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79 wiersze
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<!-- received="Thu Dec 3 09:13:05 1998 PST" -->
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<!-- sent="Thu, 3 Dec 1998 12:05:08 -0500 (EST)" -->
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<!-- name="William L. Sebok" -->
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<!-- email="wls@astro.umd.edu" -->
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<!-- subject="Re: Adjusting contrast and brightness" -->
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<!-- id="199812031705.MAA19619@earth.astro.umd.edu" -->
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<!-- inreplyto="Adjusting contrast and brightness" -->
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<title>sane-devel: Re: Adjusting contrast and brightness</title>
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<h1>Re: Adjusting contrast and brightness</h1>
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<b>William L. Sebok</b> (<a href="mailto:wls@astro.umd.edu"><i>wls@astro.umd.edu</i></a>)<br>
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<i>Thu, 3 Dec 1998 12:05:08 -0500 (EST)</i>
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<p>
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<ul>
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<li> <b>Messages sorted by:</b> <a href="date.html#23">[ date ]</a><a href="index.html#23">[ thread ]</a><a href="subject.html#23">[ subject ]</a><a href="author.html#23">[ author ]</a>
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<li> <b>Next message:</b> <a href="0024.html">David Fox: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Previous message:</b> <a href="0022.html">David Fox: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Maybe in reply to:</b> <a href="0004.html">David Fox: "Adjusting contrast and brightness"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0035.html">Matthias Fleischer: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Next in thread:</b> <a href="0008.html">Jon Knight: "Re: Genius scanners"</a>
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<!-- reply="end" -->
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</ul>
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<!-- body="start" -->
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I said:<br>
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<i>> Actually, automatically choosing brightness, contrast and gamma from</i><br>
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<i>> a selection on the preview is exactly the feature on the windows</i><br>
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<i>> driver for my Umax S12 that I miss most in sane. That and being</i><br>
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<i>> able to zoom the preview window to make a decently precise</i><br>
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<i>> selection.</i><br>
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<p>
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David Fox:<br>
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<i>> Having the software actually select the contrast and brightness and</i><br>
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<i>> gamma is a lot trickier, with subjective elements. Its one of those</i><br>
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<i>> problems, like the travelling salesman problem, that are impossible in</i><br>
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<i>> theory but solved in practice every day. Are the algorithms for doing</i><br>
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<i>> this proprietary, or are there no image processing experts here? I</i><br>
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<i>> know about image synthesis, but not much about image processing.</i><br>
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<p>
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One of the things the Umax S12 software sets automatically is the dark and<br>
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brightest pixels. This is fairly easy to measure and is usually what I want<br>
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to do anyway (of course how it maps into the backend controls is another<br>
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matter). It does indeed show the effect of the adjustments on the preview<br>
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without rescanning. However I don't really think it gets it right, showing<br>
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the preview as lighter than the the scanned image looks. I suspect the problem<br>
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is a disagreement with photoshop and the gimp over monitor gamma.<br>
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<p>
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Oliver Rauch <<a href="mailto:oliver.rauch@Wolfsburg.DE">oliver.rauch@Wolfsburg.DE</a>> said:<br>
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<i>> Will all be included into my new frontend.</i><br>
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<i>> Online gamma/contrast/brightness-changes already work,</i><br>
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<i>> automatic contrast/brightness is easy to implement.</i><br>
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<p>
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<i>> I think I will make a pre-alpha-version available next week!</i><br>
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<p>
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Great! Is zooming of the preview window present in this alpha version?<br>
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I would love to alpha test it as lack of these features has kept me preferring<br>
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to keep using the windows software.<br>
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<p>
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Bill Sebok Computer Software Manager, Univ. of Maryland, Astronomy<br>
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Internet: <a href="mailto:wls@astro.umd.edu">wls@astro.umd.edu</a> URL: <a href="http://www.astro.umd.edu/~wls/">http://www.astro.umd.edu/~wls/</a><br>
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<p>
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<pre>
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--
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Source code, list archive, and docs: <a href="http://www.mostang.com/sane/">http://www.mostang.com/sane/</a>
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To unsubscribe: echo unsubscribe sane-devel | mail <a href="mailto:majordomo@mostang.com">majordomo@mostang.com</a>
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</pre>
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<!-- body="end" -->
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<p>
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<ul>
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<!-- next="start" -->
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<li> <b>Next message:</b> <a href="0024.html">David Fox: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Previous message:</b> <a href="0022.html">David Fox: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Maybe in reply to:</b> <a href="0004.html">David Fox: "Adjusting contrast and brightness"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0035.html">Matthias Fleischer: "Re: Adjusting contrast and brightness"</a>
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<li> <b>Next in thread:</b> <a href="0008.html">Jon Knight: "Re: Genius scanners"</a>
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<!-- reply="end" -->
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</ul>
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