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107 wiersze
6.3 KiB
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<!-- received="Fri Aug 29 13:55:17 1997 MST" -->
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<!-- sent="Fri, 29 Aug 1997 22:28:35 +0200" -->
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<!-- name="Rainer Krienke" -->
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<!-- email="krienke@mailhost.uni-koblenz.de" -->
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<!-- subject="Re: Backtracking in color scanning" -->
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<!-- id="9708291813.AA19446@gypsy.atlantic.infi.net" -->
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<!-- inreplyto="Backtracking in color scanning" -->
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<title>sane-devel: Re: Backtracking in color scanning</title>
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<h1>Re: Backtracking in color scanning</h1>
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<b>Rainer Krienke</b> (<a href="mailto:krienke@mailhost.uni-koblenz.de"><i>krienke@mailhost.uni-koblenz.de</i></a>)<br>
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<i>Fri, 29 Aug 1997 22:28:35 +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#105">[ date ]</a><a href="index.html#105">[ thread ]</a><a href="subject.html#105">[ subject ]</a><a href="author.html#105">[ author ]</a>
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<li> <b>Next message:</b> <a href="0106.html">Rogier Wolff: "Re: Backtracking in color scanning"</a>
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<li> <b>Previous message:</b> <a href="0104.html">shendrix@gypsy.atlantic.infi.net: "Re: Backtracking in color scanning"</a>
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<li> <b>Maybe in reply to:</b> <a href="0101.html">Rainer krienke: "Backtracking in color scanning"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0107.html">Michael Ritzert: "Re: Backtracking in color scanning"</a>
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<li> <b>Reply:</b> <a href="0107.html">Michael Ritzert: "Re: Backtracking in color scanning"</a>
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<li> <b>Reply:</b> <a href="0116.html">Wolfgang Jung: "Re: Backtracking in color scanning"</a>
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<!-- reply="end" -->
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</ul>
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<!-- body="start" -->
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David Mosberger-Tang schrieb:<br>
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<i>> </i><br>
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<i>> >>>>> On Fri, 29 Aug 1997 17:04:01 +0200, Rainer krienke <<a href="mailto:krienke@mailhost.uni-koblenz.de">krienke@mailhost.uni-koblenz.de</a>> said:</i><br>
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<i>> </i><br>
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<i>> Rainer> When I scan color images at resolutions of say 300dpi the</i><br>
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<i>> Rainer> scan process works right, but is very slow. This is because</i><br>
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<i>> Rainer> the scanner scans some line and then goes back (that's</i><br>
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<i>> Rainer> backtracking if I understood it right) and then scans the</i><br>
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<i>> Rainer> next lines. Looking at the scanner it seems the the way the</i><br>
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<i>> Rainer> scanner goes back is just a little smaller then the way it</i><br>
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<i>> Rainer> has scanned before. Scanning a paper of size DINA4 (~30cm at</i><br>
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<i>> Rainer> length, ~21cm wide) at 300dpi takes about 2min and 45</i><br>
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<i>> Rainer> sec. If I scan at 100 dpi the effect is basically still</i><br>
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<i>> Rainer> there but the sanner then scans a larger area in one step</i><br>
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<i>> Rainer> before going back only a little. So the whole thing works</i><br>
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<i>> Rainer> faster.</i><br>
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<i>> </i><br>
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<i>> Rainer> What suprises me a lot, is that under windows doing the same</i><br>
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<i>> Rainer> scanprocess at the same resolution (via the mustec-twain</i><br>
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<i>> Rainer> driver) does not cause backtracking to occur and is</i><br>
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<i>> Rainer> completed much much faster (not even half the time).</i><br>
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<i>> </i><br>
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<i>> What size scan-buffer are you using? If you're using the default size</i><br>
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<i>> of 32KB, could you try increasing it to 127.5KB? See sane-scsi(5) for</i><br>
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<i>> info on how to do that.</i><br>
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<i>> </i><br>
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<i>> If increasing the scan buffer size to 127.5KB doesn't help, the</i><br>
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<i>> backtracking could be due to timing problems. If the scanner software</i><br>
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<i>> is too slow to issue the next "read data" command then backtracking</i><br>
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<i>> would occur. What kind of computer are you using and how much memory</i><br>
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<i>> does it have?</i><br>
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<i>> </i><br>
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<i>> --david</i><br>
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<i>> </i><br>
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<p>
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As I already told in my mail. The scanbuffer is 127K large (in Kernel<br>
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and sane).Scanning works allrightfor me (the results are allright but<br>
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not the scantime). My computer is a 90Mhz Pentium it has 48Mb RAM<br>
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installed. So it cannot be the buttleneck. But I really think it's got<br>
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to do with data xfer since it does not happen when scanning at a lower<br>
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resolution or in Lineart mode where less data has to be xferred. <br>
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<p>
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Could it be that its because the scanner and the harddisk on which the<br>
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data has to be stored is on the same controller (ADAPTEC 2940) like the<br>
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scanner so that there is a problem. <br>
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<p>
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By the way I really do not understand why backtracking is needed after<br>
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all, cause I don't know whats really happening. Can someone give me a<br>
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pointer to information on this ?<br>
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<p>
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I think I did not say this but it should be said: Sane is a real great<br>
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piece of software besides all problems that there are (naturally), or<br>
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has anyone seen a windows release without bugs ....<br>
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<p>
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Rainer <br>
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<p>
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----------------------------------------------------------------------<br>
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Rainer Krienke <a href="mailto:krienke@informatik.uni-koblenz.de">krienke@informatik.uni-koblenz.de</a><br>
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Universitaet Koblenz, <a href="http://www.uni-koblenz.de/~krienke">http://www.uni-koblenz.de/~krienke</a><br>
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Rechenzentrum, Voice: +49 261 9119-641<br>
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Rheinau 3-4, 56075 Koblenz, Germany Fax: +49 261 9119-499<br>
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----------------------------------------------------------------------<br>
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<p>
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<pre>
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--
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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="0106.html">Rogier Wolff: "Re: Backtracking in color scanning"</a>
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<li> <b>Previous message:</b> <a href="0104.html">shendrix@gypsy.atlantic.infi.net: "Re: Backtracking in color scanning"</a>
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<li> <b>Maybe in reply to:</b> <a href="0101.html">Rainer krienke: "Backtracking in color scanning"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0107.html">Michael Ritzert: "Re: Backtracking in color scanning"</a>
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<li> <b>Reply:</b> <a href="0107.html">Michael Ritzert: "Re: Backtracking in color scanning"</a>
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<li> <b>Reply:</b> <a href="0116.html">Wolfgang Jung: "Re: Backtracking in color scanning"</a>
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<!-- reply="end" -->
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</ul>
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