Optimization of colour quality of LED lighting with reference to memory colours

Simulated and real tri- and tetrachromatic light-emitting-diode (LED) clusters were optimized for luminous efficacy of radiation (LER) and the memory colour quality metric developed by the authors. The simulated clusters showed no significant differences in achievable colour quality and LER between the different cluster types investigated. The real clusters (composed of commercially available LEDs) showed substantial differences in achievable colour quality and LER between the different cluster types investigated. The real clusters also exhibited a large drop in LER and memory colour quality compared to the simulated clusters due to the limited range of available peak wavelengths and spectral halfwidths. A real tetrachromatic LED lamp, constructed with commercial red, green, blue and warm white LEDs, was optimized for LER and colour quality. In a psychophysical experiment, several aspects of the colour quality of the LED lamp (optimized for 2700 K) and an incandescent lamp were assessed by 18 observers. The visual appreciation (in terms of attractiveness, preference, and memory colour similarity) of the LED lamp was rated significantly higher than the incandescent lamp.