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<!-- received="Wed Sep 9 03:56:19 1998 PDT" -->
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<!-- sent="Wed, 09 Sep 1998 13:59:00 +0300" -->
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<!-- name="Milon Firikis" -->
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<!-- email="milonf@ariadne-t.gr" -->
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<!-- subject="Re: Apple OneScanner/Color OneScanner status?" -->
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<!-- inreplyto="Apple OneScanner/Color OneScanner status?" -->
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<title>sane-devel: Re: Apple OneScanner/Color OneScanner status?</title>
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<h1>Re: Apple OneScanner/Color OneScanner status?</h1>
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<b>Milon Firikis</b> (<a href="mailto:milonf@ariadne-t.gr"><i>milonf@ariadne-t.gr</i></a>)<br>
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<i>Wed, 09 Sep 1998 13:59:00 +0300</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#61">[ date ]</a><a href="index.html#61">[ thread ]</a><a href="subject.html#61">[ subject ]</a><a href="author.html#61">[ author ]</a>
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<li> <b>Next message:</b> <a href="0062.html">Kjetil Torgrim Homme: "What works best?"</a>
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<li> <b>Previous message:</b> <a href="0060.html">Bernd Schroeder: "Re: ADF for microtek2 backend"</a>
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<li> <b>Maybe in reply to:</b> <a href="0023.html">Ian R. Justman: "Apple OneScanner/Color OneScanner status?"</a>
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</ul>
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Ian R. Justman wrote:<br>
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<i>> </i><br>
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<i>> </i><br>
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<i>> I have the Color OneScanner.</i><br>
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<i>> </i><br>
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<i>> > 2) How big is the internal buffer? (AppleScanner has 256 bytes)</i><br>
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<i>> </i><br>
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<i>> I do not know. I just assumed that much of the stuff that applies to the</i><br>
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<i>> OneScanner also applies to the Color OneScanner. all of it does, but the</i><br>
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<i>> Color OneScanner has... well... color. :)</i><br>
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<p>
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I asked this because I have a premature theory about the bug you found.<br>
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<p>
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<i>> </i><br>
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<i>> > 4) After you patch: Does everything works as expected? In all modes?</i><br>
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<i>> </i><br>
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<i>> I tested it fully in the normal OneScanner modes. Color, as your notes</i><br>
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<i>> say, needs MUCH work.</i><br>
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<p>
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The primary reason for this is the quantization stuff that I don't<br>
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really understand and it is poorly documented for scanners other the one<br>
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you have and you must do a lot of experiments to figure out how the<br>
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scanners do the quantization. Secondary reasons are the Color Correction<br>
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tables, and the Gamma vectors.<br>
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<p>
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<i>> </i><br>
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<i>> > 5) If (4==TRUE) what about the round offs in scan area that are imposed</i><br>
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<i>> > by the specific model you have. Note that in case of an unexpected round</i><br>
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<i>> > offs the SANE may wait bigger/smaller image and that may lead to</i><br>
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<i>> > undesired warnings and cropped images.</i><br>
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<i>> </i><br>
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<i>> No warnings, no cropped images, but the quantization algorithms introduce</i><br>
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<i>> some really neat effects when there are rounding problems. One mode I</i><br>
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<i>> tried does work right, but it yields a negative image. Otherwise, other</i><br>
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<i>> modes look like a horizontally-rolling picture on a TV set.</i><br>
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<p>
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Hm... I think Apple changed the polarity somewhere... I think I have an<br>
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option built-in. I don't remember if it is OneScanner or ColorOneScanner<br>
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specific. (Data Polarity?)<br>
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<br>
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<i>> If you'd like, I'll mail you sample scans and debugging loggage off-list</i><br>
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<i>> for your perusal.</i><br>
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<p>
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Yes it would be nice...<br>
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<br>
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<i> > Your patch looks that fixes a situation at the end of a scan.</i><br>
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Although<br>
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<i>> > this is fine with me, the problems I had so far (other users actually</i><br>
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<i>> > had them) was that the scanner wasn't starting the scan at all.</i><br>
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<i>> </i><br>
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<i>> Yes, my situation was that it reached the end of the scan, but there was</i><br>
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<i>> still data available, causing the scanner to remain busy because of the</i><br>
