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<TITLE>sane-devel: 3091 backend: Brightness, Contrast etc.</TITLE>
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<META NAME="Author" CONTENT="Frederik Ramm (frederik@remote.org)">
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<META NAME="Subject" CONTENT="3091 backend: Brightness, Contrast etc.">
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<H1>3091 backend: Brightness, Contrast etc.</H1>
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<!-- received="Wed Mar 7 13:09:33 2001" -->
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<!-- isoreceived="20010307210933" -->
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<!-- sent="Wed, 7 Mar 2001 21:18:05 +0000" -->
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<!-- isosent="20010307211805" -->
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<!-- name="Frederik Ramm" -->
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<!-- email="frederik@remote.org" -->
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<!-- subject="3091 backend: Brightness, Contrast etc." -->
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<!-- id="20010307211805.A20763@aruba.remote.org" -->
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<STRONG>From:</STRONG> Frederik Ramm (<A HREF="mailto:frederik@remote.org?Subject=Re:%203091%20backend:%20Brightness,%20Contrast%20etc.&In-Reply-To=<20010307211805.A20763@aruba.remote.org>"><EM>frederik@remote.org</EM></A>)<BR>
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<STRONG>Date:</STRONG> Wed Mar 07 2001 - 13:18:05 PST
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<LI><STRONG>Previous message:</STRONG> <A HREF="0106.html">Fedor Karpelevitch: "HP ScanJet 3300Cse"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0112.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0112.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0113.html">Marian Eichholz: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0116.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<HR NOSHADE><P>
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<!-- body="start" -->
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<P>
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Hi,
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<BR>
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<P> the scanner I'm writing a backend for does not support the setting
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<BR>
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of the usual image-altering values like contrast, brightness, gamme
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<BR>
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correction etc.
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<BR>
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<P>Instead, you can load a so-called "LUT" translation table into the
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<BR>
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scanner. It's basically a mapping that assigns an output value to
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<BR>
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every possible input value. I.e. if I wanted a much brighter image, I
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<BR>
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would just download a table that maps
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<BR>
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<P>0 -> 50
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<BR>
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1 -> 51
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<BR>
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...
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<BR>
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204 -> 255
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<BR>
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205 -> 255
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<BR>
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206 -> 255
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<BR>
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...
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<BR>
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255 -> 255
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<BR>
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<P>or something similar. Since I don't have more than 8 bits on the input
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<BR>
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side, I cannot have the scanner do any translations that could not
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<BR>
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also be done afterwards (in fact, I could do in within the backend if
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<BR>
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I wanted to).
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<BR>
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<P>So, should I bother to "emulate" a brightness/contrast/gamma setting
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<BR>
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using these LUT tables? And if I should, can anyone point me to useful
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<BR>
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formulas that generate such translation tables for certain values of
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<BR>
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contrast, brightness etc.?
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<BR>
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<P><P>What's more, my scanner supports a few settings with funny names I
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<BR>
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cannot make sense of. Maybe somebody knows what they are, or what they
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<BR>
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might be. It would be interesting for me if it is worthwile to make
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<BR>
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them available through the backend.
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<BR>
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<P>* Initial Slice: Specifies the initial binary threshold value when in
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<BR>
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floating slice mode.
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<BR>
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* Up value: Specifies the +UP count value used in floating slice mode.
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<BR>
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(Valid settings: 0-3, default: 1)
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<BR>
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* Down value: ... as above
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<BR>
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* Lower Limit Slice: Specifies the lower limit slice used in floating
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<BR>
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slice mode (0-15, default: 6)
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<BR>
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* Compensation line Interval: Specifies the compensation line interval
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<BR>
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slice when in floating slice mode (0-15, default 0)
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<BR>
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* Error dispersion upper limit slice (0-255, default 230)
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<BR>
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* Error dispersion lower limit slice (0-255, default 20)
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<BR>
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* Laplacian coefficient for enhancement mode: 0 (weak), 1, 2 or 3
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<BR>
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(strong)
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<BR>
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* Gradient coefficient for enhancement mode: as above
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<BR>
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* Laplacian slice: Specifies which Laplacian slice is to be used for the
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<BR>
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enhancement mode (0-15)
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<BR>
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* Gradient slice: as above for Gradient slice
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<BR>
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* Primary Scan Ratio Compensation: on or off.
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<BR>
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<P>If anyone has the slightest idea...
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<BR>
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<P>Thanks
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<BR>
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Frederik
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<BR>
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<P><PRE>
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--
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Frederik Ramm ## eMail <A HREF="mailto:frederik@remote.org?Subject=Re:%203091%20backend:%20Brightness,%20Contrast%20etc.&In-Reply-To=<20010307211805.A20763@aruba.remote.org>">frederik@remote.org</A> ## N57<35>48.10' W005<30>40.32'
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<P><P>--
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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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<LI><STRONG>Next message:</STRONG> <A HREF="0108.html">Gabriele Conrad: "Acer 300F"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0106.html">Fedor Karpelevitch: "HP ScanJet 3300Cse"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0112.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0112.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0113.html">Marian Eichholz: "Re: 3091 backend: Brightness, Contrast etc."</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0116.html">Ulrich Deiters: "Re: 3091 backend: Brightness, Contrast etc."</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>Wed Mar 07 2001 - 13:11:21 PST</EM>
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