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 ▲
-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.