.TH ppmtopgm 1 "23 December 1988"
.IX ppmtopgm
.SH NAME
ppmtopgm - convert a portable pixmap into a portable graymap
.SH SYNOPSIS
.B ppmtopgm
.RI [ ppmfile ]
.SH DESCRIPTION
Reads a portable pixmap as input.
Produces a portable graymap as output.
The quantization formula used is .299 r + .587 g + .114 b.
.PP
Note that although there is a
.I pgmtoppm
program, it is not necessary
for simple conversions from
.I pgm
to
.IR ppm ,
because any ppm program can
read
.I pgm
(and
.I pbm
) files automagically.
.I pgmtoppm
is for colorizing a
.I pgm
file.  Also, see
.I ppmtorgb3
.IX ppmtorgb3
for a different way of converting color to gray.
.SH QUOTE
.nf
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.
.fi
.SH "SEE ALSO"
pgmtoppm(1), ppmtorgb3(1), rgb3toppm(1), ppm(5), pgm(5)
.SH AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
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