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<H1>Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)</H1>
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<STRONG>From:</STRONG> Dave Hill (<A HREF="mailto:dave@minnie.demon.co.uk?Subject=Re:%20Xsane-0.55:%20scan%20resolution%20selection%20(Epson%201200S,%20CVS%20Sane)&In-Reply-To=&lt;38AEE327.3F1CD802@minnie.demon.co.uk&gt;"><EM>dave@minnie.demon.co.uk</EM></A>)<BR>
<STRONG>Date:</STRONG> Sat Feb 19 2000 - 10:38:31 PST
<P>
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<LI><STRONG>Reply:</STRONG> <A HREF="0244.html">Oliver Rauch: "Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)"</A>
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Karl Heinz Kremer wrote:
<BR>
<EM>&gt;
</EM><BR>
<EM>&gt; On Sat, Feb 19, 2000 at 01:23:49PM +0100, Oliver Rauch wrote:
</EM><BR>
<EM>&gt; &gt; Hello Karl Heinz,
</EM><BR>
<EM>&gt; &gt;
</EM><BR>
<EM>&gt; &gt; the sane standard defines only one &quot;resolution&quot; as well known option.
</EM><BR>
<EM>&gt; &gt; It does not make sense to have a &quot;preview resolution&quot; option because
</EM><BR>
<EM>&gt; &gt; the frontend has to set the correct resolution in each case and like defined
</EM><BR>
<EM>&gt; &gt; in the standard xscanimage and xsane do set the option &quot;resolution&quot;.
</EM><BR>
<EM>&gt; &gt;
</EM><BR>
<EM>&gt; &gt; If the preview resolution option is removed from the epson backend
</EM><BR>
<EM>&gt; &gt; everything will work fine.
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; OK, so let me see if I understand this correctly: I don't have to set
</EM><BR>
<EM>&gt; the preview resolution in the backend, this is done in the frontend.
</EM><BR>
<EM>&gt; Therefore it does not make sense to have a &quot;preview resolution&quot; selection.
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; If this assumtion is correct I can remove the preview resolution.
</EM><BR>
<EM>&gt; I do however doubt that &quot;everything will work fine&quot; after I remove
</EM><BR>
<EM>&gt; that option. You still don't know which resolutions are supported
</EM><BR>
<EM>&gt; by the scanner if I implement the resolution option as a range vs.
</EM><BR>
<EM>&gt; as a list. So the resolution list will still display a &quot;synthetic&quot;
</EM><BR>
<EM>&gt; set of resolutions.
</EM><BR>
<EM>&gt;
</EM><BR>
<P>The &quot;preview resolution&quot; was added by Christian I think. I never
<BR>
did work out the reason why.
<BR>
<P>If you have no preview resolution, xsane will pick a suitable
<BR>
resolution depending on the area you want to scan, i.e. as you
<BR>
zoom in, the preview gets more detailed. This is what you normally
<BR>
want!
<BR>
<P>With the preview resolution setting, you have to increase the
<BR>
resolution by hand if you want to see detail when you zoom in,
<BR>
but if you forget to reset it and try and do a full-page preview,
<BR>
xsane runs out of memory, tries to abort the scan and the scanner
<BR>
locks up (power cycle required).
<BR>
<P>I don't know what xscanimage does though, I haven't checked. It
<BR>
probably does the same thing.
<BR>
<P>You are correct that xsane &quot;manufactures&quot; the resolution list, it
<BR>
has no idea what resolutions are actually supported by the backend,
<BR>
only the &quot;min&quot;, &quot;max&quot; and &quot;quant&quot; values returned. The epson backend
<BR>
sets &quot;quant&quot; to zero, which (I think) means &quot;any resolution will do&quot;,
<BR>
so xsane happily makes up a list!
<BR>
<P>In fact, the scanner *will* do any resolution you want, not just
<BR>
the ones it tells you about (at least my GT7000 does, the book says
<BR>
&quot;50 to 4800 in 1 DPI increments, plus 7200 &amp; 9600 with zoom&quot;).
<BR>
This is why I queried Christian's extra code for clamping the
<BR>
resolution to one of the scanner's values a while ago.
<BR>
<P>There is an alternative, instead of returning &quot;min&quot;, &quot;max&quot; and &quot;quant&quot;,
<BR>
you can return the actual list instead, changing the type from
<BR>
CONSTRAINT_LIST to WORD_LIST. See the agfafocus backend for more
<BR>
on this. Xsane has code to handle this case as well as the
<BR>
CONSTRAINT_LIST version, so I assume that it will display the
<BR>
correct resolution list (although the code says &gt; 50, so 50 DPI
<BR>
isn't included(!), and you only get 20 items max). Could be worth
<BR>
an #ifdef in the backend to try it.
<BR>
<P>Sorry, I'm rambling... I hope that's right!
<BR>
<P>Dave
<BR>
<P><PRE>
--
Dave Hill, Kempston, Bedford UK <A HREF="mailto:dave@minnie.demon.co.uk?Subject=Re:%20Xsane-0.55:%20scan%20resolution%20selection%20(Epson%201200S,%20CVS%20Sane)&In-Reply-To=&lt;38AEE327.3F1CD802@minnie.demon.co.uk&gt;">dave@minnie.demon.co.uk</A>
Sicth munce ago, I cutn't evun spel enjuneer, and now I are one!
<P><P>--
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<LI><STRONG>Next message:</STRONG> <A HREF="0234.html">Peter Kirchgessner: "Re: HP scanjet 6200C horizontal banding in color"</A>
<LI><STRONG>Previous message:</STRONG> <A HREF="0232.html">Petter Reinholdtsen: "Re: New CVS snapshot 20000213"</A>
<LI><STRONG>In reply to:</STRONG> <A HREF="0222.html">Karl Heinz Kremer: "Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0239.html">Karl Heinz Kremer: "Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)"</A>
<LI><STRONG>Reply:</STRONG> <A HREF="0239.html">Karl Heinz Kremer: "Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)"</A>
<LI><STRONG>Reply:</STRONG> <A HREF="0244.html">Oliver Rauch: "Re: Xsane-0.55: scan resolution selection (Epson 1200S, CVS Sane)"</A>
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