When chosing the right lighting for your home, there are a lot of things to consider. Of course, energy efficiency and how many hours of use you'll get is important, checking the CRI scale can also help to ensure that your environment is brighter, clearer and filled with perfect color.
Color Rendering Index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. Light sources with a high CRI are desirable in color-critical applications such as art restoration.
It is defined by the International Commission on Illumination (CIE) as follows:
“Effect of an illuminant on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant.”
Color Rendering Index is determined by the distinctions in the chromaticities of fifteen test color samples (TCS), where objects are illuminated by the light source to be evaluated and a reference illuminant with the same CCT. The lower CRI value, the smaller the differences between indices will be. A CRI value of 100 indicates the best performance of a light source, while a low CRI value may result in some colors looking unnatural. The most commonly used value of CRI is called (Ra), which is the average value of the first eight indices (R1-R8). Lesser-known but more accurate is the Extended CRI (Re), which uses the average value of (R1-R15) and thus serves as a more accurate measure of color fidelity given that it takes the rendering of more colors into account.
This rating is also a measurement in the lighting industry to help discern naturalness, hue discrimination, vividness, preference, color naming accuracy, and color harmony:
- Lights with a CRI that is measured greater than 80 are considered to be more than acceptable for most applications.
- Lights with a CRI that is measured greater than 90 is generally considered “High CRI” lights.