# Color Rendering Index of various LED's



## z_projectdp (Jan 26, 2011)

I have seen the McGizmo Sundrop, and the HDS High CRI - http://www.hdslights.com/?id=ClickyHighCri lights.



I was curious what LED's these use to achieve a high rating, which seems to be the case on the Sundrop, and is stated as a 93 CRI rating for the HDS.



Further, are there other Lights, not just LED's that tout a high CRI?



Are there similarly performing lights that you are aware of? I understand the CRI to mean that lights with a high CRI rating are produce similar colorization as that in daylight. This should be due to the fact that a maximum rating corresponds to the complete range of the colors in the visible spectrum.



Am I off base with my approach to this topic?



I'm entirely new to this. I lurked on edcforums for several years before arriving here, though I've seen you linked plenty there.



Thanks yall!


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## Quigath (May 20, 2011)

z_projectdp said:


> I was curious what LED's these use to achieve a high rating, which seems to be the case on the Sundrop, and is stated as a 93 CRI rating for the HDS.


From what I know the Sundrop uses a Nichia 083, but they are only sold in >1000 quantities.




z_projectdp said:


> Further, are there other Lights, not just LED's that tout a high CRI?


This is a tricky question because of the definition of CRI: it is how closely a light spectrum resembles a blackbody curve. By that definition all incandescent lights are 100CRI as well as the sun at noon. When talking about the quality of light with high CRI, you also need to account for the CCT, or temperature, of the light source.




z_projectdp said:


> This should be due to the fact that a maximum rating corresponds to the complete range of the colors in the visible spectrum.
> 
> Am I off base with my approach to this topic?


Your eye is more sensitive to some wavelengths of light than others, your eye was made to be sensitive to daylight, so matching CRI will give your eye what it is most sensitive to in normal conditions.

As for color temperature, you need to factor in what the application will be and desired practical outputs. For example, at nights warmer color temp is more pleasing but at midday sunlight can appear cooler. Also, most LEDs are brighter at cooler CCT as the phosphors needed to make warmer color reduce total light output.


I'm new to high CRI also but have gleaned this much from the forums so far.


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## HooNz (May 22, 2011)

[QUOTE= your eye was made to be sensitive to daylight [QUOTE

I have a complaint to the management , the Macula is coloured yellow people guess to filter out Uv and the Blue wavelength , my complaint is i would like to go al-la-natural to see all the bits that are missing as being a suspicious one i seem to suspise that something is being hidden!


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## blasterman (May 22, 2011)

Be aware that the current standards for CRI ratings are old, and overly generous. They also don't correspond to how even the spectrum of the light source is but typically how well specific reflective (low gamut *cough* ) color patches are illuminated. For instance, many light sources are rated in the mid 90's for CRI but incapable of emitting light more red than 620nm (orangish red). 

With LEDs the basic difference between normal and high CRI versions is the amber component. With an increase in the amber component blue and green gets dropped a bit to even out. This tends to crush efficiency, but pumps up even color rendition.

IMHO, LEDs above 80 CRI all look pretty good and are visually outstanding at 90CRI.


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## Opto-King (May 31, 2011)

Hi,
FYI, CRI values shown on products are normally only showing R1-R8 and missing out on the R9 (deep red). if you look at this link: http://www.optodrive.se/Colour_Rendering_Index.pab you can get a better understanding of what I mean. However, as you can alos see on the same web page there are LED solutions showing High CRI (e.g. 93) with R9 value included.


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## HooNz (Jun 1, 2011)

I had a look at the link Opto-King , what a crackup , i wonder who or what wrote it?

copy/pasted -"that the humans" , and another reference to "as those humans" , not 'us' or 'we' etcetera , LOL.

Human = Hue Man , a shade of ! , not real , compared to them! imo :huh:


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## Bullzeyebill (Jun 1, 2011)

HooNx, this looks like a translation issue. Not a good one, no doubt. Need to read the original language version for accuracy.

Bill


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## HooNz (Jun 1, 2011)

Bullzeyebill said:


> HooNx, this looks like a translation issue. Bill



I did translate it :sigh:

It's everywhere


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## Opto-King (Jun 1, 2011)

Hi,
Sure the spelling is not correct but the information is (and I beleve that it is what counts)... or did you find anything in the information that is not correct? Please help me with this since I will use this info for a school project.

Thanks!


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## HooNz (Jun 1, 2011)

Opto-King said:


> Hi,
> Sure the spelling is not correct but the information is (and I beleve that it is what counts)... or did you find anything in the information that is not correct? Please help me with this since I will use this info for a school project.
> 
> Thanks!


