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<TITLE>sane-devel: Re: Scan ahead</TITLE>
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<META NAME="Author" CONTENT="Stephen Williams (steve@icarus.com)">
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<META NAME="Subject" CONTENT="Re: Scan ahead">
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<H1>Re: Scan ahead</H1>
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<!-- received="Fri Mar 30 12:42:19 2001" -->
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<!-- name="Stephen Williams" -->
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<!-- subject="Re: Scan ahead" -->
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<STRONG>From:</STRONG> Stephen Williams (<A HREF="mailto:steve@icarus.com?Subject=Re:%20Scan%20ahead&In-Reply-To=<200103302054.MAA19579@icarus.com>"><EM>steve@icarus.com</EM></A>)<BR>
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<STRONG>Date:</STRONG> Fri Mar 30 2001 - 12:54:19 PST
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<LI><STRONG>Next message:</STRONG> <A HREF="0253.html">Oliver Rauch: "Re: big endian vs little endian"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0251.html">JFL Sane Dev: "RE: Scan ahead"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0250.html">Peter Kirchgessner: "Re: Scan ahead"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0256.html">Tom Martone: "Re: Scan ahead"</A>
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<A HREF="mailto:peter@kirchgessner.net?Subject=Re:%20Scan%20ahead&In-Reply-To=<200103302054.MAA19579@icarus.com>">peter@kirchgessner.net</A> said:
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<BR>
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<EM>> I dont know a scanner that can store a single frame completely. For an
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</EM><BR>
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<EM>> A4 scan at 600 dpi with 24bit you would need about 100MB of memory.
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</EM><BR>
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<P>I know several, and they are grayscale and color. And we keep building
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<BR>
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more because this pipelining really does help when you are talking about
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<BR>
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large batches. Of course, we are not talking about desk-top flat-bed
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scanners here:-)
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<P>And even on scanners that don't, it is possible that you want to start
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<BR>
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the engine moving the next page before you have all of the current page,
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because the mechanical latencies are such that you can get away with it.
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In the case of many scanners, this is the *only* way to get the rated
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speed. In these cases, it is up to the host driver to pull images out
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fast enough that you don't get overrun.
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<BR>
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<P>So Marius asked a valid question and I'm curious myself how this issue
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<BR>
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was dealt with by others. I suspect the answer is going to be something
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<BR>
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like "a child process does the pipelining."
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<BR>
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<PRE>
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--
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Steve Williams "The woods are lovely, dark and deep.
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<A HREF="mailto:steve@icarus.com?Subject=Re:%20Scan%20ahead&In-Reply-To=<200103302054.MAA19579@icarus.com>">steve@icarus.com</A> But I have promises to keep,
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<A HREF="mailto:steve@picturel.com?Subject=Re:%20Scan%20ahead&In-Reply-To=<200103302054.MAA19579@icarus.com>">steve@picturel.com</A> and lines to code before I sleep,
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<A HREF="http://www.picturel.com">http://www.picturel.com</A> And lines to code before I sleep."
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<P><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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To unsubscribe: echo unsubscribe sane-devel | mail <A HREF="mailto:majordomo@mostang.com?Subject=Re:%20Scan%20ahead&In-Reply-To=<200103302054.MAA19579@icarus.com>">majordomo@mostang.com</A>
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</PRE>
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<LI><STRONG>Next message:</STRONG> <A HREF="0253.html">Oliver Rauch: "Re: big endian vs little endian"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0251.html">JFL Sane Dev: "RE: Scan ahead"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0250.html">Peter Kirchgessner: "Re: Scan ahead"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0256.html">Tom Martone: "Re: Scan ahead"</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>Fri Mar 30 2001 - 12:42:36 PST</EM>
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