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<TITLE>sane-devel: Re: [snapscan] Core testing group</TITLE>
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<META NAME="Author" CONTENT="Steve Underwood (steveu@coppice.org)">
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<META NAME="Subject" CONTENT="Re: [snapscan] Core testing group">
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<H1>Re: [snapscan] Core testing group</H1>
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<STRONG>From:</STRONG> Steve Underwood (<A HREF="mailto:steveu@coppice.org?Subject=Re:%20[snapscan]%20Core%20testing%20group&In-Reply-To=<3A00BE63.CEEB540A@coppice.org>"><EM>steveu@coppice.org</EM></A>)<BR>
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<STRONG>Date:</STRONG> Wed Nov 01 2000 - 17:07:47 PST
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<P>
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<LI><STRONG>Next message:</STRONG> <A HREF="0018.html">Timo Hoderlein: "Re: Agfa Snapscan 310 color problem"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0016.html">Timothy Little: "Re: [snapscan] Testing Agfa 1212U"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0006.html">William L. Sebok: "Re: [snapscan] Core testing group"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0028.html">Werner Kolbeck: "Re: [snapscan] Core testing group"</A>
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<P>
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"William L. Sebok" wrote:
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<BR>
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<P><EM>> Steve Underwood <<A HREF="mailto:steveu@coppice.org?Subject=Re:%20[snapscan]%20Core%20testing%20group&In-Reply-To=<3A00BE63.CEEB540A@coppice.org>">steveu@coppice.org</A>> said
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</EM><BR>
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<EM>> > There seems to be a bit war in the scanner industry right now. We are
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</EM><BR>
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<EM>> > starting to see some outrageous numbers of bits quote. The best real values
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</EM><BR>
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<EM>> > are about 14 per color, or 42 overall. Anything more is fiction. In practice,
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</EM><BR>
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<EM>> > most scanners only send 8 bits per colour to the host. The rest are lost in
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</EM><BR>
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<EM>> > gamma correction witin the scanner.
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</EM><BR>
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<EM>>
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</EM><BR>
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<EM>> However, having enough bits to get a decent 8 bits after gamma correction
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</EM><BR>
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<EM>> is important, especially when trying to scan dark images or slides.
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</EM><BR>
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<P>Yes, I should not have said "lost in gamma correction". "Consumed in gamma
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<BR>
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correction" is more accurate. However, the noise floor of the CCD scanner makes
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<BR>
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extreme numbers of bits bogus. The have a 12 or 14 bit A/D, then interpolate up to
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<BR>
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16 bits, then gamma correct down to 8. Its really just a bogus set of calculations
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<BR>
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to be able to justify some high number of bits on the box. Scanners have for a
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<BR>
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long time offered ridiculous levels of interpolate pseudo-high resolution, because
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<BR>
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its cheap to do. Its of absolutely no use, though. High resolutions sound good,
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<BR>
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until you find a scan with take a gigabyte or so!
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<BR>
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<P>Regards,
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<BR>
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Steve
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<BR>
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<P><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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</PRE>
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<!-- next="start" -->
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<LI><STRONG>Next message:</STRONG> <A HREF="0018.html">Timo Hoderlein: "Re: Agfa Snapscan 310 color problem"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0016.html">Timothy Little: "Re: [snapscan] Testing Agfa 1212U"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0006.html">William L. Sebok: "Re: [snapscan] Core testing group"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0028.html">Werner Kolbeck: "Re: [snapscan] Core testing group"</A>
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This archive was generated by <A HREF="http://www.hypermail.org/">hypermail 2b29</A>
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: <EM>Wed Nov 01 2000 - 17:33:01 PST</EM>
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