
NAME
     ppm - portable pixmap file	format

DESCRIPTION
     The portable pixmap format	is a  lowest  common  denominator
     color image file format.  The definition is as follows:

     - A "magic	number"	for identifying	the  file  type.   A  ppm
       file's magic number is the two characters "P3".

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

     - A width,	formatted as ASCII characters in decimal.

     - Whitespace.

     - A height, again in ASCII	decimal.

     - Whitespace.

     - The maximum color-component value, again	in ASCII decimal.

     - Whitespace.

     - Width * height pixels, each  three  ASCII  decimal  values
       between 0 and the specified maximum value, starting at the
       top-left	 corner	 of  the  pixmap,  proceeding  in  normal
       English	reading	 order.	  The three values for each pixel
       represent red, green, and blue, respectively; a value of	0
       means  that color is off, and the maximum value means that
       color is	maxxed out.

     - 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 pixmap in this format:
     P3
     # feep.ppm
     4 4
     15
      0	 0  0	 0  0  0    0  0  0   15  0 15
      0	 0  0	 0 15  7    0  0  0    0  0  0
      0	 0  0	 0  0  0    0 15  7    0  0  0
     15	 0 15	 0  0  0    0  0  0    0  0  0

     Programs that read	this format should be as lenient as  pos-
     sible, accepting anything that looks remotely like	a pixmap.

     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:

     - The "magic number" is "P6" instead of "P3".

     - The pixel values	are stored as  plain  bytes,  instead  of
       ASCII decimal.

     - Whitespace is not allowed in the	pixels area, and  only	a
       single  character  of  whitespace (typically a newline) is
       allowed after the maxval.

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

     Note that this raw	format can only	be used	for maxvals  less
     than or equal to 255.  If you use the ppm library and try to
     write a file with a larger	 maxval,  it  will  automatically
     fall back on the slower but more general plain format.

SEE ALSO
     giftoppm(1),   gouldtoppm(1),   ilbmtoppm(1),   imgtoppm(1),
     mtvtoppm(1),  pcxtoppm(1),	 pgmtoppm(1),  pi1toppm(1), pict-
     toppm(1),	   pjtoppm(1),	   qrttoppm(1),	     rawtoppm(1),
     rgb3toppm(1),  sldtoppm(1),  spctoppm(1),	sputoppm(1), tga-
     toppm(1),	   ximtoppm(1),	    xpmtoppm(1),     yuvtoppm(1),
     ppmtoacad(1),    ppmtogif(1),   ppmtoicr(1),   ppmtoilbm(1),
     ppmtopcx(1),   ppmtopgm(1),    ppmtopi1(1),    ppmtopict(1),
     ppmtopj(1),   ppmtopuzz(1),   ppmtorgb3(1),   ppmtosixel(1),
     ppmtotga(1),    ppmtouil(1),    ppmtoxpm(1),    ppmtoyuv(1),
     ppmdither(1),     ppmforge(1),    ppmhist(1),    ppmmake(1),
     ppmpat(1),	  ppmquant(1),	 ppmquantall(1),    ppmrelief(1),
     pnm(5), pgm(5), pbm(5)

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

