pbm(5)                                                     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.




                        27 September 1991                       1





pbm(5)                                                     pbm(5)


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

       - 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), pnm-
       toascii(1),  pbmtoatk(1),  pbmtobbnbg(1),   pbmtocmuwm(1),
       pbmtoepson(1), pbmtog3(1), pbmtogem(1), pbmtogo(1), pbmto-
       icon(1),  pbmtolj(1),  pbmtomacp(1),   pbmtomgr(1),   pbm-
       topi3(1),  pbmtoplot(1),  pbmtoptx(1), pbmtox10bm(1), pbm-
       toxbm(1),  pbmtoybm(1),  pbmtozinc(1),  pbmlife(1),   pbm-
       make(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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