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<!-- received="Mon Apr 5 02:37:04 1999 PDT" -->
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<!-- sent="Sun, 04 Apr 1999 17:13:40 +0000" -->
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<!-- name="Jonathan A. Buzzard" -->
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<!-- email="jab@hex.prestel.co.uk" -->
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<!-- subject="Re: 16 bit per sample support" -->
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<!-- inreplyto="Pine.LNX.3.96.990404122354.30186A-100000@chef.ecs.soton.ac.uk" -->
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<title>sane-devel: Re: 16 bit per sample support</title>
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<h1>Re: 16 bit per sample support</h1>
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<b>Jonathan A. Buzzard</b> (<a href="mailto:jab@hex.prestel.co.uk"><i>jab@hex.prestel.co.uk</i></a>)<br>
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<i>Sun, 04 Apr 1999 17:13:40 +0000</i>
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<p>
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<ul>
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<li> <b>Messages sorted by:</b> <a href="date.html#77">[ date ]</a><a href="index.html#77">[ thread ]</a><a href="subject.html#77">[ subject ]</a><a href="author.html#77">[ author ]</a>
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<li> <b>Next message:</b> <a href="0078.html">Milon Firikis: "Re: Sane drivers"</a>
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<li> <b>Previous message:</b> <a href="0076.html">Jonathan A. Buzzard: "Re: Sane drivers"</a>
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<li> <b>Next in thread:</b> <a href="0082.html">Andreas Dilger: "Re: 16 bit per sample support"</a>
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<li> <b>Reply:</b> <a href="0082.html">Andreas Dilger: "Re: 16 bit per sample support"</a>
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<li> <b>Reply:</b> <a href="0085.html">Nick Lamb: "Re: 16 bit per sample support"</a>
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<!-- body="start" -->
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<a href="mailto:njl98r@ecs.soton.ac.uk">njl98r@ecs.soton.ac.uk</a> said:<br>
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<i>> >Possibly depending on the device this should be configurable. If I</i><br>
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<i>> >was scanning an X-ray at say 12bits I would be very upset if the</i><br>
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<i>> >backend then stretched it to 16bits.</i><br>
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<i>></i><br>
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<i>> I'm not sure why. The only (small) disadvantage is that there is an</i><br>
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<i>> increase in bandwidth from the backend to the frontend. For most</i><br>
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<i>> users, especially those looking for maximum performance, this is CPU</i><br>
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<i>> bandwidth, and thus very expendable. </i><br>
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<i>></i><br>
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<i>> There is no data loss (watch this...</i><br>
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<i>> 0xabc (12bit) --> 0xabca (16bit) --> 0xabc (12bit)</i><br>
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<i>> 0x123 (12bit) --> 0x1231 (16bit) --> 0x123 (12bit) </i><br>
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<p>
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Because you have mugged the values. X-rays where only an example, but the<br>
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same could be said of other sources such as aerial photography etc.<br>
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With these sorts of things you often want to do calculations on the<br>
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scanned images.<br>
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<p>
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For example I might have three Xrays of an object, that after some sort<br>
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of registration I wish to stack on top of one another. The Xrays have<br>
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been scanned say at 12 bits, now if you have stretched them though to<br>
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the full dynamic range of 16 bits adding the pixel values together<br>
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will result in loss of information. If they had stayed as 12 bits inside<br>
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a 16 bit value there is no problem.<br>
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<p>
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These are dozens of similar cases where stretching the values is simply<br>
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not acceptable. A little check button somewhere which can be unchecked<br>
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for those that don't want stretching would suffice.<br>
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<p>
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<p>
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JAB.<br>
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<p>
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<p>
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<pre>
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--
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Jonathan A. Buzzard Email: <a href="mailto:jab@hex.prestel.co.uk">jab@hex.prestel.co.uk</a>
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Northumberland, United Kingdom. Tel: +44(0)1661-832195
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<p>
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<p>
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<p>
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<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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<!-- body="end" -->
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<p>
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<ul>
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<!-- next="start" -->
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<li> <b>Next message:</b> <a href="0078.html">Milon Firikis: "Re: Sane drivers"</a>
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<li> <b>Previous message:</b> <a href="0076.html">Jonathan A. Buzzard: "Re: Sane drivers"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0082.html">Andreas Dilger: "Re: 16 bit per sample support"</a>
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<li> <b>Reply:</b> <a href="0082.html">Andreas Dilger: "Re: 16 bit per sample support"</a>
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<li> <b>Reply:</b> <a href="0085.html">Nick Lamb: "Re: 16 bit per sample support"</a>
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<!-- reply="end" -->
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</ul>
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