Towards the definition of new visual color quality representations

Luminous efficacy of radiation (LER) is one of the multiplicative factors affecting the wall‐plug efficiency of a light source. In order to maximize it, it is important to keep the spectral content of the lamp in a small region around 555 nm. However, doing so limits the color span that the source can correctly reproduce. Obviously, whether one determines to prioritize energy efficiency over color reproduction depends ultimately upon the particular application under consideration. Thus, it is important both to understand theoretically the functional relationship between these inversely correlated variables (design) and at the same time being able to control and tune it in real lighting devices (implementation). The simple computational example shown in Figure 1 serves as an illustration of the expected functional dependence, where the efficacy and general CRI (Ra) are plotted for a family of Gaussian spectra with standard deviations ranging from 10 to 200 nm.