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<H1>pgmabel</H1>
Updated: June 2002
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<A HREF="#index">Table Of Contents</A>
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<H2>NAME</H2>
pgmabel - create cross section using Abel Integration for Deconvolution
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<H2>SYNOPSIS</H2>
<b>pgmabel</b>
[<b>-help</b>]
[<b>-axis</b> <i>axis</i>]
[<b>-factor</b> <i>factor</i>]
[<b>-pixsize</b> <i>pixsize</i>]
[<b>-left</b> | <b>-right</b>]
[<b>-verbose</b>]
[<I>filespec</I>]
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<H2>DESCRIPTION</H2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p><b>pgmabel</b> reads as input a PGM image, which it assumes to be an
image of a rotational symmetric transparent object. The image must have
a vertical symmetry axis. <b>pgmabel</b> produces as output an image of
a cross-section of the image.
<b>pgmabel</b> does the calculation by performing the Abel Integration
for Deconvolution of an axial-symmetrical image by solving the system
of linear equations.
After integration, <b>pgmabel</b> weights all gray-values of one side
by the surface area of the calculated ring in square pixels divided by
4*<i>factor</i> multiplied by the size of one pixel (<i>pixsize</i>).
With the <b>-verbose</b> option, <b>pgmabel</b> prints the weighting
factors.
<P>Where the calculation generates a negative result, the output is black.
<P>The computation is unstable against periodic structures with size 2 in
the vertical direction.
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<H2>OPTIONS</H2>
<P>You can abbreviate any option to its shortest unique prefix.
<DL COMPACT>
<dt><b>-help</b>
<dd>Prints a help message.
<dt><b>-axis</b> <i>axis</i>
<dd>Position of the axis of symmetry in the image in pixels from the left
edge of the image. Default is the center of the image.
<dt><b>-factor</b> <i>factor</i>
<dd>User defined factor for enhancement of the output. Use a <i>factor</i>
less than 1 for decreasing gary values. Default is 1.0.
<dt><b>-pixsize</b> <i>pixsize</i>
<dd>The size of a pixel for getting scale invariant. Default is 0.1.
<dt><b>-left</b>
Calculate only the left side of the image. You cannot specify both
<b>left</b> and <b>right</b>.
<dt><b>-right</b>
Analogous to <b>-left</b>.
<dt><b>-verbose</b>
<dd>print information about the calculation.
</DL>
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<h2>EXAMPLE</h2>
<p>Rotate a PGM image to get an image with a vertical axis of symmetry,
then calculate the cross section:
<pre>
pnmrotate 90 file.pgm | pgmabel -axis 140 >cross_section.pgm
</pre>
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<H2>SEE ALSO</H2>
<B><A HREF="pnmrotate.html">pnmrotate</A></B>,
<B><A HREF="pgm.html">pgm</A></B>,
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<H2>HISTORY</H2>
<p>This program was added to Netpbm in Release 10.3 (June 2002).
<A NAME="author"></a>
<h2>AUTHOR</h2>
<p>Volker Schmidt (lefti@voyager.boerde.de)
<p>Copyright (C) 1997-2002 German Aerospace research establishment
<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">OPTIONS</A>
<LI><A HREF="#example">EXAMPLE</A>
<LI><A HREF="#lbAF">SEE ALSO</A>
<LI><A HREF="#history">HISTORY</A>
<LI><A HREF="#author">AUTHOR</A>
</UL>
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