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<H1>ppmtopgm</H1>
Section: User Commands (1)<BR>Updated: 10 April 2000<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
ppmtopgm - convert a portable pixmap into a portable graymap
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<H2>SYNOPSIS</H2>
<B>ppmtopgm</B>
[<I>ppmfile</I>]
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<H2>DESCRIPTION</H2>
Reads a portable pixmap as input. Produces a portable graymap as
output. The output is a &quot;black and white&quot; rendering of the original
image, as in a black and white photograph. The quantization formula
used is .299 r + .587 g + .114 b.
<P>
Note that although there is a
<B>pgmtoppm</B>
program, it is not necessary for simple conversions from pgm to ppm ,
because any ppm program can read pgm (and pbm ) files automatically.
<B>pgmtoppm</B>
is for colorizing a pgm file. Also, see
<B>ppmtorgb3</B>
<A NAME="ixAAC"></A>
for a different way of converting color to gray. And
<B>ppmdist </B>
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.
<P>
<A NAME="lbAE">&nbsp;</A>
<H2>QUOTE</H2>
<PRE>
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.
</PRE>
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<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+pgmtoppm">pgmtoppm</A></B>(1),<B><A HREF="/cgi-bin/man/man2html?1+ppmtorgb3">ppmtorgb3</A></B>(1),<B><A HREF="/cgi-bin/man/man2html?1+rgb3toppm">rgb3toppm</A></B>(1),<B><A HREF="/cgi-bin/man/man2html?1+ppmdist">ppmdist</A></B>(1),<B><A HREF="/cgi-bin/man/man2html?5+ppm">ppm</A></B>(5),<B><A HREF="/cgi-bin/man/man2html?5+pgm">pgm</A></B>(5)
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<H2>AUTHOR</H2>
Copyright (C) 1989 by Jef Poskanzer.
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="1"><A HREF="#lbAB">NAME</A><DD>
<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="4"><A HREF="#lbAE">QUOTE</A><DD>
<DT id="5"><A HREF="#lbAF">SEE ALSO</A><DD>
<DT id="6"><A HREF="#lbAG">AUTHOR</A><DD>
</DL>
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