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| p.3 #9 · DxOMark is out - Nikon D800 new king |
At the levels we're discussing this, it's mostly academic. A metameric failure can affect either hue, saturation or brightness - or any combination of the three.
It actually makes more difference how you build the camera color profile, and how the color profile affects the noise reduction algorithms in the raw converter. A more dense (more peaky, more discriminating) color filter array isn't necessarily good in all situations. If you look at medium format formulations, they're typically just CRAP if you use them in fluorescent lights. Totally impossible to correct.
You have to weigh color noise against color accuracy against color discrimination. There is no "correct" solution.
Trying to mimic the human eye exactly is quite useless in a real camera. I know a few multispectral solutions that can do this, but they're only useful in very good light at base ISO. The M and L cones in the eye are really to tightly spaced in wavelength sensitivity to give good color discrimination, but your brain makes up for this with some really heavy processing over both angle and time (humans don't see in still images, we see "shape in continuous video"). If we tried to mimic that in a camera the color noise already at ISO800 would be horrible, and affect the color accuracy way, way more than a small amount of metamerical failures.
As long as you can go from camera raw ADU to standardized XYZ in a reasonably linear way, and the filters are good natured (no double peaks, smooth and few - preferably only three - derivate nulls on the wavelength sensitivity) you can get color that's "good enough".
The black magic is in finding a filter formulation that works well and easy with the type of calibration that you use. Sony had a good thing going with the A900/850, that seemed to hit a sweetspot regarding this, even though they weren't any measurably better than many other examples.
Canon has chosen a more "human-like" filtration, that gives them their trademark magenta/green color noise, and good resistance to brightness variations in skintones in difficult lighting. This does sacrifice color accuracy and hue discrimination though. Canons are notoriously hard to get "just right" in the more saturated yellow-orange part of the spectrum.