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filmscanners: RE: filmscanners: Infrared dust removal accuracy

Darrell wrote:
>I have some vague idea of how infrared scanning is used to remove dust
>scratches from film scans on scanners that have this capability. Is there
>any possibility that this method could mistake elements of the actual image
>on the film for the undesirable dust or scratch and thereby "remove" parts
>of the photographic image?

Not with a colour slide or negative film. Chromogenic films should be fine,
as should be slides but some of the more dense slide films may have problems
- eg. Kodachrome.  It depends on how much of the image is visible in Infra-red.
 Silver based B&W film images are not transparent to IR so they don't work.

> Has anyone had observations or done any testing in this regard?
> Perhaps photographinq a high contrast texture or the white
> fluff from poplar trees floating in the air aqainst a dark
> background and then surgically placing lint on one half the
> film to be scanned for comparison?

I haven't done a test like this but I have recently looked at the IR component
of scans from a number of different types of film.  The only respect in
which I've seen the real image being adversely affected by IR dust and scratch
removal is a softening of the image overall.

> I am currently "stuck" with an Artixscan 4000T which, of course,
> does not have this capability as far as I know.

No, the Artixscan 4000T and the Polaroid SS4000 don't have an IR channel.


Rob Geraghty harper@wordweb.com


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