Subjective preferences and colour quality metrics of LED light sources

Abstract

To understand people's judgement of the naturalness of object colours and preference for the lit environment, lighting booth experiments were conducted. Seven different LED spectral power distributions, all at correlated colour temperatures of 2700 K, 4000 K and 6500 K, were simulated for high CIE colour rendering index (Ra), high colour quality scale (CQS) colour preference scale (Qp) keeping Ra ¼ 80, high feeling of contrast index (FCI) keeping Ra ¼ 80, high CQS relative gamut area scale (Qg) keeping Ra ¼ 80, low FCI keeping Ra ¼ 80, low Qp keeping Ra ¼ 80, and for a mimic of a fluorescent lamp (FL) in terms of the closest possible value of the Ra, FCI and Qp to the reference FL. Other metrics such as the gamut area index (GAI), memory CRI, and nCRI were also considered in the analysis. Sixty observers evaluated 24 lighting situations. This paper deals with a comparison evaluation, where LED lighting was compared to FL lighting. It was found that Ra does not explain the subjective naturalness of objects and the subjective preference of the lit environment for the different light sources. The results also indicate that people's judgement of naturalness and overall preference were explained better when a reference-based metric (such as Qp) and an area or volume-based metric (such as Qg or GAI) were both considered while maintaining the light source chromaticity difference (Duv) value within the limit AE 0.0054.

Energy and economic benefits of LED adoption in Malaysia

“…Another technique uses more than three different colored LEDs (red, green, blue) to produce white light [35]. Increasing the component color will result in better spectral and color rendering properties.…”

Co‐precipitation synthesis and luminescence properties of K2TiF6:Mn4+ red phosphors for warm white light‐emitting diodes

“…Therefore, more potential colour expressions can be reflected from materials in the environment. Generally, if the CRI value of a light source is > 80, the light source is suitable for indoor lighting . Therefore, it may be regarded as a potential candidate for a red‐emitting phosphor in converting blue LED light.…”

Effect of Window Glazing on Colour Quality of Transmitted Daylight

“…their chromaticity coordinates lie above the black body curve. Theoretically, this transmitted light will not be preferred by the user, as Dangol et al [31] and Islam et al [32] found that the observer preferred LED SPDs (spectral power distribution) with D uv values of the light sources were either negative or close to the black body locus. D uv values of light sources affect subjective preference.…”

“…Moreover, from the studies [31][32][33][34], it was clear that R9 is not an indicator of subjective preference. However, the chroma and colourfulness values of object colours calculated using CAM02-UCS have a great influence on the subjective preferences, especially for the naturalness and colourfulness (subjective measure).…”