What is the CRI of LEDs?

The feeling here, and I think I agree with it, is that the relatively white light put out by LEDs allows you to see colors better than incandescent flashlights. My wife feels that she can see better with incandescent lights, even when looking at a scene that is more brightly illuminated by one of my LEDs. My reaction has been "that's an illusion created by your familiarity with incandescent beams". But now I'm wondering. 120 volt incandescent light bulbs are a lot more yellow/red than fluorescent lights, yet carry a higher color rendering index (CRI). The incans put out a better spread of the visible wavelengths despite being heavy in the cool end of the spectrum.

I can find CRI figures for all sort of light sources on the Internet, but haven't turned one up for LEDs. Does anyone have a professionally & objectively prepared CRI for these lights?

Thanks in advance!

Nichia says the CRI of their white LEDs is 85, but I don't know what rank these lamps are. I think they were rank BS (color rank B, brightness rank S) but I'm not 100% certain.

Speculation

Thanks for the CRI info. I've done some more comparisons, and find the CRI of 85 for LEDs credible. Incandescents seem to be rated at 100. Evidently one of the few things incandescent bulbs, when compared to LEDs, have going for them is color differentiation.

Does color differentiation play a part in depth perception? If so, I am led to some speculation. If lower CRI values lead to poorer color differentiation and depth perception...would there be more risk of accidents when driving cars with HID headlights?

Take care.

Re: CRI

"professionally & objectively prepared CRI"

If only it were so.
Cri ratings should be taken with several pounds of salt. Or so I was told in a seminar I took on light and color a couple of years ago. There is no scientific test for CRI based on something like distribution of wavelengths included in the output of the source in question. The CRI rating is developed by the manufacturer of the light source, usually by lighting some color samples with a few known sources in comparison with the source in question and inviting anyone they want (employees, friends, folks off the street) to to come in and rate the source. No potential conflict of interest there.

How well a light source renders color will depend on the surface you are looking at and what wavelengths the surface will reflect and the extent to which those wavelengths are present in the output of the source. A given source may do a good job rendering some colors and a poor job with others. And color rendering without full spectrum light can get very complicated very fast. Is a given green car perceived as green because it is reflecting the green wavelengths or the yellow and blue wavelengths?

An incandescent lamp is a black body radiator, and as such, is a full spectrum source (i.e., there is output all across the spectrum). The color temperature (2800-3200K) is low compared to sunlight (5400K)which explains the low output in the blue end of the spectrum. White LEDs, HID lamps, flourescent lamps, etc., are not full spectrum light sources. They are "missing" some wavelenghts in their output. Your eyes are tricked into thinking the output is "white" because of how our eyes work. But if you are looking at something that refects mostly wavelengths that the led or phospher isn't producing, the color won't look right. If the LED manufacturers could make a more complicated phospher blend, they could fill in some of the missing parts of the spectrum and have an LED version of those "kitchen/bath" flourescent lights that do a better job of color rendering.

I don't know if lack of full spectrum light would effect depth perception though. If it did, you would think cities with Sodium vapor street lights would have noticed an increase in accidents.

Re: CRI

Lets boil it down... _____ is in the eye of the beholder. /ubbthreads/images/graemlins/wink.gif