[sane-devel] Epson 2400 and transparency scanning geometry

Olaf Meeuwissen olaf.meeuwissen at avasys.jp
Tue Aug 30 03:10:11 UTC 2005

Hi Bob,

Please Cc: sane-devel so your "ordeal" gets archived.

bob <rjerrard at math.concordia.ab.ca> writes:

> On Mon, 2005-08-29 at 09:39 +0900, Olaf Meeuwissen wrote:
>> Hmm, log data looks fine to me.  TPU area is reported fine.  48.26 mm
>> by 231.14 mm is big enough to scan a strip of 6 negatives (that's what
>> the product spec says it can).
> Size of the scan is fine, it is the location of the scan that is the
> problem.
>> Just to make sure, the area reported does not have its origin at the
>> same location as the flatbed scan area.  Maybe you are trying to set
>> scan areas based on the latter origin.  If so, you shouldn't.
> The origin of the preview is at the origin of the scan bed and so misses
> the negative completely.
>> The log data you sent indicated a mostly white (or black, depending on
>> whether you look at the scan data before or after conversion from
>> negative to positive).  Did you put an original on the scanner?
> There was a negative in the holder on the bed to be scanned. The point
> is that the preview missed it completely that is why the scan is mostly
> white.
>> What does a default TPU scan look like?  Can you put up an image so I
>> can take a look?
> Ok, have a look at a screen shot after the preview,
> http://www.math.concordia.ab.ca/~bob/Screen1.png
> and then after the default scan,
> http://www.math.concordia.ab.ca/~bob/Screen2.png
> There was a negative in the transparency holder at the time, have a look
> at the scanner with the lid up after the scan,
> http://www.math.concordia.ab.ca/~bob/Scanner.jpg
> As you can see the negative strip was in the holder in the center of the
> scanner under the transparency light but the scan location is not
> correct.

Yes, but I also note that the film strip stick out of the holder.  The
holder has special openings/slits for calibration purposes.  The one
for dia positives is visible on the top left of Scanner.jpg.  If the
film strip covers this calibration area, you will get strange scan
results.  I can't tell for sure, but it looks like your film strip
covers a calibration slit at the top.  What are the results when you
make sure your negative fits the holder (and does not stick out on
either side)?

> Any suggestions as to how to tell sane the correct location for the
> preview and scan?
> Thanks for the help, Bob

Hope this helps,
Olaf Meeuwissen                          EPSON AVASYS Corporation, LAN
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