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ppmtopgm.1
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1994-08-27
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ppmtopgm(1) USER COMMANDS ppmtopgm(1)
NAME
ppmtopgm - convert a portable pixmap into a portable graymap
SYNOPSIS
ppmtopgm [_✓p_✓p_✓m_✓f_✓i_✓l_✓e]
DESCRIPTION
Reads a portable pixmap as input. Produces a portable gray-
map as output. The quantization formula used is .299 r +
.587 g + .114 b.
Note that although there is a _✓p_✓g_✓m_✓t_✓o_✓p_✓p_✓m program, it is not
necessary for simple conversions from _✓p_✓g_✓m to _✓p_✓p_✓m, because
any ppm program can read _✓p_✓g_✓m (and _✓p_✓b_✓m ) files automagically.
_✓p_✓g_✓m_✓t_✓o_✓p_✓p_✓m is for colorizing a _✓p_✓g_✓m file. Also, see _✓p_✓p_✓m_✓t_✓o_✓r_✓g_✓b_✓3
for a different way of converting color to gray.
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), ppm(5), pgm(5)
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
Sun Release 4.0 Last change: 23 December 1988 1