Whiteness and preference perception of white light sources: A case study at 5500 K with positive and negative Duv values

Recent studies reported a series of neutral loci for white lighting, which showed significant differences when the correlated colour temperature was greater than 4000 K. Several were located above the Planckian locus while others were located below. In addition, some researchers indicated that the whiteness of lighting correlates with colour preference (i.e. visual appreciation on the colour rendition of lighting) but that conclusion is not in full accordance with certain individual results of preference or whiteness evaluation. To investigate the perceived whiteness and colour preference in a viewing cabinet, two visual experiments were carried out. The light sources adopted in both the experiments were eight sources of 5500 K, that included four with constant positive Duv values (similar to 0.004) and four having constant negative Duv values (similar to - 0.006). The illuminance levels were approximately 200 lux while the Color Rendering Index (CRI) values were in range of 85-91. The results showed that sources of negative Duvs obtained higher values of whiteness assessment and their colour rendition was preferred by observers. The findings also strengthen the opinion that, for practical conditions with a constant CCT and acceptable CRI values, the Duv value could be considered as an effective indicator for colour preference judgement.

Automated summary

Recent studies have identified differences in neutral loci for white lighting with correlated colour temperatures above 4000K. The Duv value could be considered as an effective indicator for color preference judgement under certain practical conditions.