On 27 Oct 2004 09:16:49 -0700, (Lorenzo J.
Lucchini) wrote:

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*.

I really like your lateral thinking (well done!!!). Unfortunately,
using the flatbed to scan first as transparency and then laying the
film on the scanner and scanning as reflective introduces far too many
problems to be effective.

Besides the obvious such as flaws (both scratches and dust) on top of
the film which will not be detected in the reflective scan, there are
other far more serious problems, in particular alignment.

Regarding flaws within the film itself (e.g. scratches) the alignment
between the two scans will be way off on both axis. Indeed, there are
bound to be all sorts of spatial distortions and I would expect the
two images to be of totally different sizes making it impossible to
accurately superimpose in order to identify the flaws.

Regarding surface particles (e.g. dust), once you've moved the film
you've dislodged some dust and introduced other. Therefore, surface
debris between the two scans will not correspond anymore. In other
words, you'd be "cleaning" dust which doesn't exist and, yet, leaving
dust which does.

So in both instances (internal and external flaws) the alignment,
which is the cornerstone of the method, will itself be flawed.

Nevertheless, I really must commend you again on creative thinking!

Don.