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<TITLE>sane-devel: Re: some technical questions</TITLE>
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<META NAME="Author" CONTENT="Henning Meier-Geinitz (hmg-ml@gmx.de)">
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<H1>Re: some technical questions</H1>
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<STRONG>From:</STRONG> Henning Meier-Geinitz (<A HREF="mailto:hmg-ml@gmx.de?Subject=Re:%20some%20technical%20questions&In-Reply-To=<20010118230458.A10952@vortex.swb.de>"><EM>hmg-ml@gmx.de</EM></A>)<BR>
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<STRONG>Date:</STRONG> Thu Jan 18 2001 - 14:04:58 PST
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<P>
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<LI><STRONG>Next message:</STRONG> <A HREF="0190.html">Henning Meier-Geinitz: "Re: Lifetec LT9385"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0188.html">volodya@mindspring.com: "some technical questions"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0188.html">volodya@mindspring.com: "some technical questions"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0200.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0196.html">dave-mlist@bfnet.com: "Failed to open device `coolscan:/dev/scanner': Device busy."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0200.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0271.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<P>
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Hi,
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<BR>
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<P>On Thu, Jan 18, 2001 at 03:54:31PM -0500, <A HREF="mailto:volodya@mindspring.com?Subject=Re:%20some%20technical%20questions&In-Reply-To=<20010118230458.A10952@vortex.swb.de>">volodya@mindspring.com</A> wrote:
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<BR>
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<EM>> * I think I found 3 sets of data that looks like gamma. Does it make
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</EM><BR>
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<EM>> sense ?
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</EM><BR>
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<P>Yes, that may be ok for color mode. Most scanners I use have 4096
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<BR>
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bytes of gamma (per color) so they use a mapping of 4096->256.
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<BR>
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<P><EM>> * The scanner is said to be 30 (or 32 ?) bit but I only get 24bit data
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</EM><BR>
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<EM>> is it supposed to be so ?
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</EM><BR>
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<P>That's probably marketing speech. The 30 (or 36, 48) bits are used
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<BR>
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internally. After calibration + gamma correction 24 bits are returned
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<BR>
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to the computer. Some scanners allow to transmit the raw data with the
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<BR>
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higher bits/pixel but then calibration/gamma isn't used (at least in
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<BR>
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my experience).
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<BR>
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<P><EM>> * there are also some registers that drive the motor - I can use them
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</EM><BR>
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<EM>> but if there are some general ideas about how they should work I'll
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</EM><BR>
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<EM>> be happy to listen
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</EM><BR>
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<P>That's quite dependent on the chip the scanner uses. Maybe it helps to
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<BR>
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look at a paper about stepper motors.
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<BR>
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<P><EM>> * I don't understand how sensor is switched from 75dpi mode to higher
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</EM><BR>
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<EM>> dpi mode. (i.e. I can drive the carriage at different resolutions,
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</EM><BR>
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<EM>> but I don't know how to get the sensor to output higher precision
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</EM><BR>
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<EM>> data)
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</EM><BR>
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<P>As far as I see at the Mustek scanners the sensor always scans at the
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<BR>
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maximum resolution. Only the data is reduced somewhere in the scanner
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<BR>
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when lower resolutions are used.
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<BR>
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<P>Can I add an entry in the PROJECTS file of SANE for you? So no work is
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<BR>
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duplicated.
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<BR>
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<P>Is the chip(set) used by canon produced by them or from another vendor?
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<BR>
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<P><P>Bye,
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<BR>
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Henning
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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:%20some%20technical%20questions&In-Reply-To=<20010118230458.A10952@vortex.swb.de>">majordomo@mostang.com</A>
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</PRE>
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<UL>
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<!-- next="start" -->
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<LI><STRONG>Next message:</STRONG> <A HREF="0190.html">Henning Meier-Geinitz: "Re: Lifetec LT9385"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0188.html">volodya@mindspring.com: "some technical questions"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0188.html">volodya@mindspring.com: "some technical questions"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0200.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0196.html">dave-mlist@bfnet.com: "Failed to open device `coolscan:/dev/scanner': Device busy."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0200.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0271.html">volodya@mindspring.com: "Re: some technical questions"</A>
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<EM>
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This archive was generated by <A HREF="http://www.hypermail.org/">hypermail 2b29</A>
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: <EM>Thu Jan 18 2001 - 14:09:43 PST</EM>
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