My contribution to the April issue of ELECTRICAL CONTRACTOR presents TM-30, the proposed method for evaluating color rendering and saturation, and describes a recent study that suggests saturation is critical to truly evaluating color quality. Specific gamut shapes may be critical to modeling human color preference.

The study found that Rf is a good predictor for how normal colors appear, while Rg is a good predictor for perception of saturation. Neither alone, however, proved a good predictor of preference. This means that, even if two light sources have the same Rf and Rg values, they can result in very different subjective impressions. Participants showed a distinct preference for saturated reds. This indicates specific gamut shapes are more important than Rf and Rg in modeling preference.

Interestingly, a majority of the most favored sources had CRI values below 73, a range normally considered fair or poor in color rendering. The CRI metric significantly penalizes increases in red saturation, which results in light sources engineered to achieve a certain CRI but with less-preferred gamut shapes. Most energy-efficient lighting available today does not saturate reds.

Check out the full story here.