Color Rendering Index (CRI)
In this installment of EagleLight's LED University we will discuss CRI or the color rendering index.LED CRI Defined
The Color Rendering Index (CRI) is the relative ability of a light source to replicate colors generated by a reference light source of the same color temperature. It is measured as a number between 0 and 100.LED CRI Explained
This is often used to compare a light source ability to replicate the sun. In this case the sun is the reference light source. In layman's terms a CRI of 80 means that the LED light bulb is replicating 80% of the visible color spectrum that the sun would produce at the same color temperature. A CRI of 100%, taken at a color temperature of noon day sunlight will exactly reproduce the colors found on a sunny day at noon. A CRI of 50% taken at noon day sun will partially reproduce the colors when compared to that of a normal noon day.
If you have ever watched a sunset you will notice how the colors change from a purer white to more yellow and red. This color change is typical of the changes in color temperature from higher numbers to lower numbers. If the reference light source used for CRI is at noon day sun a 100% CRI will result in a whiter light, if the reference source used is at sun set, at 100%CRI wil result in a light with more yellow and red. If you were to measure the light of sunset to a reference of noon day sun, the sunset light would only produce a CRI of 60% or less: less than 60% of the light spectrum of noon day light is present in the light of a sunset, hence the shift to more yellows and reds.
Examples of Color Temperature and CRI
Watch the fine print
Some marketers use differing color temperatures as a reference to attain 100% CRI, when the actual CRI would be much less than 100% if noon day sun light was used as a reference.