 
@ me? , so just in case , the information seemed correct not that i'm a expert , but at a guess looks ok! .

apart from the meaning of human though :laughing:


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## qwertyydude (Jun 2, 2011)

Movie studio HMI lights average only about 85 CRI so anything around that range will suffice since even at that CRI it looks just like noonday sun. I remember at a mall where I worked a TV show was being filmed. They brought in this giant helium blimp that carried a few of these HMI lights and when they turned it on I could have sworn they cut open the ceiling, it looked just like the mall was lit with sunlight.


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## lyyyghtmaster (Jun 4, 2011)

I agree, the lack of R9 rendering is probably the most serious deficiency in CFL and LED offerings alike, although they could certainly use more aqua as well. CFLs are the worst in not going much beyond 613nm, still very orangey. I have wondered why, with such poor spectral content, most red objects still appear reasonably red. Maybe the eye is adjusting... Whatever it is, warm CFLs don't properly render the blood colors in the skin, causing it to appear pasty, as though one is perpetually wearing makeup (even guys!) yuck!! Ever since I A/B'd a 2700K CCT CFL and an incan I have seen warm CFLs in a new (not good!) light. There is another thread on the lack of hi-CRI warm CFLs here somewhere.

LEDs are better, gracefully dropping off output into the deep red, but even the hi-CRI ones (such as the SSC P4 entry) can't rival sunlight, let alone an incan, for percent of deep red making up the white light.

I have heard a normal-CRI LED (cool or neutral) can be augmented with 660nm deep red and 490-or-so aqua (in suitable small amounts) to fill the biggest holes in the spectral power distribution, improving the color rendition. (as opposed to Color Rendering Index, which as has been noted is based only on the 8 general rendering indices and not any of the special ones.) It probably improves CRI too of course. This might be a way to overcome the lack of deep red in the spectrum of phosphor conversion, although it will still result in a spikey output. And efficiency will drop since deep red is harder to see than orange-red. I vaguely seem to remember a bulb so constructed may have actually been/is being produced?

Hopefully this deep red issue is being strongly investigated as new LED products emerge, since the CFL manufacturers sure dropped that ball pretty badly. :sigh:


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## SemiMan (Jun 7, 2011)

CRI - Is only referenced to sunlight when the colour temperature is above 5000K. Below 5000K, a blackbody radiator is the reference.

As many mentioned, there is R8 which the most common CRI measurement of late, R9 which adds deep red, and there is also R15 which adds in saturated colors.

Semiman


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## jtr1962 (Jun 7, 2011)

lyyyghtmaster said:


> I agree, the lack of R9 rendering is probably the most serious deficiency in CFL and LED offerings alike, although they could certainly use more aqua as well. CFLs are the worst in not going much beyond 613nm, still very orangey. I have wondered why, with such poor spectral content, most red objects still appear reasonably red.


The reason is very little of what we illuminate is deep red, so we can effectively lose that part of the spectrum while still retaining reasonable color rendering.



> Maybe the eye is adjusting... Whatever it is, warm CFLs don't properly render the blood colors in the skin, causing it to appear pasty, as though one is perpetually wearing makeup (even guys!) yuck!! Ever since I A/B'd a 2700K CCT CFL and an incan I have seen warm CFLs in a new (not good!) light. There is another thread on the lack of hi-CRI warm CFLs here somewhere.


The pasty appearance is an artifact of a light source lacking in deer reds trying to imitate a 2700K blackbody. This is why I've been saying it's a bad idea making CFLs, and to a lesser extent LEDs, imitate incandescents. Instead, don't bother with CCTs under 3500K. This is still acceptable to nearly all of the population, and certainly easy to get used to even if you've been living under 2700K incandescent. As you increase CCT, deep red is a smaller part of a black body spectrum, and its absence is less noticeable when using light sources lacking deep red. This is why 3500K and 5000K CFLs don't look as "wrong" as 2700K ones do even though all still lack deep reds. Your eye just doesn't expect as much deep red if the light source is whiter.



> LEDs are better, gracefully dropping off output into the deep red, but even the hi-CRI ones (such as the SSC P4 entry) can't rival sunlight, let alone an incan, for percent of deep red making up the white light.


Honestly, it's more the spectral discontinuities of CFLs that make some of them feel weird than it is the deep red deficiency, although that doesn't help. LEDs, being a continuous spectrum, already feel more natural than flourescent, even if they might come up short over certain wavelengths. Let's not forget the deficiencies on the blue end of incandescent. That to me is a bigger problem than lack of deep red in LEDs/CFLs. If anything, based on what I've seen, LEDs seem closer to natural sunlight than any other artificial source I've used, even if this isn't reflected in the CRI ratings. CRI really just tells us how close a given light source matches a blackbody at a similar color temperature. A red hot heating element and the sun both have a CRI of 100, but would anyone consider the heating element a great light source? Even incandescent falls somewhere in between these two extremes. In the real world, it's not as good as the 100 CRI statistic says it is. This is why the CQS (color quality scale) is being developed. It will more accurately reflect the acceptability of a light source than CRI.


