatk(1), pbmtobbnbg(1),
      pbmtocmuwm(1), pbmtoepson(1), pbmtog3(1), pbmtogem(1), pbmtogo(1),
      pbmtoicon(1), pbmtolj(1), pbmtomacp(1), pbmtomgr(1), pbmtopi3(1),
      pbmtoplot(1), pbmtoptx(1), pbmtox10bm(1), pbmtoxbm(1), pbmtoybm(1),
      pbmtozinc(1), pbmlife(1), pbmmake(1), pbmmask(1), pbmreduce(1),
      pbmtext(1), pbmupc(1), pnm(5), pgm(5), ppm(5)

AUTHOR
      Copyright (C) 1989, 1991 by Jef Poskanzer.































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