A New Way to Understand the Color Rendition Performance of Multi-Primary LED Lighting Systems: Color Rendition Variability (CRV)

Tunable, multi-primary LED systems offer the potential for easily customizable lighting solutions, particularly for color quality and other spectrally derived performance characteristics. However, testing and comparing the performance of these systems is substantially more complicated than for fixed-output lighting products. This article reports on the development of a measure for characterizing the range of variation in color rendition that is possible for a tunable, multi-primary LED system–a characteristic deemed color rendition variability (CRV). The proposed CRV metric is derived from the set of metameric SPDs that can be created for a given product (real or theoretical) based on the measurements of individual LED primaries. It is a tool that provides composite information about the flexibility of the system that goes beyond minimum and maximum values for individual measures of color rendition, such as ANSI/IES TM-30 R_f, R_g, and R_cs,h1. The utility and face validity of CRV were evaluated using combinations that could be produced for 132 unique, theoretical multi-primary LED systems. The theoretical systems had four, five, six or seven LED primaries, each chosen from a set of 32 options. Thirty-three combinations of each size were established; three targeted selections mimicking typical combinations of LED primaries, and 30 random combinations. The results demonstrate how CRV can provide value as one of the many characteristics that might be optimized when developing a tunable lighting system.