skip to main content


Title: Development of the IES method for evaluating the color rendition of light sources

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 (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 R f is an improved version of the CIE color rendering index. The color gamut score R g is an improved version of the Gamut Area Index. In combination, they provide two complementary assessments to guide the optimization of future light sources. This method summarizes the findings of the Color Metric Task Group of the Illuminating Engineering Society of North America (IES). It is adopted in the upcoming IES TM-30-2015, and is proposed for consideration with the International Commission on Illumination (CIE).
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ;  [6] ;  [3] ;  [7]
  1. Soraa Inc., Fremont CA (United States)
  2. Cree Inc., Goleta, CA (United States)
  3. Dept. of Architectural Engineering, Penn State University, State College, PA (United States)
  4. National Institute of Standards and Technology, Gaithersburg, MD (United States)
  5. Pacific Northwest National Laboratory
  6. Light&Lighting Laboratory/ESAT, KU Leuven, 3000 Ghent, Belgium
  7. Department of Physics and Astronomy, University of British Columbia, Vancouver Canada
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Optics Express
Additional Journal Information:
Journal Volume: 23; Journal Issue: 12; Journal ID: ISSN 1094-4087
Optical Society of America (OSA)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier: