pbm(5)			       File Formats Manual			  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 mail-
     ers 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 num-
       ber 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 op-
     tion 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), icon-
     topbm(1), macptopbm(1), mgrtopbm(1), pi3topbm(1), xbmtopbm(1), ybmtopbm(1),
     pbmto10x(1), pnmtoascii(1), pbmtoatk(1), pbmtobbnbg(1), pbmtocmuwm(1), pbm-
     toepson(1), pbmtog3(1), pbmtogem(1), pbmtogo(1), pbmtoicon(1),  pbmtolj(1),
     pbmtomacp(1),  pbmtomgr(1),  pbmtopi3(1),	pbmtoplot(1),  pbmtoptx(1), pbm-
     tox10bm(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.

				27 September 1991			  pbm(5)