1. NAME▲

ppmtopgm - convert a portable pixmap into a portable graymap

2. SYNOPSIS ▲

ppmtopgm [ ppmfile ]

3. DESCRIPTION ▲

Reads a portable pixmap as input. Produces a portable graymap as output. The output is a "black and white" rendering of the original image, as in a black and white photograph. The quantization formula used is .299 r + .587 g + .114 b.

Note that although there is a

pgmtoppm program, it is not necessary for simple conversions from pgm to ppm , because any ppm program can read pgm (and pbm ) files automatically.

pgmtoppm is for colorizing a pgm file. Also, see

ppmtorgb3 for a different way of converting color to gray. And

ppmdist generates a grayscale image from a color image, but in a way that makes it easy to differentiate the original colors, not necessarily a way that looks like a black and white photograph.

4. QUOTE ▲

 
Sélectionnez
Cold-hearted orb that rules the night
Removes the colors from our sight
Red is gray, and yellow white
But we decide which is right
And which is a quantization error.

5. SEE ALSO ▲

R pgmtoppm (1), ppmtorgb3 (1), rgb3toppm (1), ppmdist (1), ppm (5), pgm (5)

6. AUTHOR ▲

Copyright (C) 1989 by Jef Poskanzer.