Wednesday, April 09, 2014

Foveon Quattro Resolution Expanations

Imaging Resource publishes an interview with Foveon's GM Shri Ramaswami explaining resolution enhancement claims of the latest Foveon Quattro sensor. Basically, the reason is that the top high resolution layer is "blue-heavy" rather than blue:

"You can see that the top layer is blue-heavy, but it's not blue. The next layer is green-heavy, but it isn't green. The bottom is red-heavy. None of these is just red, green, or blue -- that really allows you to do something very interesting. So this is fundamentally a pretty smart way to keep your information, but at the same time, reduce the whole load on the system, because these things are not pure colors. It may sound counterintuitive, but it actually allows you to separate out very cleanly all the detail information -- as we call it -- from the top layer, and understand where the color detail comes from. In other words, it allows us to actually get back what was apparently lost." Regarding the possibility to enhance resolution with a pure RGB sensitivity, Shri responds "It would be impossible then, without that correlation, to do this."


  1. What I can see from their sensitivity curves is that once IR-cut filter is applied, there will be huge overlap between G/B and almost completely overlap between G/R.

  2. The IR filter has always been a problem for Foveon. Still a nice Idea to capture luminance data from the blue green channel ih high res and still receiving at least 50% of the light then doing some nice math to add colour without too much noise. Probably not that accurate colour and low-res but nobody will be able to tell (JPG has proved that high-res luminance and low-res colour gives good results). Will even work better than bayer for reds on blue. I wonder if this will help the green corners which I suspect is caused by the non-standard IR filter.

  3. How did you get the conclusion that non-standard IR could cause green corners?

    1. The filter has a stronger green cast the greater the angle of incedence. Take a filter and slowly twist it to see the effect. The Sigma filter does this much ealier than normal.


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