ppmtopgm
Section: User Commands (1)
Updated: 10 April 2000
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NAME
ppmtopgm - convert a portable pixmap into a portable graymap
SYNOPSIS
ppmtopgm
[ppmfile]
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.
QUOTE
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.
SEE ALSO
pgmtoppm(1),ppmtorgb3(1),rgb3toppm(1),ppmdist(1),ppm(5),pgm(5)
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- QUOTE
-
- SEE ALSO
-
- AUTHOR
-
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Time: 19:49:15 GMT, April 27, 2011