Foveon sensor?

[Garbz]

Personally I think the comparison with anti-aliasing of computers is more confusing than helpful, because its a completely different thing.

The anti-aliasing of fotosensors is because fotosensors see the world through colored glasses (Bayer or Fuji X-Trans or whatever). Anti-aliasing helps to preserve color information which could otherwise be lost. So the question of anti-aliasing for fotosensors is finding the right amount of it, and too much is definitely bad, and you can leave it out like with the D800E and still get some kind of result.

Anti-aliasing on the computer is because the computer will compute the color of the middle point of the pixel. Not the sum of colors in each pixel, as our eyes or a camera would do. Anti-aliasing means the computer will compute the color of multiple points in the same pixel and color the pixel to the average color of these multiple points, thus getting closer, but obviously still not perfect, to what that color would look like would the scene be real and not just triangles forming surfaces painted with textures in a computer. In short, the more anti-aliasing on the computer, the better.

This is exactly the point I was trying to make. On a normal camera sensor the beyer filter requires an AA filter to prevent rainbow effects as small details fail to hit a group of 3 of the RGB pixels. Removing the AA filter on a beyer filter results in bright coloured rainbows and this has no comparison to anti-aliasing on a computer. On a foveon sensor however since each photosite effectively records in RGB just like a single computer pixel it suffers from the same problems that spatial anti-aliasing on a computer attempt to fix. Mind you things have gotten much better with recent image samples from the X3 but the early foveon sensor suffered greatly from details which appeared to drift in and out of visibility. The end result may be a technically perfectly sharp image but one with details which look quite strange when blown up, like a computer game running without anti-aliasing.

 

[CCericola]

I've always thought of the Foveon as the Betamax of sensors.

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[unpopular]

^^ high quality and expensive. seems about right. I think that Foveon Inc. sold the technology to the wrong company.

Though I am sure that Richard Merill's retirement was paid.

 

[Solarflare]

I just had a jaw dropping experience: Sigma DP1 Review: Digital Photography Review

Seems that the whole "Foveon X3 has more resolution" is actually more true than I expected.

The problem remains though that this is a very old test and current Demosaicing Algorithms might do much better (just check out how different Leica and Nikon D60 performed).