Investigation of Colour Naturalness in Lighting: A Comparative Study

This paper is concerned with improving the acceptability of LED light sources, since their long life and high efficiency have contributed to their widespread adoption in many applications. Concerns remain, however, in relation to their colour properties. The purpose of this paper is therefore to promote discussion of the naturalness concept among the users, specifiers, and manufacturers of lighting sources and systems, in the hope that this may provide a valid pathway to the classification of light-source colour properties. An overview is presented of experimental investigations aimed at establishing visually meaningful metrics for the colour quality of various light sources, predominantly LEDs. All the cases presented here included colour naturalness as at least one of the dimensions studied, and one has to conclude that naturalness is a property of great interest to lighting engineers and scientists. Because the majority of naturalness studies have invoked the use of pre-existing colour quality metrics, the paper also includes an overview of some of the major such metrics and their features. The paper also identifies two important concerns relating to Naturalness: the need to agree on an acceptable definition of colour naturalness in lighting; and how to standardize or compare the results of disparate investigations. Finally, the paper proposes the concept of a colour fidelity continuum, in the ultimate hope of uniting the various approaches to lighting colour quality. Doi: 10.28991/HEF-2022-03-02-04 Full Text: PDF