What is the ideal use of color rendering index (CRI)?

The ideal use of color rendering index (CRI) is to indicate how colors appear under a light source. CRI is a measure of a light source's ability to accurately reproduce the colors of various objects in comparison to a natural light source. A higher CRI value (closer to 100) means that the light renders colors more naturally and vividly, which is particularly important in settings such as art studios, retail environments, and interior design, where accurate color perception is critical.

The other options relate to different aspects of lighting. For instance, the lifespan of a bulb pertains to its durability and longevity but does not involve color rendering. Energy savings are assessed by comparing the efficiency of light fixtures, usually measured in lumens per watt, rather than by color rendering capabilities. Lastly, brightness levels, typically measured in lumens, indicate the intensity of light emitted, which is separate from how that light interacts with colors. Thus, the focus of CRI is specifically on the accuracy of color representation under a given light source.