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106 wiersze
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<!-- received="Thu Nov 19 15:39:26 1998 PST" -->
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<!-- sent="Fri, 20 Nov 1998 00:31:31 +0100" -->
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<!-- name="Bernd Schroeder" -->
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<!-- email="bernd@aquila.muc.de" -->
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<!-- subject="Re: Patch for Microtek ScanMaker X6 (microtek2 backend)" -->
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<!-- inreplyto="199811191453.PAA07046@elephant.cs.tu-berlin.de" -->
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<title>sane-devel: Re: Patch for Microtek ScanMaker X6 (microtek2 backend)</title>
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<h1>Re: Patch for Microtek ScanMaker X6 (microtek2 backend)</h1>
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<b>Bernd Schroeder</b> (<a href="mailto:bernd@aquila.muc.de"><i>bernd@aquila.muc.de</i></a>)<br>
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<i>Fri, 20 Nov 1998 00:31:31 +0100</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#172">[ date ]</a><a href="index.html#172">[ thread ]</a><a href="subject.html#172">[ subject ]</a><a href="author.html#172">[ author ]</a>
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<li> <b>Next message:</b> <a href="0173.html">Jonathan Buzzard: "Re: News from Minolta"</a>
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<li> <b>Previous message:</b> <a href="0171.html">Bernd Schroeder: "Re: Microtek scanner V600"</a>
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<li> <b>In reply to:</b> <a href="0162.html">Sebastian Erdmann: "Patch for Microtek ScanMaker X6 (microtek2 backend)"</a>
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</ul>
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Hi,<br>
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<p>
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On Thu, Nov 19, 1998 at 03:53:49PM +0100, Sebastian Erdmann wrote:<br>
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<i>> </i><br>
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<i>> Hi,</i><br>
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<i>> </i><br>
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<i>> my Microtek Scanmaker X6 exhibits some strange behavior: After</i><br>
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<i>> switching it on, colors (or greyscale tones) are "washed out" and</i><br>
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<i>> horizontally unbalanced across the image. This occurs when using</i><br>
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<i>> SANE 0.74 as well as SANE pre1.00. A simple workaround is to</i><br>
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<i>> power-cycle the scanner (while keeping the computer running).</i><br>
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<p>
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This sounds indeed strange. Normally the scanner should be in reset state <br>
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after it is switched on. Or are the colors wrong if the scanner is switched<br>
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on before the system is booted (or the SCSI driver is loaded) ? Then<br>
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the SCSI driver sends one or more commands to the device, but these<br>
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commands should not affect the results of a scan.<br>
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<p>
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<i>> But since the windoze twain drivers can get the scanner to work</i><br>
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<i>> without that extra power-cycle, I wasn't satisfied with the</i><br>
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<i>> situation and started to look for a better solution. Unfortunately,</i><br>
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<i>> the trace information obtained from setting "option dump 4" in</i><br>
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<i>> microtek2.conf and setting SANE_DEBUG_MICROTEK2=255 in the</i><br>
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<i>> environment didn't show significant differences between the</i><br>
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<i>> "colors washed out" case and the normal case. In fact, the only</i><br>
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<i>> difference I found turned out to be unrelated to the problem, but</i><br>
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<i>> I fixed it anyway to prevent potential problems: The scanner seems</i><br>
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<i>> to come up with random values for the NTRACK and NCALIB bits in</i><br>
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<i>> the system status. The fix (included in the patch below) was to</i><br>
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<i>> explicitly set these bits to zero in sane_start().</i><br>
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<p>
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NCALIB set to 1 prevents the scanner from calibration before a scan.<br>
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This is explicitly set (and later reset) in the do_dummy_scan()-function.<br>
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Please check, whether the differences for this bit result from these<br>
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different settings.<br>
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<p>
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The NTRACK bit, however, should always be 0 in this version of the backend.<br>
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In the next release there will be an option to set this bit explicitly<br>
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(and thus avoiding backtracking).<br>
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<p>
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<i>> But the "colors washed out" problem did still persist.</i><br>
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<i>> However, after some experimentation I found out that issuing</i><br>
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<i>> a SEND DIAGNOSTIC command (which performs a scanner self test)</i><br>
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<i>> fixes the problem. Since this command keeps the scanner busy for</i><br>
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<i>> quite some time, I added a flag to the Microtek2_Device struct</i><br>
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<i>> so the self test is only performed once in a xscanimage session.</i><br>
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<p>
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I experimented with this command myself a while ago as a replacement for<br>
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this "do_dummy_scan" stuff, but it has some disadvantages.<br>
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<p>
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In particular this command is used for every scan if scanimage is used, and<br>
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as you wrote the execution of this command takes some time. On my<br>
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own ScanMaker 630 every second "send diagnostics" fails, BTW, with<br>
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sense code "lamp failure" :/ .<br>
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<p>
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I suggest not to include this patch into sane-1.00, but to remove the<br>
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NTRACK and NCALIB changes, and also to introduce an option in the<br>
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configuration file to enable/disable the "send diagnostics" command<br>
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(but in a later release of the backend).<br>
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<p>
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Bernd<br>
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<p>
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<pre>
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--
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Bernd Schroeder
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Email: <a href="mailto:bernd@aquila.muc.de">mailto:bernd@aquila.muc.de</a>
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PGP public key available: <a href="mailto:pgp@aquila.muc.de">mailto:pgp@aquila.muc.de</a> | Subject: send key
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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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</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="0173.html">Jonathan Buzzard: "Re: News from Minolta"</a>
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<li> <b>Previous message:</b> <a href="0171.html">Bernd Schroeder: "Re: Microtek scanner V600"</a>
|
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<li> <b>In reply to:</b> <a href="0162.html">Sebastian Erdmann: "Patch for Microtek ScanMaker X6 (microtek2 backend)"</a>
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<!-- nextthread="start" -->
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</ul>
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