Museum lighting environments are carefully controlled so as not to cause any damage or deterioration to artwork. However, no method currently exists for calculating the change in color rendering properties when illuminance is changed.
The purposes of this study were to clarify color rendering properties at low illuminance and to develop a new method for calculating color rendering values while taking illuminance in to account. The results showed that subjective color feelings of color samples were influenced by illuminance as well as by hue in the samples, especially by red. We defined“color quality indices”called Rx and Rxi to evaluate the new color rendering properties expressing illuminance effects and hue effects. The new indices Rx and Rxi were found to correlate significantly with the subjective results.