Advancing the effective use of light for society and the environment.

Wednesday, October 13, 2004

New Lighting Answers clarifies color and how it is measured
Image: Lighting Answers screen shot

The National Lighting Product Information Program (NLPIP) has released a new publication that looks at color and explains how it can be measured and quantified. Lighting Answers: Light sources and color examines methods to approximate color perceptions in people. Color is not a physical property of objects, but rather a human physiological and psychological response to light. A host of measurements are now available to describe such factors as the color appearance of light sources and objects, the ability of a light source to render colors accurately, and the stability of color properties over a lamp’s lifetime. The human visual system is complex, however, so these measures are only approximations, and their usefulness is limited.

The lighting industry needs to quantify color properties, and in order to provide information useful for specifying electric light sources properly, Lighting Answers: Light Sources and Color describes many of the methods for characterizing the color properties of light sources. It also addresses these methods’ strengths and weaknesses. Part I focuses on the metrics used to describe the appearance of light emitted from a light source, and it describes the human color vision system. Part II focuses on the color appearance of objects when illuminated by a light source. It proposes a “triangulation” method for describing color rendering to help lighting specifiers to select light sources based on their ability to show object colors. This section also discusses the relationship between color rendering and luminous efficacy (lumens per watt). Older light source technologies forced a trade-off between the two, but many products now available provide both good color properties and high efficacy.

For more information, read Lighting Answers: Light sources and color.

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The Lighting Research Center (LRC) is part of Rensselaer Polytechnic Institute and is the leading university-based research center devoted to lighting. Founded in 1988, the Lighting Research Center has built an international reputation as a trusted and reliable source for objective information about lighting technologies, applications, and products. Its mission is to advance the effective use of light and create a positive legacy of change for society and the environment.



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