ppmtopgm

   Updated: 10 April 2000
   Table Of Contents

NAME

   ppmtopgm - convert a PPM image to a PGM image

SYNOPSIS

   ppmtopgm [ppmfile]

DESCRIPTION

   This program is part of Netpbm.

   ppmtopgm  reads  a  PPM as input and produces a PGM as output.
The output is a
   "black and white" rendering of the original	image,	as  in	a
black and white
   photograph. The quantization formula ppmtopgm uses is g = .299
r + .587 g +
   .114 b.

   Note that although there is a pgmtoppm program, it is not nec-
essary 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, ppmtorgb3, rgb3toppm, ppmdist, ppm, pgm

AUTHOR

   Copyright (C) 1989 by Jef Poskanzer.
     _________________________________________________________________



Table Of Contents

     * NAME
     * SYNOPSIS
     * DESCRIPTION
     * QUOTE
     * SEE ALSO
     * AUTHOR

UNIX/Linux commands referenced on this page:

1. convert
2. as
3. pgmtoppm
4. ppmtorgb3
5. which
6. rgb3toppm
7. ppmdist