91 lines
2.1 KiB
HTML
91 lines
2.1 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 pgmedge</TITLE>
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</HEAD><BODY>
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<H1>pgmedge</H1>
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Section: User Commands (1)<BR>Updated: 04 February 1990<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="ixAAB"></A>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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pgmedge - edge-detect a portable graymap
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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>pgmedge</B>
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[<I>pgmfile</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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Reads a portable graymap as input.
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Outlines the edges, and writes a portable graymap as output.
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<A NAME="ixAAC"></A>
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Piping the result through
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<B>pgmtopbm -threshold</B>
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and playing with the
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threshold value will give a bitmap of the edges.
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<A NAME="ixAAD"></A>
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<P>
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The edge detection technique used is to take the Pythagorean sum of
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two Sobel gradient operators at 90 degrees to each other.
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For more details see "Digital Image Processing" by Gonzalez and Wintz,
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chapter 7.
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<P>
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The maxval of the output is the same as the maxval of the input The
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effect is better with larger maxvals, so you may want to increase the
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maxval of the input by running it through
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<B>pnmdepth</B>
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first.
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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+pgmenhance">pgmenhance</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?1+pnmdepth">pnmdepth</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?5+pgm">pgm</A></B>(5),
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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) 1991 by Jef Poskanzer.
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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: 00:05:22 GMT, March 31, 2021
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</BODY>
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</HTML>
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