123 lines
2.3 KiB
HTML
123 lines
2.3 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 pgmkernel</TITLE>
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</HEAD><BODY>
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<H1>pgmkernel</H1>
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Section: User Commands (1)<BR>Updated: 10 December 1992<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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pgmkernel - generate a convolution kernel
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>pgmkernel</B>
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[
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<B>-weight</B>
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<I>w</I>
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]
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<I>width </I>
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[
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<I>height </I>
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]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Generates a portable graymap array of size
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<I>width </I>
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x
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<I>height </I>
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(or
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<I>width </I>
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x
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<I>width </I>
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if
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<I>height </I>
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is not specified) to be used as a convolution file by
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<B>pnmconvol</B>.
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The data in the convolution array K are computed according to the
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formula:
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<P>
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K(i,j) = 1 / ( 1 + w * sqrt((i-width/2)^2 + (j-height/2)^2))
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<P>
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where
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<I>w </I>
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is a coefficient specified via the
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<I>-weight </I>
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flag, and
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<I>width </I>
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and
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<I>height</I>
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are the X and Y filter sizes.
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<P>
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The output PGM file is always written out in ASCII format.
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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The optional
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<I>-weight </I>
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flag should be a real number greater than -1.
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The default value is 6.0.
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<A NAME="lbAF"> </A>
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<H2>BUGS</H2>
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The computation time is proportional to
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<I>width </I>
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*
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<I>height</I>.
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This increases rapidly with the increase of the kernel size.
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A better approach could be using a FFT in these cases.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<A HREF="/cgi-bin/man/man2html?1+pnmconvol">pnmconvol</A>(1), <A HREF="/cgi-bin/man/man2html?1+pnmsmooth">pnmsmooth</A>(1)
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<A NAME="lbAH"> </A>
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<H2>AUTHOR</H2>
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Alberto Accomazzi (<A HREF="mailto:alberto@cfa.harvard.edu">alberto@cfa.harvard.edu</A>).
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<P>
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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">OPTIONS</A><DD>
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<DT id="5"><A HREF="#lbAF">BUGS</A><DD>
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<DT id="6"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="7"><A HREF="#lbAH">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: 00:05:23 GMT, March 31, 2021
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