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## lyyyghtmaster (Jun 8, 2011)

jtr1962,
I pretty much agree with what you said. There might have been a slight misunderstanding when you said:



jtr1962 said:


> The reason is very little of what we illuminate is deep red, so we can effectively lose that part of the spectrum while still retaining reasonable color rendering.



I guess I wasn't clear enough in my statement. I'm not referring to those few pigments that are actually mostly deep red. What I meant is that even shallow red objects look deeper red under a 82-CRI CFL than you would expect them to given the poor red spectra. I'm thinking the eye accommodates this and makes it look deeper red than the light actually is. A colorful scene looks more normal than would be expected until you try to illuminate an object that really does only have deep red reflectivity in which case the light's deficiencies finally become obvious. I agree it would be a waste in many situations to include deep red in a light source when it's not needed. I just wish they had given us the option! Finally LEDs will hopefully solve all that.




jtr1962 said:


> The pasty appearance is an artifact of a light source lacking in deer reds trying to imitate a 2700K blackbody. This is why I've been saying it's a bad idea making CFLs, and to a lesser extent LEDs, imitate incandescents. Instead, don't bother with CCTs under 3500K. This is still acceptable to nearly all of the population, and certainly easy to get used to even if you've been living under 2700K incandescent. As you increase CCT, deep red is a smaller part of a black body spectrum, and its absence is less noticeable when using light sources lacking deep red. This is why 3500K and 5000K CFLs don't look as "wrong" as 2700K ones do even though all still lack deep reds. Your eye just doesn't expect as much deep red if the light source is whiter.



I thought of this argument after posting but had already shut off the computer.  Yes I do find daylight CFLs much less objectionable than 2700K ones for that very reason. And when I do need the deep red I can use a "full spectrum" CFL for daylight applications.

I have another CFL color gripe. Unfortunately I find many hi-CCT CFLs have a greenish tint. This bugs me so badly that I actually search for daylight CFLs that are less greenish and have created a rough binning scheme for this. Last I checked GE made some pretty good 6500K ones, although even these get greenish if they can't stay cool enough inside a more enclosed fixture or the enclosure glass is thick and green. TCP, when they first started making CFLs, had hi-CCT lamps with a very good color appearance which if anything may have been very slightly on the lavender-tint side of the BBL. They look great even in thick glass fixtures. Unfortunately after a few years they switched to the same ugly puke-green tinted phosphor blend that everyone else uses. I'm guessing manufacturers do this for one or more of these reasons: 1) the orange-red phosphor might be more expensive; 2) green is more visible and results in higher lumen figures; 3) the red phosphor dims more rapidly as the lamp overheats in an enclosed fixture than the other colors thereby hurting perceived lumens; 4) they think the greenish color is more expected/acceptable to users. Whatever it is I hate it! Luckily I have a large stock of original TCP daylight lamps so it's not too big an issue for me. :thumbsup: So far I have not noticed this problem from the LED bulbs I've tried, probably because of some of the things you write in the next section:



jtr1962 said:


> Honestly, it's more the spectral discontinuities of CFLs that make some of them feel weird than it is the deep red deficiency, although that doesn't help. LEDs, being a continuous spectrum, already feel more natural than flourescent, even if they might come up short over certain wavelengths. Let's not forget the deficiencies on the blue end of incandescent. That to me is a bigger problem than lack of deep red in LEDs/CFLs. If anything, based on what I've seen, LEDs seem closer to natural sunlight than any other artificial source I've used, even if this isn't reflected in the CRI ratings. CRI really just tells us how close a given light source matches a blackbody at a similar color temperature. A red hot heating element and the sun both have a CRI of 100, but would anyone consider the heating element a great light source? Even incandescent falls somewhere in between these two extremes. In the real world, it's not as good as the 100 CRI statistic says it is. This is why the CQS (color quality scale) is being developed. It will more accurately reflect the acceptability of a light source than CRI.



I totally agree with that entire paragraph. Yes incan color has its problems. Though possessing a 100 CRI and great R9 capabilities it is deficient in blue. It can easily appear yellowish and it's just way too warm for some apps. Yet it does have one advantage that I have never seen in a single CFL or LED bulb: as you dim it color temp drops. I can see why no CFL does this. When will someone try to make an LED bulb which does that? I miss it very much for mood lighting applications. It would still be too expensive though, requiring some combination of multiple-CCT LEDs and probably red and other color LEDs as well.


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