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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
| commit | 1017cbebe5d5edd859e0fddad0a8600f509f4821 (patch) | |
| tree | 78bdf336648566f7a7d55f42837357dea3dd674c /pbmtopgm.html | |
| parent | 16f2ac126651015a376eba864a3a35f738b0b25a (diff) | |
| download | netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.gz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.xz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.zip | |
Place user guide into Subversion repository
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@181 9d0c8265-081b-0410-96cb-a4ca84ce46f8
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diff --git a/pbmtopgm.html b/pbmtopgm.html new file mode 100644 index 00000000..f68dfcad --- /dev/null +++ b/pbmtopgm.html @@ -0,0 +1,84 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML><HEAD><TITLE>Pbmtopgm User Manual</TITLE></HEAD> +<BODY> + +<H1>pbmtopgm</H1> +<p>Updated: 05 Feb 2003 + +<A HREF="#index">Table Of Contents</A> + +<A NAME="lbAB"> </A> +<H2>NAME</H2> +pbmtopgm - convert PBM image to PGM by averaging areas + +<A NAME="lbAC"> </A> +<H2>SYNOPSIS</H2> + +<B>pbmtopgm </B> +<I>width</I> +<I>height</I> +[<I>pbmfile</I>] + +<A NAME="lbAD"> </A> +<H2>DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<P><B>pbmtopgm</B> reads a PBM image as input. It outputs a PGM image +in which each pixel's gray level is the average of the surrounding +black and white input pixels. The surrounding area is a rectangle of +<I>width</I> by <I>height</I> pixels. + +<P>In other words, this is a convolution. <B>pbmtopgm</B> is similar +to a special case of <B>pnmconvol</B>. + +<P>You may need a <B>pnmsmooth</B> step after <B>pbmtopgm</B>. + +<P><B>pbmtopgm</B> has the effect of anti-aliasing bitmaps which +contain distinct line features. + +<P><B>pbmtopgm</B> works best with odd sample width and heights. + +<P>You don't need <B>pbmtopgm</B> just to use a PGM program on a PBM +image. Any PGM program (assuming it uses the Netpbm libraries to read +the PGM input) takes PBM input as if it were PGM, with only the +mininum and maximum gray levels. So unless your convolution rectangle +is bigger than one pixel, you're not gaining anything with a +<B>pbmtopgm</B> step. + +<p>The opposite transformation (which would turn a PGM into a PBM) is +dithering. See <b>pamditherbw</b>. + +<A NAME="lbAE"> </A> +<H2>SEE ALSO</H2> + +<B><A HREF="pamditherbw.html">pamditherbw</A></B>, +<B><A HREF="pnmconvol.html">pnmconvol</A></B>, +<B><A HREF="pbm.html">pbm</A></B>, +<B><A HREF="pgm.html">pgm</A></B> + +<A NAME="lbAF"> </A> +<H2>AUTHOR</H2> + +<P>Copyright (C) 1990 by Angus Duggan. +<P>Copyright (C) 1989 by Jef Poskanzer. + +<P>Permission to use, copy, modify, and distribute this software and +its documentation for any purpose and without fee is hereby granted, +provided that the above copyright notice appear in all copies and that +both that copyright notice and this permission notice appear in +supporting documentation. This software is provided "as is" +without express or implied warranty. + +<HR> +<A NAME="index"> </A> +<H2>Table Of Contents</H2> +<UL> +<LI><A HREF="#lbAB">NAME</A> +<LI><A HREF="#lbAC">SYNOPSIS</A> +<LI><A HREF="#lbAD">DESCRIPTION</A> +<LI><A HREF="#lbAE">SEE ALSO</A> +<LI><A HREF="#lbAF">AUTHOR</A> +</UL> +</BODY> +</HTML> |