Observer preference for perceived illumination chromaticity

Subjects assessed white tone preference and tint percentage perception (e.g., a faint greenish tint perceived in the white tone) in a viewing booth containing small colored objects at the illuminance level of 1000 lx for cool white, neutral white and warm white spectra. White points with the lowest perceived tint percentage were most preferred. White tone preference was rated on interval scales labeled by semantic categories, for example, “very good,” “good,” and “moderate” The location of the white points of different preference levels (e.g., “good‐very good” level or “moderate‐good” level) was depicted in the u′‐v′ chromaticity diagram. The most preferred white points were located below the Planckian locus, inside the region of the white points required by CIE Publication 13.3 (1995) with the criterion of the chromaticity difference DC being <0.0054. The most preferred correlated color temperature (CCT) was at 3400, 4500, and 5800 K in the warm, neutral, and cool white CCT groups, respectively. Results were interpreted in terms of the Rea and Freyssinier (2014) model.