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<TITLE>sane-devel: [snapscan] High resolution scanning</TITLE>
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<META NAME="Author" CONTENT="Oliver Schwartz (Oliver.Schwartz@gmx.de)">
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<META NAME="Subject" CONTENT="[snapscan] High resolution scanning">
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<H1>[snapscan] High resolution scanning</H1>
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<!-- received="Tue Apr 10 15:01:37 2001" -->
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<!-- sent="Tue, 10 Apr 2001 23:25:54 +0200" -->
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<!-- isosent="20010410212554" -->
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<!-- name="Oliver Schwartz" -->
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<!-- email="Oliver.Schwartz@gmx.de" -->
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<!-- subject="[snapscan] High resolution scanning" -->
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<!-- id="01041023255400.17340@oliverspc" -->
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<STRONG>From:</STRONG> Oliver Schwartz (<A HREF="mailto:Oliver.Schwartz@gmx.de?Subject=Re:%20[snapscan]%20High%20resolution%20scanning&In-Reply-To=<01041023255400.17340@oliverspc>"><EM>Oliver.Schwartz@gmx.de</EM></A>)<BR>
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<STRONG>Date:</STRONG> Tue Apr 10 2001 - 14:25:54 PDT
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<P>
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<LI><STRONG>Next message:</STRONG> <A HREF="0113.html">Karsten Festag: "Re: [dev] New and updated backends"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0111.html">jean-louis Imbert: "Fwd: sane carte NRC53c400a"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0117.html">Rainer Hantsch: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0117.html">Rainer Hantsch: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0119.html">Sebastien Sable: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0120.html">Oliver Schwartz: "Re: [snapscan] High resolution scanning"</A>
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<HR NOSHADE><P>
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<P>
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Hi,
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<BR>
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<P>is there anybody out there who's successfully using the snapscan backend with
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<BR>
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resolutions of 1200 dpi and above? It doesn't work for me, and if I'm not
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<BR>
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mistaken for no one else either.
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<BR>
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<P>I looked into this and found that
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<BR>
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<P>1) x-resolution can only be increased up to the optical resolution. It's
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<BR>
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possible to request higher resolution from the scanner, but it will only
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<BR>
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return the image data with maximum resolution padded with junk. On my
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<BR>
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scanner, which has an optical resolution of 600dpi, this means that for a
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<BR>
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scan in 1200 dpi I get the scanned data on the left half of the image and
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<BR>
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junk in the right half of the image. However, it's possible that there are
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<BR>
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some scanners out there that do an interpolation in their firmware - anybody
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<BR>
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seen this?
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<BR>
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<P>2) Performing a scan on a wide scan area with high resolution will lead to a
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<BR>
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hanging backend, because the size of one image line becomes larger than twice
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<BR>
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the size of the SCSI buffer. Some computations inside the backend calculate
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<BR>
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bufferSize/lineSize, which will evaluate to zero - the rest is left to your
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<BR>
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imagination.
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<BR>
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<P>The best solution is probably to use different resolutions in x and y
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<BR>
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dimension. The x resolution may than be increased up to the optical
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<BR>
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resolution, which avoids problem (2). If a frontend requests a higher
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<BR>
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resolution the backend can use some decent interpolation algorithm.
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<BR>
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<P>This will probably take some time to implement. Until then, I suggest to
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<BR>
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disable the higher resolutions to avoid problems. If however there are
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<BR>
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scanners with firmware interpolation those resolution settings can be left
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<BR>
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untouched.
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<BR>
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<P>Oliver
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<BR>
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<P><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?Subject=Re:%20[snapscan]%20High%20resolution%20scanning&In-Reply-To=<01041023255400.17340@oliverspc>">majordomo@mostang.com</A>
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</PRE>
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<P><!-- body="end" -->
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<HR NOSHADE>
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<UL>
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<!-- next="start" -->
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<LI><STRONG>Next message:</STRONG> <A HREF="0113.html">Karsten Festag: "Re: [dev] New and updated backends"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0111.html">jean-louis Imbert: "Fwd: sane carte NRC53c400a"</A>
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<!-- nextthread="start" -->
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0117.html">Rainer Hantsch: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0117.html">Rainer Hantsch: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0119.html">Sebastien Sable: "Re: [snapscan] High resolution scanning"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0120.html">Oliver Schwartz: "Re: [snapscan] High resolution scanning"</A>
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This archive was generated by <A HREF="http://www.hypermail.org/">hypermail 2b29</A>
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: <EM>Tue Apr 10 2001 - 15:03:26 PDT</EM>
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