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128 wiersze
5.7 KiB
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<!-- received="Fri Jul 16 06:44:48 1999 PDT" -->
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<!-- sent="Fri, 16 Jul 1999 15:44:56 +0200" -->
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<!-- name="Oliver Rauch" -->
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<!-- email="oliver.rauch@Wolfsburg.DE" -->
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<!-- subject="Re: Xsane questions and wish list" -->
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<!-- inreplyto="Xsane questions and wish list" -->
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<title>sane-devel: Re: Xsane questions and wish list</title>
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<h1>Re: Xsane questions and wish list</h1>
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<b>Oliver Rauch</b> (<a href="mailto:oliver.rauch@Wolfsburg.DE"><i>oliver.rauch@Wolfsburg.DE</i></a>)<br>
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<i>Fri, 16 Jul 1999 15:44:56 +0200</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#92">[ date ]</a><a href="index.html#92">[ thread ]</a><a href="subject.html#92">[ subject ]</a><a href="author.html#92">[ author ]</a>
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<!-- next="start" -->
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<li> <b>Next message:</b> <a href="0093.html">Lany Wilson: "Leoscan 3S/ Across 3S scanners"</a>
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<li> <b>Previous message:</b> <a href="0091.html">Oliver Rauch: "Re: (nil) entry in rcfiles"</a>
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<li> <b>Maybe in reply to:</b> <a href="0077.html">Steve Gunnell: "Xsane questions and wish list"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0102.html">Peter Kirchgessner: "Re: Xsane questions and wish list"</a>
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<!-- reply="end" -->
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</ul>
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<!-- body="start" -->
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Steve Gunnell wrote:<br>
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<p>
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<i>> Oliver Rauch wrote:</i><br>
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<i>></i><br>
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<i>> > xsane uses the gamma bit depth the backend uses,</i><br>
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<i>> > but the scanner gamma table has to be activated (normally</i><br>
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<i>> > by custom gamma table in standard options, but backend dependent)!</i><br>
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<i>></i><br>
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<i>> I'm just using the default settings. I assumed the scanner was beingchanged</i><br>
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<i>> because when I closed xsane and went back to xscanimage</i><br>
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<i>> my attempts to correct the white level in xsane were still being applied</i><br>
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<i>> to the xscanimage previews. I had to turn the scanner off to clear them.</i><br>
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<i>></i><br>
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<p>
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That sould not happen, may be there is a bug in the backend!<br>
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<p>
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<i>> > For what do you need the values? In the histogram window</i><br>
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<i>></i><br>
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<i>> > you have the silders and the color density is given in the</i><br>
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<i>> > histogram window.</i><br>
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<i>></i><br>
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<i>> I'm scanning negatives. So I need to remove the colour mask from the</i><br>
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<i>> images.To do that I need to set the white point to the value of the colour</i><br>
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<i>> mask. So what</i><br>
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<i>> I do is select a scanned chunk of colour mask and average it using the gimp</i><br>
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<i>> generic convolution tool to give me the average RGB value for the colour</i><br>
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<i>> mask.</i><br>
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<i>> If I had a editable value box I could enter these values as the white point</i><br>
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<i>> just like</i><br>
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<i>> I do with the gimp histogram tool rather than having to mess around with</i><br>
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<i>> little</i><br>
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<i>> sliders that I can't control accurately. If I could set the colour mask</i><br>
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<i>> scaling and</i><br>
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<i>> the negative colour inversion once per film in xsane then I can save two</i><br>
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<i>> gimp</i><br>
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<i>> operations per frame which would be a considerable saving over the 45</i><br>
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<i>> minutes per strip of 4 negatives that the process takes now.</i><br>
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<i>></i><br>
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<i>> > If you want to use values take the brightness, contrast and gamma</i><br>
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<i>> > values!</i><br>
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<i>></i><br>
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<i>> These are no use to me because they are arbitrary values that do not</i><br>
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<i>> simplyrelate to the RGB values that I need to change.</i><br>
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<i>></i><br>
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<p>
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The highlitght and shadow values are also not the same, they depend on the<br>
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bit depth (8bit =256, 10 bit=1024 and so on).<br>
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<p>
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The contrast and brightness are well defined:<br>
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-100% brightness moves all values in 8 bit by -128<br>
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-100% contrast makes all colors to one value,<br>
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+100% contrast doubles the range of used values<br>
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<p>
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Xsane and the gimp should use the same contrast, brightness and gamma values<br>
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for the same conversion!<br>
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<p>
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<p>
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<i>></i><br>
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<i>> If you have a better method for processing negatives that takes advantage of</i><br>
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<i>></i><br>
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<i>> xsane's features then I would love to know about it.</i><br>
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<i>></i><br>
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<p>
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I disable rgb default, activate negative option and do a preview scan,<br>
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then I disable all but one color in the histogram window and set the<br>
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highlight and shadow sliders to the used range, this is done for<br>
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red, green and blue. Then I set all gamma values to 1.0<br>
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<p>
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Write down the 4 values for brightness and contrast, they are a good<br>
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start for the film (agfa, fuji,...)<br>
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<p>
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In future it is planned to save different settings, then you can save a<br>
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correction for Agfa negatives, one for Fuji and so on.<br>
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<p>
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To get real good results, you afterwards have to do a calibration by<br>
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hand, but that is the same as scanning positives!<br>
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<p>
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Bye<br>
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Oliver<br>
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<p>
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<pre>
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--
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EMAIL: <a href="mailto:Oliver.Rauch@Wolfsburg.DE">Oliver.Rauch@Wolfsburg.DE</a>
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WWW: <a href="http://www.wolfsburg.de/~rauch">http://www.wolfsburg.de/~rauch</a>
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<p>
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<p>
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<p>
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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="0093.html">Lany Wilson: "Leoscan 3S/ Across 3S scanners"</a>
|
||
<li> <b>Previous message:</b> <a href="0091.html">Oliver Rauch: "Re: (nil) entry in rcfiles"</a>
|
||
<li> <b>Maybe in reply to:</b> <a href="0077.html">Steve Gunnell: "Xsane questions and wish list"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0102.html">Peter Kirchgessner: "Re: Xsane questions and wish list"</a>
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<!-- reply="end" -->
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</ul>
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