[sane-devel] problem with Nikon Coolscan II

[Richard Poole]

I have a Coolscan II connected to an Advansys ABP940U SCSI card. I
haven't owned this scanner from new and I've never seen it working
correctly. So I've no idea what's the source of the following weird
problem.

When I scan, using the coolscan backend, some lines of the scan are
offset by 1 pixel from the previous line; about 60% of lines, seemingly
at random, are affected, so after 24 lines I'm typically 14 or 15 pixels
across. After 62208 bytes (24 lines of grayscale or 8 of color), the
next line is back at the original position (62208 bytes is the amount of
information returned by the scanner from a single SCSI read). This
produces a jagged effect; http://guests.deus.net/~rp/sample.png shows the
top corner of a scan, showing the effect I've described at the edge
between a slide mount and a very light slide on a grayscale scan.

In color, I also notice that each line is only one color.
http://guests.deus.net/~rp/sample2.png - a picture is worth a thousand
words. That's from part of the middle of an image.

So my questions are:

- is this scanner functioning properly but being driven wrongly,
malfunctioning but usable, or a paperweight?

- if the scanner is OK, what is my best route to getting proper scans
from it? I'm happy to do some C programming, so I'd need to know what's
the best way to get specs and whether I should be working on the
coolscan or coolscan2 backends.

If there's any more information I can provide or tests I can carry out
to diagnose this problem, please let me know and I'll do so.
sane-backends 1.0.13, Red Hat Linux 7.3, kernel 2.4.18-3 .

Thanks,

Richard Poole