115 lines
2.7 KiB
HTML
115 lines
2.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of pbmtopgm</TITLE>
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</HEAD><BODY>
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<H1>pbmtopgm</H1>
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Section: User Commands (1)<BR>Updated: 03 Sep 2001<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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pbmtopgm - convert portable bitmap to portable graymap by averaging areas
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<P>
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pbmtopgm </B>
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<I>width</I>
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<I>height</I>
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[<I>pbmfile</I>]
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<P>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<B>pbmtopgm</B>
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reads a portable bitmap as input. It outputs a portable graymap
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in which each pixel's gray level is the average the surrounding black
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and white input pixels. The surrounding area is a rectangle of
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<I>width</I>
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by
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<I>height</I>
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pixels.
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<P>
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In other words, this is a convolution.
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<B>pbmtopgm </B>
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is similar to a special case of
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<B>pnmconvol</B>.
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<P>
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You may need a
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<B>ppmsmooth</B>
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step after
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<B>pbmtopgm</B>.
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<P>
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<B>pbmtopgm </B>
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has the effect of anti-aliasing bitmaps which contain distinct line
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features.
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<P>
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<B>pbmtopgm </B>
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works best with odd sample width and heights.
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<P>
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You don't need
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<B>pbmtopgm</B>
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just to use a PGM program on a PBM image. Any PGM program (assuming it uses
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the Netpbm libraries to read the PGM input) takes PBM input as if it were
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PGM, with only the mininum and maximum gray levels. So unless your convolution
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rectangle is bigger than one pixel, you're not gaining anything with a
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<B>pbmtopgm</B>
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step.
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<P>
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<A NAME="lbAE"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?1+netpbm">netpbm</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?1+pgmtopbm">pgmtopbm</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?5+pbm">pbm</A></B>(5)
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<P>
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<A NAME="lbAF"> </A>
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<H2>AUTHOR</H2>
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Copyright (C) 1990 by Angus Duggan
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Copyright (C) 1989 by Jef Poskanzer.
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<P>
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted, provided
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that the above copyright notice appear in all copies and that both that
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copyright notice and this permission notice appear in supporting
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documentation. This software is provided "as is" without express or
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implied warranty.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">SEE ALSO</A><DD>
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<DT id="5"><A HREF="#lbAF">AUTHOR</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:21 GMT, March 31, 2021
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</BODY>
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</HTML>
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