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Development of the IES method for evaluating the color rendition of light



Yoshihiro Ohno, Aurelien David, Kevin Houser, Minchen Wei, Michael Royer, Kevin Smet, Lorne Whitehead


We have developed a two-measure system for evaluating light sources’ color rendition that builds upon conceptual progress of numerous researchers over the last two decades. The system quantifies the color fidelity and color gamut (i.e. change in object chroma) of a light source in comparison to a reference illuminant. The calculations are based on a newly developed set of reflectance data from real samples uniformly distributed in color space (thereby fairly representing all colors) and in wavelength space (thereby precluding artificial optimization of the color rendition scores by spectral engineering). The color fidelity score Rf is an improved version of the CIE color rendering index. The color gamut score Rg is an improved version of the Gamut Area Index. In combination,they provide two complementary assessments to guide the optimization of future light sources and allow lighting specifiers to appropriately match sources with applications.
Optics Express


color rendering, color fidelity, color rendition, gamut area


Ohno, Y. , David, A. , Houser, K. , Wei, M. , Royer, M. , Smet, K. and Whitehead, L. (2015), Development of the IES method for evaluating the color rendition of light, Optics Express, [online], (Accessed December 4, 2023)
Created June 30, 2015, Updated November 10, 2018