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<!-- received="Fri Oct 23 09:37:45 1998 PDT" -->
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<!-- sent="Fri, 23 Oct 1998 03:52:30 -0600" -->
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<!-- name="Sean Reifschneider" -->
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<!-- subject="Scan Size Clarification and JPEG/whatever format data" -->
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<title>sane-devel: Scan Size Clarification and JPEG/whatever format data</title>
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<h1>Scan Size Clarification and JPEG/whatever format data</h1>
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<b>Sean Reifschneider</b> (<a href="mailto:jafo@tummy.com"><i>jafo@tummy.com</i></a>)<br>
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<i>Fri, 23 Oct 1998 03:52:30 -0600</i>
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<p>
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<li> <b>Next message:</b> <a href="0258.html">David Mosberger-Tang: "Re: Scan Size Clarification and JPEG/whatever format data"</a>
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<li> <b>Previous message:</b> <a href="0256.html">Andreas Tille: "Coolscan driver produces error at the image border"</a>
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It's not entirely clear to me from the draft document how soon after<br>
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doing a "start scan" that it's expected the X and Y image size will<br>
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be known. The back-end I'm working on right now doesn't actually<br>
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have the exact size (only an estimate because of auto-page-size<br>
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detection) until after the first data read has completed.<br>
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<p>
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I suspect that some front-ends will expect it to be accurate before<br>
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reading the first data-block (for writing a header or allocating<br>
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the image buffer).<br>
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<p>
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Also, in the JPEG/MPEG/RAW image format arena... I would propose that<br>
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the only additional image type to be added be "RAW", with a standard<br>
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option presenting the available image formats. The front end would<br>
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then request a specific format through the normal channels, the back-end<br>
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would send it as RAW, and the front-end would either decode it or<br>
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just write the raw bits to a file.<br>
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<p>
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This is in keeping with the idea that the protocol just be the medium<br>
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which the frontend and backend communicate. If a back-end implements,<br>
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say, G3 compression, and the front-end knows how to handle that, it's<br>
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not an issue. As soon as you encode these values into SANE itself,<br>
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you get into the business of having to track everyone's pet format.<br>
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<p>
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For the time being, it looks like I'll implement this using just the<br>
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standard GREY format.<br>
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<p>
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Also, any suggestions on the best back-end to use as a model for a new<br>
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one would be appreciated.<br>
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<p>
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Thanks,<br>
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Sean<br>
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<pre>
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--
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A smart terminal is not a smart*ass* terminal, but rather a terminal
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you can educate. -- Rob Pike
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Sean Reifschneider, Inimitably Superfluous <<a href="mailto:jafo@tummy.com">jafo@tummy.com</a>>
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URL: <<a href="http://www.tummy.com/xvscan">http://www.tummy.com/xvscan</a>> HP-UX/Linux/FreeBSD/BSDOS scanning software.
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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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<p>
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<ul>
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<!-- next="start" -->
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<li> <b>Next message:</b> <a href="0258.html">David Mosberger-Tang: "Re: Scan Size Clarification and JPEG/whatever format data"</a>
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<li> <b>Previous message:</b> <a href="0256.html">Andreas Tille: "Coolscan driver produces error at the image border"</a>
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<!-- nextthread="start" -->
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