Psychophysical optimization of lighting spectra for naturalness, preference, and chromatic diversity.

The optimal spectral profiles of lighting for naturalness, individual preference, and chromatic diversity were estimated with psychophysical experiments in which observers selected illuminants from a set of metamers of D65 to render outdoor and indoor scenes. For naturalness, the illuminant selected was more spectrally structured than daylight and had a low color rendering index. For preference, the illuminant was similar but produced colors a little more saturated. For chromatic diversity, the spectrum was much more structured, with clearly defined peaks in the blue, green, and red spectral regions. These experiments show that light sources with specific structured spectra may have important visual applications in lighting.