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RE: filmscanners: Cleaning slides (PEC tips)
> However, I wonder how ICE can compensate for fingerprints that are
> in the shape of the emulsion: I thought it just detected opaque
> material.
>
One of the subtle points about ICE is that it works with defects that block
just a portion of the IR light. From the patent, ICE measures the amount of
IR that is transmitted through each pixel. It scales the RGB according to
how much of the IR was blocked, using different scaling for each color to
account for how much of the IR each dye blocks. For pixels where too much
of the IR was blocked, indicating that the RGB data is invalid, a separate
routine is used to fill the bad region using the surrounding good RGB
values.
Thus, fine scratches, dust spots and semi-opaque fingerprints are restored
to their original color, although with increased noise. Big, opaque
splotches are first filled in around the their edges - where their is still
enough RGB information to estimate the correct values. The central core,
where there is no valid RGB information, is filled in from the previously
restored boundary.
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