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-   -   Is there a way to evaluate/compare CRI? (https://www.dvinfo.net/forum/photon-management/482337-there-way-evaluate-compare-cri.html)

Paul Cascio July 24th, 2010 07:49 AM
Is there a way to evaluate/compare CRI?
 
I'm wondering if there is a chart or something that I can shoot, that will let me compare, or perhaps even measure, the relative CRI of different lights. How would I see the difference? Will scopes help?

CRI seems to be this mysterious thing that we can't measure and have to take the word of the manufacturer, which isn't always accurate.

Mark Wheeler July 24th, 2010 08:01 AM
Hmmm... excellent question. I do know that CRI was being reworked to provide LED emitters with a higher rating, which... frankly... smacks a little more of politics then physics.

Per Wikipedia...

Quote:
...according to (Schanda & Sándor 2005), CRI is being deprecated in favor of measures based on color appearance models, such as CIECAM02 and, for daylight simulators, the CIE Metamerism Index. (Guo & Houser 2004) and (CIE 1995) note that CRI is not a good indicator for use in visual assessment, especially for sources below 5000 kelvin (K).
A newer version of the CRI has been developed (R96a), but it has not replaced the better-known Ra (general color rendering index).
For myself, as long as I don't have to deal with sodium vapor lights I'm good.

Giroud Francois July 24th, 2010 10:37 AM
you simply use a color chart, and check that all color are rendered with satisfaction.
with a bad CRI, you will get some colors looking good and some really off.

Bob Grant July 25th, 2010 06:17 AM
Quote:
Originally Posted by Mark Wheeler (Post 1551652)
Hmmm... excellent question. I do know that CRI was being reworked to provide LED emitters with a higher rating, which... frankly... smacks a little more of politics then physics.

Per Wikipedia...



For myself, as long as I don't have to deal with sodium vapor lights I'm good.
Actually it's more physics than politics. This subject was discussed here some time ago. The reason to move to a more advanced system than CRI is because CRI is not a good indicator of color accuracy especially with modern light sources such as LEDs.

Quote:
(Ohno 2006) and others have criticised CRI for not always correlating well with subjective color rendering quality in practice, particularly for light sources with spiky emission spectra such as fluorescent lamps or white LEDs.


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