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82 wiersze
4.5 KiB
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<!-- received="Wed Jun 23 14:25:44 1999 PDT" -->
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<!-- sent="23 Jun 1999 14:26:49 -0700" -->
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<!-- name="David Fox" -->
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<!-- email="dsfox@cogsci.ucsd.edu" -->
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<!-- subject="Re: Fix for grayscale scans with gamma < 1.0" -->
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<!-- inreplyto="Wed, 23 Jun 1999 21:54:16 +0200"" -->
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<title>sane-devel: Re: Fix for grayscale scans with gamma < 1.0</title>
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<h1>Re: Fix for grayscale scans with gamma < 1.0</h1>
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<b>David Fox</b> (<a href="mailto:dsfox@cogsci.ucsd.edu"><i>dsfox@cogsci.ucsd.edu</i></a>)<br>
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<i>23 Jun 1999 14:26:49 -0700</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#167">[ date ]</a><a href="index.html#167">[ thread ]</a><a href="subject.html#167">[ subject ]</a><a href="author.html#167">[ author ]</a>
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<li> <b>Next message:</b> <a href="0168.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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<li> <b>Previous message:</b> <a href="0166.html">amalmin@coho.halcyon.com: "Re: Newbie question ;-)"</a>
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<li> <b>In reply to:</b> <a href="0163.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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<li> <b>Next in thread:</b> <a href="0168.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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</ul>
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Oliver Rauch <<a href="mailto:oliver.rauch@Wolfsburg.DE">oliver.rauch@Wolfsburg.DE</a>> writes:<br>
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<p>
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<i>> David Fox wrote:</i><br>
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<i>></i><br>
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<i>> > No problem... I'm currently scanning some very old and deteriorating</i><br>
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<i>> > black and white photographs, and I've noticed a couple of problems</i><br>
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<i>> > with using xsane. First, the range of the xsane brightness and</i><br>
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<i>> > contrast controls is much less than the range provided in scanimage,</i><br>
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<i>> > at least with my HP-3c scanner using the HP back-end.</i><br>
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<i>> ></i><br>
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<i>> > Second, I think I will also need to be able to change the brightness</i><br>
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<i>> > and contrast settings used when acquiring the preview, and see new</i><br>
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<i>> > histograms and perform the usual xsane modifications in relation to</i><br>
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<i>> > those new ``default'' settings.</i><br>
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<i>> </i><br>
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<i>> The birghtness and contrast of xsane is a software created digital gamma</i><br>
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<i>> table and has nothing to do with the options the scanner makes available,</i><br>
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<i>> these are still available in xsane under standard or advanced options!</i><br>
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<i>> </i><br>
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<i>> You can change the scanner brightness and contrast and do a new preview</i><br>
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<i>> scan and see the changes in the histogram.</i><br>
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<i>> I think about adding support for a preview scan with more than 8/24 bits/pixel,</i><br>
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<i>> but I am not sure if that really is necessary.</i><br>
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<p>
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Oh, I see, I didn't understand the significance of the standard and<br>
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advanced options. I think there might be a way to integrate all of<br>
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these controls into a unified whole. The use of the hardware's<br>
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brightness and contrast to achieve a particular goal is preferable to<br>
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the use of post processing. It would also be nice to get immediate<br>
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feedback of the effect of changing the ``standard'' brightness and<br>
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contrast controls, the way you do with the xsane controls. I suppose<br>
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that you could do a some calibration, sampling an image at various<br>
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settings and construct a function representing the scanner's response<br>
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curve?<br>
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<p>
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Maybe when you stop manipulating the controls it could actually go out<br>
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and get a new preview without being asked?<br>
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<pre>
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--
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David Fox <a href="http://hci.ucsd.edu/dsf">http://hci.ucsd.edu/dsf</a> xoF divaD
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UCSD HCI Lab baL ICH DSCU
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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="0168.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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<li> <b>Previous message:</b> <a href="0166.html">amalmin@coho.halcyon.com: "Re: Newbie question ;-)"</a>
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<li> <b>In reply to:</b> <a href="0163.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0168.html">Oliver Rauch: "Re: Fix for grayscale scans with gamma < 1.0"</a>
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<!-- reply="end" -->
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</ul>
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