sane-project-website/old-archive/1998-08/0015.html

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<!-- name="Matto Marjanovic" -->
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<title>sane-devel: Re: level adjustment widget in xscanimage?</title>
<h1>Re: level adjustment widget in xscanimage?</h1>
<b>Matto Marjanovic</b> (<a href="mailto:maddog@mir.com"><i>maddog@mir.com</i></a>)<br>
<i>Wed, 5 Aug 1998 11:03:56 -0400 (EDT)</i>
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<i> &gt;From: Steffen Renisch &lt;<a href="mailto:steffen@thutmosis.rz-berlin.mpg.de">steffen@thutmosis.rz-berlin.mpg.de</a>&gt;</i><br>
<i> &gt;Date: Wed, 5 Aug 1998 12:57:58 +0200 (CEST)</i><br>
<p>
<i> &gt;I wonder if wouldn't be useful to incorporate some 'level adjustment</i><br>
<i> &gt;widget' under xscanimage, as a complement to the custom gamma correction.</i><br>
...<br>
<i> &gt;19 and 231 to 255. Doing this while scanning should have the adavantage</i><br>
<i> &gt;that at least some (if not all) scanners have the ability to adjust</i><br>
<i> &gt;their absolute white and black level, so that you get always the full</i><br>
<i> &gt;range of 256 intensity shades, whereas if you adjust levels afterwards,</i><br>
<i> &gt;you lose always some shades, which sometimes makes a visible difference.</i><br>
<p>
For what scanners?  The microtek backend already provides such<br>
 controls (and the sliders appear in xscanimage), since the<br>
 black/white levels are controllable on microtek scanners.<br>
<p>
<i> &gt;Such widget should even look very much the same as the level adjustment</i><br>
<i> &gt;widget under the gimp, i.e. you should see a histogram of the current</i><br>
<i> &gt;scan region (possibly evaluated by the preview) and you should be able</i><br>
<i> &gt;to set you new black and white levels (and perhaps the 'gamma point')</i><br>
<i> &gt;from the histogram; then the scanner gets recalibrated to the new </i><br>
<i> &gt;black and white points, and voila, you new scan is done with the new tonal</i><br>
<i> &gt;range.</i><br>
<p>
It's hard, I think, to incorporate the controls into the histogram, <br>
 because you don't necessarily know the true transfer function hidden<br>
 within the scanner (and thus can't really update the histogram without<br>
 doing another scan), but a histogram window alone is a neat idea.<br>
<p>
-matt m.<br>
<p>
<pre>
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<li> <b>Next message:</b> <a href="0016.html">Yuri Dario: "Re: SANEI_THREAD proposal"</a>
<li> <b>Previous message:</b> <a href="0014.html">Brian Schau: "SV: i wanna outta here"</a>
<li> <b>Maybe in reply to:</b> <a href="0013.html">Steffen Renisch: "level adjustment widget in xscanimage?"</a>
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<li> <b>Next in thread:</b> <a href="0017.html">Oliver Rauch: "Re: level adjustment widget in xscanimage?"</a>
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