What is "Foveon Blue"?

Mark Scott Abeln wrote:

xpatUSA wrote:

Pardon me, but I'm getting slightly grumpy. I'm shot down in flames on sky shots, lamp shots and no doubt the circling sharks are still thinking about watch hands and lamp spectra (a great silence there, though), while all I seek is the Great Universal Truth. What is the correct white balance for light sources?

OK, it appears that the eye processes self-luminous objects differently than illuminated scenes.

Astronomers, who often are interested in capturing visually accurate colors of the self luminous stars, will use a daylight white balance. Note that this will render the sky itself an ugly brown color (which is due mainly but not exclusively to man-made light pollution), and so often they will color correct the sky separately from the star colors (tungsten white balance is often more pleasing for the sky color itself at night) Also, they will often use a very broad color space, since many of the colors they capture are spectral. Note that daylight balance (depending on the camera) is fairly close to the standard E illuminant — at least is close enough for government work.

Note that this result will be for small, bright light sources with a dark surround. If adjacent surface colors get brighter, the normal white balance effects will take over.

Good. Looks like we're on the same page. SD9 shot, sunlight WB (5400K on SD9) adjusted to 5455K (E) and -13 per the DNG SDK:

Although illuminated by a small UV lamp at some distance, the hand fluorescence dominates.

Alternatively could have shot in the dark but the SD9 is not good on long exposures.

Please note that color temperature and tint readings for any given model of camera (such as found in Adobe Camera Raw) are reversed-engineered from measured color response, and so will vary considerably between models.

Iliah tells me that the tint reading relative to a Luv distance is specified as times 3000 exactly in the DNG SDK. So for a SD9 and ACR, I'm fairly happy. I do know from the RawDigger manual that the color temperatures themselves for different camera models' settings are quite variable. And yes, even if a camera itself has a temp/tint WB setting option, the tint part is usually unspecified whereas a K is a K, eh?