IES publishes new CRI color rendering index guidelines for light sources
In technical note PS-8-14 entitled Color Rendering Index (CRI), the Illuminating Engineering Society identified the following CRI shortcoming: "The IES recognizes that the Color Rendering Index (CRI) metric, used to determine the accuracy of a light source's rendition of color compared to a reference, has shortcomings that limit its ability to fully represent how humans perceive color. Since its adoption in 1964, several light source technologies have been introduced and commonly adopted for architectural lighting that yield a different visual experience than the CRI metric can describe."
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The IES note continues, "To this end, the Illuminating Engineering Society (IES) formed a Color Metric Task Group in March 2013, which has been tasked to develop an improved measure to characterize light source color rendition. This group is committed to developing an alternative to CRI that will better serve the lighting industry and its stakeholders."
Now, in 2015, the US Department of Energy (DOE) reports that the IES published a technical memorandum, TM-30-15, that outlines a new system for evaluating the color rendition of light sources. While the International Commission on Illumination's CRI enjoys widespread use, its limitations are well recognized, and the need for a viable alternative is increased by the proliferation of solid-state lighting (SSL), that offers tremendous scope for spectral engineering and optimization.
The DOE continues:
Built on the progress made by many other researchers over the past two decades, and synthesizing many of their concepts, TM-30-15 addresses many of the CRI's limitations, providing more information with greater accuracy. With two main numerical parameters and other visualization tools--such as a color distortion icon—for better understanding the rendition of specific hues, it provides a more complete characterization of color rendition than a fidelity metric alone can. And with a greater number of samples (99) than the CRI, TM-30-15's values are harder to selectively optimize and should provide a better representation of average color rendering.
The DOE says it will host two 90-minute webinars on TM-30-15 next month: one on September 15 that covers the basics, the development process, and the ongoing steps toward widespread adoption; and a follow-up on September 22 that focuses on the math and color science underlying the calculation engine, the derivation of the new set of 99 color evaluation samples, and why the improvements are important. Both webinars start at 1:00 p.m. EDT. To register or for more information, visit the DOE website.
SOURCE: IES; https://www.ies.org/PDF/PositionStatements/PS-8-14.pdf and the DOE
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.