ppm(5)

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 possible,
       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 char-
         acter of whitespace (typically a newline) is allowed after  the  max-
         val.

       - 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), picttoppm(1), pjtoppm(1), qrt-
       toppm(1),   rawtoppm(1),   rgb3toppm(1),   sldtoppm(1),    spctoppm(1),
       sputoppm(1),  tgatoppm(1),  ximtoppm(1), xpmtoppm(1), yuvtoppm(1), ppm-
       toacad(1), ppmtogif(1), ppmtoicr(1),  ppmtoilbm(1),  ppmtopcx(1),  ppm-
       topgm(1),  ppmtopi1(1),  ppmtopict(1),  ppmtopj(1),  ppmtopuzz(1), ppm-
       torgb3(1), ppmtosixel(1), ppmtotga(1), ppmtouil(1),  ppmtoxpm(1),  ppm-
       toyuv(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.

                               27 September 1991                        ppm(5)