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<!-- name="Oliver Rauch" -->
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<!-- subject="Re: Fix for grayscale scans with gamma &lt; 1.0" -->
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<title>sane-devel: Re: Fix for grayscale scans with gamma &lt; 1.0</title>
<h1>Re: Fix for grayscale scans with gamma &lt; 1.0</h1>
<b>Oliver Rauch</b> (<a href="mailto:oliver.rauch@Wolfsburg.DE"><i>oliver.rauch@Wolfsburg.DE</i></a>)<br>
<i>Wed, 23 Jun 1999 21:54:16 +0200</i>
<p>
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<li> <b>Next message:</b> <a href="0164.html">Nick Lamb: "Re: Fix for grayscale scans with gamma &lt; 1.0"</a>
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<li> <b>Maybe in reply to:</b> <a href="0154.html">David Fox: "Fix for grayscale scans with gamma &lt; 1.0"</a>
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<li> <b>Next in thread:</b> <a href="0167.html">David Fox: "Re: Fix for grayscale scans with gamma &lt; 1.0"</a>
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David Fox wrote:<br>
<p>
<i>&gt; Oliver Rauch &lt;<a href="mailto:oliver.rauch@Wolfsburg.DE">oliver.rauch@Wolfsburg.DE</a>&gt; writes:</i><br>
<i>&gt;</i><br>
<i>&gt; &gt; David Fox wrote:</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; &gt; Oliver Rauch &lt;<a href="mailto:oliver.rauch@Wolfsburg.DE">oliver.rauch@Wolfsburg.DE</a>&gt; writes:</i><br>
<i>&gt; &gt; &gt;</i><br>
<i>&gt; &gt; &gt; &gt; I uploaded xsane-0.26 to my homepage:</i><br>
<i>&gt; &gt; &gt; &gt; <a href="http://www.wolfsburg.de/~rauch/sane/sane-xsane.html">http://www.wolfsburg.de/~rauch/sane/sane-xsane.html</a></i><br>
<i>&gt; &gt; &gt;</i><br>
<i>&gt; &gt; &gt; Oliver,</i><br>
<i>&gt; &gt; &gt;</i><br>
<i>&gt; &gt; &gt; I've found a bug whose most obvious symptom is that grayscale scans</i><br>
<i>&gt; &gt; &gt; with a gamma &lt; 1.0 come out pure black.</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; Hi David,</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; thanks for that info,</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; I thought I corrected all this</i><br>
<i>&gt; &gt; (but looks I only tested the color routines).</i><br>
<i>&gt; &gt;</i><br>
<i>&gt; &gt; This will be ok in xsane-0.27!</i><br>
<i>&gt;</i><br>
<i>&gt; No problem... I'm currently scanning some very old and deteriorating</i><br>
<i>&gt; black and white photographs, and I've noticed a couple of problems</i><br>
<i>&gt; with using xsane. First, the range of the xsane brightness and</i><br>
<i>&gt; contrast controls is much less than the range provided in scanimage,</i><br>
<i>&gt; at least with my HP-3c scanner using the HP back-end.</i><br>
<i>&gt;</i><br>
<i>&gt; Second, I think I will also need to be able to change the brightness</i><br>
<i>&gt; and contrast settings used when acquiring the preview, and see new</i><br>
<i>&gt; histograms and perform the usual xsane modifications in relation to</i><br>
<i>&gt; those new ``default'' settings.</i><br>
<p>
The birghtness and contrast of xsane is a software created digital gamma<br>
table and has nothing to do with the options the scanner makes available,<br>
these are still available in xsane under standard or advanced options!<br>
<p>
You can change the scanner brightness and contrast and do a new preview<br>
scan and see the changes in the histogram.<br>
I think about adding support for a preview scan with more than 8/24 bits/pixel,<br>
but I am not sure if that really is necessary.<br>
<p>
<i>&gt;</i><br>
<i>&gt;</i><br>
<i>&gt; If we could make these changes (and I do plan to work on this) and add</i><br>
<i>&gt; a few tweaks like changing the cursor when the rubber band is</i><br>
<i>&gt; grabbable I think xsane could be a superior scanning client to any</i><br>
<i>&gt; I've used in the Windows world. (IMHO.)</i><br>
<i>&gt;</i><br>
<p>
This is planned, but in the moment I spent my time for the umax backend<br>
because UMAX gave me to scanners to test/make supported by the<br>
backend.<br>
<p>
May be next month I find the time to work again on xsane!<br>
<p>
Bye<br>
Oliver<br>
<p>
<p>
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--
EMAIL: <a href="mailto:Oliver.Rauch@Wolfsburg.DE">Oliver.Rauch@Wolfsburg.DE</a>
WWW: <a href="http://www.wolfsburg.de/~rauch">http://www.wolfsburg.de/~rauch</a>
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<p>
<ul>
<!-- next="start" -->
<li> <b>Next message:</b> <a href="0164.html">Nick Lamb: "Re: Fix for grayscale scans with gamma &lt; 1.0"</a>
<li> <b>Previous message:</b> <a href="0162.html">Oliver Rauch: "Re: Newbie question ;-)"</a>
<li> <b>Maybe in reply to:</b> <a href="0154.html">David Fox: "Fix for grayscale scans with gamma &lt; 1.0"</a>
<!-- nextthread="start" -->
<li> <b>Next in thread:</b> <a href="0167.html">David Fox: "Re: Fix for grayscale scans with gamma &lt; 1.0"</a>
<li> <b>Reply:</b> <a href="0167.html">David Fox: "Re: Fix for grayscale scans with gamma &lt; 1.0"</a>
<!-- reply="end" -->
</ul>