[sane-devel] Epson 2400 and transparency scanning geometry

[bob]

On Tue, 2005-08-30 at 12:10 +0900, Olaf Meeuwissen wrote:
> Hi Bob,
> 
> Please Cc: sane-devel so your "ordeal" gets archived.

Will do.

> 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)?

After cutting the film strip to fit and going back and forth between the
flatbed and transparency unit settings a couple of times it did pick up
the correct location for the film strip.

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

I'm glad it was a simple problem, thank you so much for the help.

Bob
-- 
Dr. Robert J. Jerrard, Professor of Mathematics,
Concordia University College of Alberta,
7128 Ada Blvd., Edmonton, Alberta, T5B 4E4, Canada.
Phone: (780) 479-9291, Fax: (780) 474-1933.