Hmm... of the ones they listed, I suspect the color rendering will be as follows, highest first:
- Blue + Red and Green Phoshphor/UV + RGB phosphors -- premium fluorescent lamps, ones that have 90CRI are triphosphor, and color temperature is controlled by adjusted the relative amounts of each phosphor used. However, a Blue + biphosphor shoudl be close to the same thing
- Blue + Yellow Phosphor (what we are used to) -- these can have huge variations though, good LEDs such as the "warmer" Cree LEDs tend to have very broad spectrum phosphor emissions and actually look quite good. These are more similar to standard "cool white" fluorescent for color output.
- RGB separate Emitters -- these can have problems with fringing, where the beam is not mixed adequately and shadows are cast showing the separate red, green and blue components. These would be best for use as pixels, or accent lights with user adjustable color temperature -- in a flashlight that might be useful as for some jobs warm white may provide better contrast in some applications, and cool white in others. Also, monochromatic light could be achieved by turning off two of the three emitters (ie if red was needed to preserve night vision)
- YB separate emitters -- under these it will be impossible to perceive anything that is predominately green -- grass will look black, and red will be just as bad, or worse, as with a blue plus phosphor combination. This would probaly render color as badly as high pressure sodium lamps.
A few other ideas I think would work would be:
Blue + Phosphor (typical white LED) + separate Red Emitter -- red is usually the only deficiency in a good LED, if you could solve the mixing problem, this would be an almost ideal light source.
A couple other things about CRI -- this unit itself isn't very useful in my opinion. It's a measurement of how closely a lamp matches a blackbody radiator of the same color temperature. Unfiltered incandescent is by definition 100 as it is a blackbody radiator. The metric was designed mainly to describe old cool white fluorescent tubes that used broad spectrum phosphors. It can't be used to directly compare lights of different color temperatures -- this is why lights in the 3500-5000K color temp range generally look better than lights with the same CRI outside that range. (In the case of incandescent, 3500 is about the hottest they can go -- the hotwire bulbs used in incan mods on these boards render color better than a typical 2700k house lamp, both at CRI 100)
Finally, lights with the same CRI number might be vastly different -- for example, one lamp with 70CRI may make color look more vivid and saturated, another may make things look dull and sickly, but as both vary from blackbody by the same amount, they get the same CRI number.
