Human Perceptions of Colour Rendition at Different Chromaticities
- BATTELLE (PACIFIC NW LAB)
- Hong Kong University of Science and Technology
An experiment was conducted to evaluate how subjective impressions of a light source’s color quality depend upon color rendition and chromaticity. Thirty-three participants each evaluated 50 lighting scenes in a 3.7 m by 5.5 m room filled with objects selected to cover a range of hue, saturation, and lightness. The lighting scenes included five chromaticity groups, specified here using correlated color temperature (CCT) and Duv¬: 2700 K, 0.000; 2700 K, -0.007; 3500 K, 0.000; 4300 K, 0.000; 4300 K, -0.007. Within each group were the same 10 systematically-varied color rendition conditions. The Illuminating Engineering Society (IES) TM-30-15 Fidelity Index (Rf) values ranged from 60 to 93, IES TM-30 Gamut Index (Rg) values from 88 to 124, and IES TM-30 Hue Angle Bin 1 Chroma Shift (Rcs,h1) values from -15% to 28%. All lighting scenes had the same nominal illuminance. Participants were asked to rate each scene on eight point scales for saturated-dull, normal-shifted, and like-dislike, as well as choosing whether they found the scenes to be acceptable or unacceptable. The findings suggest that color rendition preferences can vary with chromaticity, but do not support absolute preferences for negative Duv values. At 4300 K, there was no difference in rated preference, saturation, normalness, or acceptability between the two groups with different Duv values. However, at 2700 K, there was a significant difference for all four perceptions, with the negative Duv sources being rated more liked (on average)—and for nine of the ten individual color rendition conditions. Further, across all levels of red chroma shift—according to TM-30 values Rcs,h1, Rcs,h15, and Rcs,h16—the room was rated as more saturated at 2700 K than at 3500 K or 4300 K (regardless of Duv); in turn, increases in red saturation were less preferred and less acceptable at 2700 K than the other CCTs. The differences in ratings between the chromaticity groups were substantially smaller than the range in ratings for the 10 color rendition conditions in each group, and on average the best fit model uses a combination of Rf, Rcs,h16, and potentially Rg. Despite the differences in ratings for chromaticity groups, a set of criteria identified in previous research for preferred color rendition in this generic application could be used for all groups. Those criteria are Rf = 74, -1% = Rcs,h1 = 15%, and Rg = 100.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1558186
- Report Number(s):
- PNNL-SA-125201
- Journal Information:
- Lighting Research and Technology, Vol. 50, Issue 7
- Country of Publication:
- United States
- Language:
- English
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