86 lines
3.2 KiB
HTML
86 lines
3.2 KiB
HTML
<html>
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<title>USM Renderer</title>
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<style type="text/css">
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TABLE.ba { max-width: 678; text-align: center; padding-bottom: 15; padding-top: 5}
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TABLE.inline { padding-right: 300; clear: left}
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TD.text_table {padding-left: 2; padding-right: 2; border-width: 1}
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H2 {clear: left}
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P {max-width: none; padding-right: 300; clear: left}
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BLOCKQUOTE {padding-right: 400 }
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LI {max-width: 640; clear: left}
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P.footer {max-width: none; width: auto; padding-left: 0}
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P.header {max-width: none; width: auto; padding-left: 0}
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HR.main {max-width: 640; clear: left; padding-left: 0; margin-left: 0}
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HR.footer {clear: both}
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</style>
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</head><body>
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<table align=right valign=top width=160>
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<td valign=top height=600 width=160>
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<a href="http://auricle.dyndns.org/ALE/">
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<big>ALE</big>
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<br>
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Image Processing Software
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<br>
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<br>
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<small>Deblurring, Anti-aliasing, and Superresolution.</small></a>
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<br><br>
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<big>
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Local Operation
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</big>
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<hr>
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localhost<br>
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5393119533<br>
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</table>
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<p><b>[ <a href="../">Up</a> <!-- | <a href="../../ba/big_about.html">Examples</a> --> ]</b></p>
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<h1>USM Renderer</h1>
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<p>The Unsharp Mask Renderer is a built-in post-processing step based on the
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unsharp mask technique, which has been used to enhance high frequencies since
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the days of photographic plate processing (see, for example, <a
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href="http://www.scenic-route.com/tutorial/psp/tutor/unsharp/Unsharp.htm">this
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page</a>). This renderer acts after all other rendering steps have completed,
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except for Irani-Peleg rendering, which occurs afterward.
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<h2>Properties</h2>
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<p>Given a sequence of images that satisfy all predicates for merging (or
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drizzling) except point sampling; given a known linear PSF; and given only
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translations between frames, the result of merging (or drizzling) will be an
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acceptable approximation of <b>T</b> convolved with the PSF. This does not
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imply that deconvolution of this result will be an acceptable approximation of
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<b>T</b>, however, since frequencies with low response may be reconstructed
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with poor fidelity due to reduced precision. We use the low-response
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approximation to ignore these frequencies. Assuming the USM approximation, the
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remaining frequencies are reconstructed to form an acceptable approximation of
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<b>T</b>. (Since this doesn't really constitute a proof, the results should be
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considered unreliable.)
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<p>
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<small>
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<!--
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<sup>1</sup>Ernst Lippe. refocus: A Gimp plug-in for sharpening images. <a href="http://refocus.sourceforge.net/doc.html">http://refocus.sourceforge.net/doc.html</a><br>
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<sup>2</sup>E.g. this approach was used in:
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<br>Michal Irani and Shmuel Peleg. "Improving Resolution by Image Registration". <i>Graphical
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Models and Image Processing.</i> Academic Press, May 1991. <a href="http://www.wisdom.weizmann.ac.il/~irani/abstracts/superResolution.html">http://www.wisdom.weizmann.ac.il/~irani/abstracts/superResolution.html</a> -->
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</small>
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<!--
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<h2>Examples</h2>
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<p><a href="../../ba/big_about.html">Examples</a> of post-enhancement are available.
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-->
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<hr>
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<i>Copyright 2002, 2003, 2004 <a href="mailto:dhilvert@auricle.dyndns.org">David Hilvert</a></i>
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<p>Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.
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</body>
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</html>
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