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PPMTOPGM.MAN
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1991-08-11
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ppmtopgm(1) Unix Programmer's Manual ppmtopgm(1)
NNNAAAMMMEEE
ppmtopgm - convert a portable pixmap into a portable graymap
SSSYYYNNNOOOPPPSSSIIISSS
ppppppmmmtttooopppgggmmm [_p_p_m_f_i_l_e]
DDDEEESSSCCCRRRIIIPPPTTTIIIOOONNN
Reads a portable pixmap as input. Produces a portable graymap 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.
QQQUUUOOOTTTEEE
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.
SSSEEEEEE AAALLLSSSOOO
pgmtoppm(1), ppmtorgb3(1), rgb3toppm(1), ppm(5), pgm(5)
AAAUUUTTTHHHOOORRR
Copyright (C) 1989 by Jef Poskanzer.
23 December 1988 1