kopia lustrzana https://gitlab.com/sane-project/website
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113 wiersze
4.4 KiB
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<!-- received="Mon Jun 28 00:46:56 1999 PDT" -->
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<!-- sent="Mon, 28 Jun 1999 09:45:30 +0200" -->
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<!-- name="Oliver Rauch" -->
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<!-- email="oliver.rauch@Wolfsburg.DE" -->
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<!-- subject="Re: calculation of bytes to read, bytes per line etc" -->
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<!-- inreplyto="calculation of bytes to read, bytes per line etc" -->
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<title>sane-devel: Re: calculation of bytes to read, bytes per line etc</title>
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<h1>Re: calculation of bytes to read, bytes per line etc</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>Mon, 28 Jun 1999 09:45:30 +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#221">[ date ]</a><a href="index.html#221">[ thread ]</a><a href="subject.html#221">[ subject ]</a><a href="author.html#221">[ author ]</a>
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<li> <b>Next message:</b> <a href="0222.html">Thomas Ziegler: "Re: xsane-26: Options for normal/fine were not saved"</a>
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<li> <b>Previous message:</b> <a href="0220.html">Meino Christian Cramer: "calculation of bytes to read, bytes per line etc"</a>
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<li> <b>Maybe in reply to:</b> <a href="0220.html">Meino Christian Cramer: "calculation of bytes to read, bytes per line etc"</a>
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<li> <b>Next in thread:</b> <a href="0226.html">abel deuring: "Re: calculation of bytes to read, bytes per line etc"</a>
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</ul>
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<!-- body="start" -->
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Meino Christian Cramer wrote:<br>
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<p>
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<i>> Hi all!</i><br>
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<i>></i><br>
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<i>> Currently I am programming a backend for</i><br>
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<i>> the AVISION AV630CS.</i><br>
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<i>></i><br>
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<i>> One problem appears, to which I have no idea</i><br>
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<i>> how to solve.</i><br>
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<i>></i><br>
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<i>> At different places of the code, things like</i><br>
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<i>> bytes per line, bytes per page, lines per page,</i><br>
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<i>> dots perl line etc are calculated.</i><br>
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<i>></i><br>
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<i>> Unfortunatly, there most be some round errors or</i><br>
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<i>> something like that, cause Xscanimage gets (or means)</i><br>
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<i>> a greater amount of bytes to read, than my scanner is</i><br>
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<i>> willing to send.</i><br>
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<p>
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Hi Meino,<br>
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<p>
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I had the same problems with umax scanners.<br>
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In the umax docs there is defined how to calculate<br>
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pixels/line and lines - although that sometimes does<br>
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not work too -<br>
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<p>
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The princip is the following:<br>
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The scanner has an Optical resolution (O) and you<br>
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want to scan with the resolution (S)<br>
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<p>
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Example:<br>
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Optical Resolution O=300 dpi<br>
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Scan Resolution: S=250 dpi<br>
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<p>
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If you scan a full inch, it is simple,<br>
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you get 250 pixels.<br>
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<p>
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If you only scan a part of an inch,<br>
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you must know which pixels are<br>
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used and which are thrown away.<br>
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<p>
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You can calculate this with:<br>
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INT[n * O/D]<br>
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<p>
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Example:<br>
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The (un)wanted pixles are<br>
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1. pixel = INT[0 * O/D]<br>
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2. pixel = INT[1 * O/D]<br>
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3. pixel = INT[2 * O/D]<br>
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4. pixel = INT[3 * O/D]<br>
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<p>
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The number of pixels in full inches is simple the dpi*full inches.<br>
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The last broken inch must be calculated the way above.<br>
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<p>
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You can download the recent update (build6) of the umax backend<br>
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from my homepage, in the function umax_calculate_pixels<br>
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the routine is implemented.<br>
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<p>
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There is still an error in it because I sometimes still have your problem,<br>
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but the number of errors is reduced by 90%!<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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<p>
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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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<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="0222.html">Thomas Ziegler: "Re: xsane-26: Options for normal/fine were not saved"</a>
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<li> <b>Previous message:</b> <a href="0220.html">Meino Christian Cramer: "calculation of bytes to read, bytes per line etc"</a>
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<li> <b>Maybe in reply to:</b> <a href="0220.html">Meino Christian Cramer: "calculation of bytes to read, bytes per line etc"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0226.html">abel deuring: "Re: calculation of bytes to read, bytes per line etc"</a>
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<!-- reply="end" -->
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</ul>
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