PPM format description

This description is from the SGI's IFL man page. 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 x 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 maxed 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.

Viewing PPM files: free utilities to view and convert PPM files on PC can be found at
http://perso.wanadoo.fr/pierre.g/indexgb.html
On UNIX systems (Linux, Solaris, IRIX etc.) the program xv is typically installed, and most image viewers support ppm. if you have trouble viewing ppm files, let me know.

Denis Zorin