De-entangling colorfulness and fidelity for a complete statistical description of color quality.

In this Letter, the main attributes known to affect color quality are treated statistically over a set of 118 spectra representing the current mainstream lighting technology. The color rendering index (CRI) is used to assess color fidelity while colorfulness is used to complement CRI-R(a), supported by the growing evidence that assessment of light spectra cannot overlook color preference inputs. Colorfulness is evaluated by our optimal color (O(c)) index, through a code that computes the (MacAdam) theoretical maximum volumetric gamut of objects under a given illuminant for all the spectra in our database. Pearson correlation coefficients for CRI-R(a), the (Y. Ohno's) color quality scale (CQS) and O(c) show a high correlation (0.950) between CRI-R(a) and CQS-Q(a), while O(c) shows the lowest correlation (0.577) with CRI-R(a), meaning that O(c) represents the best complement to CRI-R(a) and Q(a) for an in-depth study of color quality.