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<i>> logic problems in the status-checking code. The issue here was that the</i><br>
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<i>> scanner was presenting status that it was no longer blocked but data was</i><br>
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<i>> available. The code was transferring data ONLY when the scanner was</i><br>
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<i>> blocked, and at the end of the scan, not only was data still available,</i><br>
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<i>> the scanner was no longer in a blocked state, so said the block status</i><br>
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<i>> bit. Since the only test was on the blocking bit, the code was in a tight</i><br>
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<i>> loop waiting for that bit to be asserted, requiring me to CTRL-C out of</i><br>
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<i>> the frontend and powercycle the scanner.</i><br>
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<i>> </i><br>
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<i>> As for the other situations, it could be possible that they might have an</i><br>
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<i>> older rev of the firmware.</i><br>
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<p>
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<p>
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No. I think I figured out what happened.<br>
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<p>
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AppleScanner which has only 256 bytes for buffer so it usually sets the<br>
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blocking bit when used with the defaults settings (LineArt, 75dpi=64k).<br>
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So I had never problem since the scanner was blocking and the read<br>
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procedure was continuing. But If you have large buffers it is possible<br>
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to end the scan and the buffer hadn't filled up (half of the buffer<br>
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actually). Thus the resulting bug you found. The others may be issued<br>
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scans which may result to smaller images than the buffer, so they didn't<br>
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notice any data exchange as you did.<br>
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<p>
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I' ll try your patch today and if it works I will include it to the<br>
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changes for the next SANE versions. In the mean time feel free to send<br>
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me anything you got.<br>
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<p>
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<i>> You had mentioned that someone had worked on getting color support</i><br>
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<i>> working, then mailed you the code mentioning that he didn't have the time</i><br>
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<i>> to fully maintain it. That's the code I am keenly interested in working</i><br>
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<i>> on, since I have the Color OneScanner.</i><br>
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<p>
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You are referring to an older post that I sent accidentally, before I<br>
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was able to correct the various syntax errors I have made.<br>
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<p>
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Here is the original:<br>
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<p>
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<i>> Finally there was one guy that he claimed that he had quick/hacked a</i><br>
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<i>> program to scan from ColorOneScanners. I asked him if it was possible to</i><br>
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<i>> built some of his knoweledge in the SANE backend. He said that he had no</i><br>
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<i>> time for such a task, but he could send me the code. I said OK, fine</i><br>
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<i>> thanks. Well I saw that code as much as did. I think that was</i><br>
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<p>
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and here what I was intended to write. Sorry for the trouble.<br>
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<p>
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Finally there was one guy that he claimed that he had quick/hacked a<br>
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program to scan from ColorOneScanners. I asked him if it was possible<br>
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to built some of his knowledge in the SANE backend. He said that he had<br>
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no time for such a task, but he could send me the code. I said OK, fine<br>
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thanks. Well I saw that code as much as you did. I think that was last<br>
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year.<br>
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<p>
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If you want to work on ColorOneScanners be my guest. I will include<br>
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every patch you send me assumed that you are not breaking the<br>
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AppleScanner part. The sane-0.74 backend/apple.c with your patch is the<br>
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most recent sources that it is public available AFAIK.<br>
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<p>
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Milon Firikis<br>
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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="0062.html">Kjetil Torgrim Homme: "What works best?"</a>
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||
<li> <b>Previous message:</b> <a href="0060.html">Bernd Schroeder: "Re: ADF for microtek2 backend"</a>
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<li> <b>Maybe in reply to:</b> <a href="0023.html">Ian R. Justman: "Apple OneScanner/Color OneScanner status?"</a>
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<!-- nextthread="start" -->
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<!-- reply="end" -->
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</ul>
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