Does Color Rendering Matter? 2

Examine CRI R9

We have referenced the R9 values for the 80, 90, and 95 CRI color quality levels. While there is no definitive formula, a significant link exists between the CRI value and the R9 value, which approximately align at 25, 50, and 90 for CRI values of 80, 90, and 95, respectively.
CRI is a comprehensive metric that assesses the accuracy of a light source, whereas R9 is a specific metric that evaluates its capacity to render red hues. As previously said, red hues are among the most common in several things and materials; thus, employing R9 as an adjunct to CRI is an effective method for assessing a light source.
The most prominent distinctions between 50 and 90 R9 values are evident in skin tones. If you are engaged in photography, you will likely perceive the change instantaneously.

The Significance of CRI Values

CRI is the predominant metric for assessing color rendering, with a maximum score of 100. Although it may seem alluring to assign a percentage or letter grade to the CRI values, the figures are somewhat arbitrarily derived from color difference values. We advise against asserting that "80 CRI indicates the light source is 80% accurate," as this misrepresents the calculation of CRI.
The Color Rendering Index (CRI) is determined by assessing the reflected colors from a set of eight standardized hues, known as test color samples (TCS), and contrasting them with the colors reflected by a reference light source, such as natural daylight. In other words, it inquires: on average, how distinct do these eight color swatches appear in comparison to a natural light source?
The color discrepancies are quantified numerically, and the mean difference is subsequently removed from 100 to ascertain the final CRI rating. Consequently, one may consider the disparity between the CRI value and 100 as its "difference score." For instance, a CRI of 95 corresponds to an average color difference of 5, whereas a CRI of 80 reflects an average color difference of 20.
What is the importance of this? Initially, it provides an alternative perspective on CRI ratings and their corresponding levels of color fidelity by examining the deviation from 100. A 95 CRI light source exhibits a difference of 5.0, whereas a 90 CRI light source demonstrates a difference comparable to twice its magnitude, and an 80 CRI light source corresponds to four times its magnitude.

Concluding Reflections

We have conveyed our insights from our experience and lighting knowledge, and we hope to have illuminated the complex subject of color rendering. Ultimately, the suitability of a specific level of color rendering for a given area is contingent upon its impact on the individuals utilizing the light or inhabiting the space. High CRI LED lighting entails a greater initial investment and reduced efficiency, which should be seen as disadvantages when enhancing the color rendering of an environment.