Approaches to color rendering measurement

Abstract

Color rendering refers to a light source's ability to make the colors of illuminated objects appear natural or accurate. The color rendering index (CRI) is currently the only internationally-standardized way to assess a light source's color rendering abilities. The CRI has shortcomings in application, however, and its problems are pronounced when applied to newer lighting technologies, such as light-emitting diodes (LEDs). Since the introduction of the CRI to the present day, alternative methods have been proposed and studied. Some methods are based on the shape of the spectral output of the source, considering broadband sources to have better color rendering than sources with spectral peaks or valleys. Several proposals share the basic method of CRI, with modifications to improve performance. Still other ideas are based on measures of the gamut area of rendered object colors. The International Commission on Illumination (CIE) is in the process of developing and recommending a new metric of color rendition.

Keywords:

• color rendering
• colorimetry
• light sources
• light-emitting diodes