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<TITLE>sane-devel: Re: snapscan 1212u_2 problems</TITLE>
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<H1>Re: snapscan 1212u_2 problems</H1>
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<STRONG>From:</STRONG> Lawrence Glaister (<A HREF="mailto:lg@jfm.bc.ca?Subject=Re:%20snapscan%201212u_2%20problems&In-Reply-To=&lt;00d001c06fa5$d70cc840$bf0aa8c0@dufusiii&gt;"><EM>lg@jfm.bc.ca</EM></A>)<BR>
<STRONG>Date:</STRONG> Tue Dec 26 2000 - 17:39:23 PST
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the color image may be a little smaller by up to several lines. The reason
<BR>
for this is that the sensor is reading the color information from slightly
<BR>
offset positions on the page and the scanner software (snapscan driver)
<BR>
attempts to reregister the lines of data. In other words, the line of red
<BR>
scan data may need to be combined with the green data from 3 scan lines
<BR>
later in the data flow. Because of this, the scanner may scan 500 * 3 lines
<BR>
but only 497 triplets of aligned data may come out of the driver.... some
<BR>
gets discarded because it doesn't have all 3 color bands available. Even at
<BR>
high scan resolutions, it looks like there should be 6 or less lines
<BR>
discarded. I did put a print statement in my driver to see what the offsets
<BR>
were and they mostly showed up as 2 or 3 lines depending on resolution. I
<BR>
have never had scan data messed up like the picture you sent me... I suspect
<BR>
there have been some changes which broke the 1212u driver more than it
<BR>
already was. If I get a chance in the next few days, I will download the
<BR>
latest snapscan driver and sane 1.0.4 and see if I can get it running again.
<BR>
Its probably worth having our discussions on the sane maillist so that more
<BR>
people are aware of the problem.
<BR>
=======================================================
<BR>
Lawrence Glaister VE7IT email: <A HREF="mailto:lg@jfm.bc.ca?Subject=Re:%20snapscan%201212u_2%20problems&In-Reply-To=&lt;00d001c06fa5$d70cc840$bf0aa8c0@dufusiii&gt;">lg@jfm.bc.ca</A>
<BR>
1462 Madrona Drive <A HREF="http://jfm.bc.ca">http://jfm.bc.ca</A>
<BR>
Nanoose Bay BC Canada
<BR>
V9P 9C9
<BR>
=======================================================
<BR>
----- Original Message -----
<BR>
From: John Coppens &lt;<A HREF="mailto:jcoppens@linux2.uccor.edu.ar?Subject=Re:%20snapscan%201212u_2%20problems&In-Reply-To=&lt;00d001c06fa5$d70cc840$bf0aa8c0@dufusiii&gt;">jcoppens@linux2.uccor.edu.ar</A>&gt;
<BR>
To: Lawrence Glaister &lt;<A HREF="mailto:lg@jfm.bc.ca?Subject=Re:%20snapscan%201212u_2%20problems&In-Reply-To=&lt;00d001c06fa5$d70cc840$bf0aa8c0@dufusiii&gt;">lg@jfm.bc.ca</A>&gt;
<BR>
Sent: Tuesday, December 26, 2000 2:53 PM
<BR>
Subject: Re: A few questions
<BR>
<P><P><EM>&gt; On Mon, 25 Dec 2000 20:16:08 -0800 &quot;Lawrence Glaister&quot; &lt;<A HREF="mailto:lg@jfm.bc.ca?Subject=Re:%20snapscan%201212u_2%20problems&In-Reply-To=&lt;00d001c06fa5$d70cc840$bf0aa8c0@dufusiii&gt;">lg@jfm.bc.ca</A>&gt;
</EM><BR>
wrote/El dddd&gt; Hi John,
<BR>
<EM>&gt; &gt; ok, great, we are using the same scanner. I have the &quot;upload required&quot;
</EM><BR>
<EM>&gt; &gt; version as well. I plugged it into my ups and only have to reload every
</EM><BR>
few
<BR>
<EM>&gt; &gt; months when we get a really nasty power day. I posted some fixes to the
</EM><BR>
<EM>&gt; &gt; 1.0.3 snapscan version that were hacks, but got me going. I had two
</EM><BR>
<EM>&gt; &gt; problems, one, the scanner software would hang in an infinite loop
</EM><BR>
during
<BR>
<EM>&gt; &gt; scsi speed calibration and another where the usb status returned EAGAIN.
</EM><BR>
I'm
<BR>
<EM>&gt; &gt;...
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; Hi Lawrence
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; After some difficult experimenting (because of 36C temperatures) I did
</EM><BR>
<EM>&gt; find something strange.
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; I scanned an image at 50bpi, same format, in gray, b/w, and color. I then
</EM><BR>
<EM>&gt; checked the size of the image received from the scanner, summing the WROTE
</EM><BR>
<EM>&gt; statements of the debug output. I get correct numbers for b/w, and
</EM><BR>
grayscale,
<BR>
<EM>&gt; but the color image is off:
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; Summing WROTEs: 724599 bytes
</EM><BR>
<EM>&gt; The image should be: 723330 bytes (570 x 1269bytes/line,
</EM><BR>
<EM>&gt; as reported in the same debug output)
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; That's one line difference (1269 bytes).
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; Now, if I only could determine where this difference comes from... Any
</EM><BR>
<EM>&gt; suggestions?
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; John
</EM><BR>
<EM>&gt; --
</EM><BR>
<EM>&gt;
</EM><BR>
<P><P><PRE>
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