| Re: advanced image enhancement [message #32480] |
Mon, 14 October 2002 09:23  |
David Oesch
Messages: 31
Registered: October 2000
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thany you guys...<br>
it works fine!<br>
<br>
D<br>
<br>
Liam E. Gumley wrote:<br>
<blockquote type="cite" cite="mid:3DAAF70C.1367D29F@ssec.wisc.edu">
<pre wrap="">"Liam E. Gumley" wrote:<br></pre>
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<pre wrap="">David Oesch wrote:<br></pre>
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<pre wrap="">Is there any other possibility to enhance the content of an bytarr<br>image? I tried BYTSCL and HIST_EQUAL, but ?m actually lokking for a Root<br>enhancement, also known as a logarithmic transform, which particularly<br>effective with images whose grey level distribution exhibits right<br>skewness. The root enhancement stretches the dynamic range of the low<br>end of the image while compressing its high end. It tends to lend an<br> overall brightening to the resultant image.Has anyone implemented such<br>an enhancement in IDL?<br></pre>
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<pre wrap="">Here's a simple example of a square root enhancement:<br><br>a = dist(256)<br>scale = (a - min(a)) / (max(a) - min(a))<br>tv, byte(255.0 * scale) ; linear enhancement<br>tv, byte(255.0 * sqrt(scale)) ; square root enhancement<br><br>For extra credit, turn this into a function that accepts MIN, MAX,<br>BOTTOM, and NCOLORS keywords.<br></pre>
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<pre wrap=""><!----><br>I should have check the User Libraries first:<br><br><a class="moz-txt-link-freetext" href=" http://www.astro.washington.edu/deutsch-bin/getpro/library13 .html?SQRTSCL"> http://www.astro.washington.edu/deutsch-bin/getpro/library13 .html?SQRTSCL</a><br><br>Cheers,<br>Liam.<br>Practical IDL Programming<br><a class="moz-txt-link-freetext" href="http://www.gumley.com/">http://www.gumley.com/</a><br></pre>
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<pre class="moz-signature" cols="$mailwrapcol">--
_________________________________________________
David Oesch - Remote Sensing Research Group
Department of Geography
University of Bern Tel : +41 (0)31 631 8020
Hallerstr. 12 Fax : +49 (0)89 2443 43780
CH - 3012 Bern Mail: <a class="moz-txt-link-abbreviated" href="mailto:David.Oesch@giub.unibe.ch">David.Oesch@giub.unibe.ch</a>
Switzerland <a class="moz-txt-link-freetext" href="http://www.giub.unibe.ch/remsen">http://www.giub.unibe.ch/remsen</a>
Remote Sensing is...
Staying as far away from the problem as possible.
- G. Archer, World Bank
_________________________________________________
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