Human perceptions of colour rendition at different chromaticities

Abstract

An experiment was conducted to evaluate how perceptions of a light source’s colour quality depend upon colour rendition and chromaticity. Thirty-four participants each evaluated 50 lighting scenes in a 3.7 m by 5.5 m room filled with objects. The lighting scenes included five chromaticity groups, with 10 systematically-varied colour rendition conditions repeated in each group. Participants, who chromatically adapted to each chromaticity group, were asked to rate each scene on eight point scales for saturated-dull, normal-shifted and like–dislike (preference), as well as choosing whether they found the scenes to be acceptable or unacceptable. The findings suggest that colour rendition perceptions can vary with chromaticity, with an interactive effect of correlated colour temperature and Duv. The same IES TM-30-15 measures, Fidelity Index (IES Rf), Gamut Index (IES Rg) and hue-angle bin 16 (Red) Local Chroma Shift (IES Rcs,h16), could be used to effectively model perceptions within each chromaticity group, and provided suitable performance for the overall set of 50 conditions. The differences in ratings between the chromaticity groups were substantially smaller than the range in ratings for the 10 colour rendition conditions within each group, allowing the same acceptability-based criteria of IES Rf ≥ 75, IES Rg ≥ 98 and −7% ≤ IES Rcs,h16 ≤ 15% to be applied to all chromaticity groups.