[filmscanners] Re: Newish Digital Tech

["Karl Schulmeisters" <karlsch@earthlink.net>]

That's not how the Foveon chip works.  There are no filters. They are taking
advantage of the fact that different light frequencies have different depth
penetrations into silicon.  This is likely in part what is causing the color
rendition problems.  Essentially there is not going to be as clean a
differentiation between the amount of light at the R,G and B sites, and they
are relying on subractive calculation to compute the R and G values.  Since
the photo-electric effect is a statistical (quantum) phenomenon, I can see
this being a source of sensor error.
----- Original Message -----
From: "Paul D. DeRocco" <pderocco@ix.netcom.com>
To: <karlsch@earthlink.net>
Sent: Tuesday, January 14, 2003 10:16 AM
Subject: [filmscanners] RE: Newish Digital Tech


> From: David J. Littleboy
>
> > Color rendition is problematic in the SD9...

That may just be an implementation problem with that particular camera. It
seems to me that any sensor that has has three filters with overlapping
bell-shaped spectral responses, centered on red, green and blue, is capable
of resolving all colors visible to the eye, given an appropriate profile.
After all, any color of perfectly saturated (i.e., laser) light will produce
a different combination of three numbers from the sensor, so suitable
arithmetic can turn these into perfectly saturated RGB values. The wider the
bandwidth of each filter, the more the colors will mix, requiring a larger
apparent gamut in the profile to compensate, but it can still be compensated
for.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

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