"Digital ICE" without Digital ICE

First, sorry for cross-posting, I admit I just posted to the two
groups where the topic of Digital ICE seems to come up most often.

I'm a newcomer in digital photography and scanning, so the ideas I'll
discuss below might very well be badly flawed - please bear with me.

Ok, you have a flatbed scanner with a transparency adaptor; it's got
two lamps, one below the glass and one above. Film is supposed to be
scanned with the top lamp.

But what happend if you scan film with the bottom lamp, possibly with
the lid open and in a dark room?
The scan will show an almost completely black film, since nearly no
light passed through it. However, dust particles and white-ish
scratches on the film will (or might) reflect the light from the
bottom lamp, and thus will easily be spotted in the scan! (or will be
after some histogram normalization).

The rest is just a software process of applying dust-removal filters
on the spots in the image we know dust lies.


What do you think? I *have* actually tried this stuff and it *appears*
to work and remove a number of defects from the final image - although
many dust spots remains, and I haven't been able to find out whether
the system works differently with dust that's *on the film* and dust
that's *on the scanner*.

However, after cleaning the scanner's glass as carefully as I could, I
still think I'm spotting particles that do lie on the film surface.
Then maybe it also depends which side of the film dust lies on.


I'll post sample pictures and some sketched Bash scripts using NetPBM
for the actual picture cleaning if anybody's interested.


by LjL