[sane-devel] Color alignment Snapscan 600

[Oliver Schwartz]

Hi,

> A few months ago there were some (major?) changes in the snapscan backend.
> The changes made the backend much more stable (especially color scans and
> preview). With these changes a disalignment was introduced again. 

That's correct, but the disalignment was only broken for certain models 
(e.g. SnapScan 600), since they report positive signed color offsets ...

> It was
> fixed again just a few days ago (at the moment only available by cvs or the
> cvs-web-interface of sourceforge).

It's now also available as a release version (snapscan-20011129, 
http://sourceforge.net/project/showfiles.php?group_id=12742&release_id=63472).

> > Perhaps your scanner has a physical alignment problem.
>
> I hope it has not!
> But you are right, one pixel at maximum resolution isn't very much.

If, as you're saying, the yellow layer has to be moved to the *right*, than 
your scanner definitely has an alignment problem. At the moment only 
correction in y-dimension is done. The scanner, as far as I know, doesn't 
report any offsets in x-dimension, so that's probably a mechanical alignment 
problem of the three sensors. (But, to be fair, I can also notice a similar 
effect on my Acer 600UT. I have to boot Windows one of these days and see how 
the windows software handles it.)

Regards,

Oliver