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Online Computer Terms Dictionary - P

PPM ==>

Portable Pixmap

<file format> (PPM) A colour image file format.

A PPM file contains the following:

 a two character "{magic number}" - "P3",
 the width in pixels,
 the height in pixels,
 the maximum colour component value,
 HEIGHT rows of WIDTH {pixels}.

The rows are ordered from top to bottom with the pixels in each row ordered from left to right. Each pixel is represented as three values for red, green, and blue.

All parts are separated by whitespace and numbers are in decimal ASCIII representation. A zero pixel component means that colour is absent. Characters from a "#" to the next end-of-line are ignored and 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

A "RAWBITS" variant has magic number "P6", pixel values are stored as plain binary bytes, instead of ASCII decimal and no whitespace is allowed after a single whitespace character after the maximum colour component value which must be less than or equal to 255.

(1998-02-06)

 


Nearby terms: Portable Network Graphics Portable Object Adapter Portable Operating System Interface Portable Pixmap Portable Scheme Debugger Portable Scheme Interpreter Portable Standard Lisp
 

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