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<TITLE>sane-devel: Re: Which scanners REALLY provide 36 bit output? HP?</TITLE>
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<META NAME="Author" CONTENT="Marko Cebokli (s57uuu@hamradio.si)">
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<META NAME="Subject" CONTENT="Re: Which scanners REALLY provide 36 bit output? HP?">
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<H1>Re: Which scanners REALLY provide 36 bit output? HP?</H1>
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<!-- received="Sat Dec 16 07:21:57 2000" -->
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<!-- name="Marko Cebokli" -->
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<STRONG>From:</STRONG> Marko Cebokli (<A HREF="mailto:s57uuu@hamradio.si?Subject=Re:%20Which%20scanners%20REALLY%20provide%2036%20bit%20output?%20HP?&In-Reply-To=<3A3B8B72.4AA3A84B@hamradio.si>"><EM>s57uuu@hamradio.si</EM></A>)<BR>
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<STRONG>Date:</STRONG> Sat Dec 16 2000 - 07:34:10 PST
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<P>
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<LI><STRONG>Next message:</STRONG> <A HREF="0180.html">Eugene Kanter: "scanimage and v4l"</A>
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<UL>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0178.html">Ben Millhouse: "RE: [snapscan] Vuego 620S and ACARD scsi card"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0177.html">Steve Underwood: "Re: Which scanners REALLY provide 36 bit output? HP?"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0188.html">Nick Lamb: "Waaay off topic (was Re: Which scanners REALLY provide 36 bit output? HP?)"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0071.html">Steve Underwood: "Re: Which scanners REALLY provide 36 bit output? HP?"</A>
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<HR NOSHADE><P>
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<P>
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Steve Underwood wrote:
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<BR>
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<EM>>
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</EM><BR>
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<EM>> What you need is not more bits. You need a spectral shift. Your stained documents
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</EM><BR>
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<EM>> might really come alive, if you look at them through a part of the spectrum we
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</EM><BR>
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<EM>> cannot see well. You may find colours (probably in the IR band) where the stains
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</EM><BR>
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<EM>> don't show at all, and the text is beautifully clear. If you try an IR filter you
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</EM><BR>
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<EM>> might get interesting results. Most glasses will pass the high end of the IR band,
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</EM><BR>
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<EM>> and I think the CCD in the scanner will respond OK when you do a black and white
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</EM><BR>
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<EM>> scan. If you can find a suitable filter, its worth a try.
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</EM><BR>
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<EM>>
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</EM><BR>
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<P>The best way for a quick experiment would probably be to use one of
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<BR>
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those old BW (handheld) scanners that have used red LEDs for
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<BR>
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illumination.
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<BR>
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Just replace the red LEDs with IR ones. You can find IR LEDs with
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<BR>
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dominant wavelengths between 800 and 950 nm. (TV remote stuff)
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<BR>
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<P>These scanners usually employ arrays of miniature SMD LEDs, so you'll
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<BR>
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need a steady hand for soldering :-)
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<BR>
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<P>The CCD chips actually have their peak sensitivity in the near IR in the
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<BR>
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same range, but it falls sharply below one micron, being quasi zero
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<BR>
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at 1100 nm.
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<BR>
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<P>A color scanner won't be adequate, because those have special IR
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<BR>
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blocking filters to prevent color falsification by the IR light.
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<BR>
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(or else the RGB color separation filters themselves are IR blocking)
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<BR>
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Selecting a BW scan on a color scanner doesn't change this.
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<BR>
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<P>Documents printed with old soot-containing inks should be nice in IR,
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<BR>
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but I'm not sure if modern color-process inks have any contrast in IR?
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<BR>
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<P>A quick way to see this would be to use a night-vision device and your
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<BR>
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TV remote as a torch in a dark room.
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<BR>
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<P>Enough crazy ideas -
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<BR>
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<P>regards,
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<BR>
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Marko Cebokli
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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:%20Which%20scanners%20REALLY%20provide%2036%20bit%20output?%20HP?&In-Reply-To=<3A3B8B72.4AA3A84B@hamradio.si>">majordomo@mostang.com</A>
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</PRE>
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<!-- next="start" -->
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<LI><STRONG>Next message:</STRONG> <A HREF="0180.html">Eugene Kanter: "scanimage and v4l"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0178.html">Ben Millhouse: "RE: [snapscan] Vuego 620S and ACARD scsi card"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0177.html">Steve Underwood: "Re: Which scanners REALLY provide 36 bit output? HP?"</A>
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<!-- nextthread="start" -->
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0188.html">Nick Lamb: "Waaay off topic (was Re: Which scanners REALLY provide 36 bit output? HP?)"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0071.html">Steve Underwood: "Re: Which scanners REALLY provide 36 bit output? HP?"</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>Sat Dec 16 2000 - 07:24:33 PST</EM>
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