[filmscanners] RE: Digital ICE

["Austin Franklin" <darkroom@ix.netcom.com>]

Hi Jack,

> Okay Austin, I've got the Doctor looking over my shoulder right
> now. He says
> that with MOST scanners (especially ccd) because of the pixels sensor
> density, there is light piping between sensors causing a loss of
> sharpness.

I don't believe it's light piping, but electronic crosstalk between adjacent
sensors, which is very dependant on color (red is worst, blue second worst
and green the best).  If it was lightpiping, I would think it would be the
same across all three colors.  Please run that buy the Dr.

> He is
> telling me
> that a drum scanner is an exception because it masks the light going into
> and out of the film.

Now that is interesting.  I understand the principle, but my experience, is
that drum scanners actually require more sharpening than high end CCDs...at
least that's what I've seen in scans I've done on both a Howtek 4500 and a
Leaf 45.  Though I agree, what you say makes sense theoretically.

I do agree that the color smearing isn't an issue with PMTs, as it is with
CCDs, simply because PMTs only "read" one pixel at a time, and therefore
there is no possibility of this type of crosstalk.

> Does this help?

I wanted to see if you had some other answer than I had.  I don't know that
I believe the lightpipe issue...we've always attributed it to what I stated.
If you (or anyone for that matter) or the Dr. have actually done
experimentation that shows it is lightpiping...I would like to know.  Since
I have not done any actual sensor design, I just use them, I have not done
any of this, but it would be interesting to know.

Regards,

Austin

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