Metameric Light Sources: A Recent Paradigm for Functional Lighting

Recent progress in tuneable solid-state light sources opens new opportunities in a niche and high added value lighting applications. The standard colorimetric technique of composing an identical colour coordinate metameric light spectra are facing the challenges due to the colour discrepancy noticed by the observers. A side-by-side colour matching experiment was performed with two tuneable tetrachromatic RAGB lamps (638 nm red, 598 nm pc amber, 518 nm green, 451 nm blue LEDs) to compare the colour of the metameres in a 10-deg viewing angle. The metameric light matching was investigated using a 2-deg (CIE 1931) and 10-deg (CIE 1964) XYZ colour matching function. Both colour matching functions of standard colorimetric observers were shown to be inaccurate for aligning of metameric spectral power distributions without a noticeable difference in a perceived colour. On the other hand, a wide scatter of individual results revealed that the standard colour matching functions are inherently limited and in some cases, especially in professional lighting applications, the individually adjustable metameric lighting approach is to be considered.