Color rendering is the effect of a light source on the color appearance of objects as compared to the appearance of the same objects under a reference light source. Light sources are rated using the Color Rendering Index (CRI).
The CRI can range from 0 to 100, with 0 being the worst quality light and 100 being the best quality light. Reference light sources have a CRI of 100. Color rendering is very important when objects under a light source need to match their actual color as closely as possible. Some uses for light sources with high CRIs include areas with security cameras, areas where photographs are taken, and clothing stores.
Choosing the right light source when considering CRI is a tough task. Low CRI light sources are cheap to operate, but give off low quality light. Light sources with high CRIs have higher quality light, but are more expensive to purchase and operate. It is important to look at the effect color rendering will have on a space as well as the cost of light sources when choosing the type of light for use.
Daylight is considered a perfect light source because it emits light throughout the entire color spectrum. However, no light source is perfect because none are able to emit equal amounts of each color throughout the spectrum. Therefore, daylight, with a CRI of 100, is the best source.
As seen in the table, incandescent (and halogen) sources are the best choices when it comes to color rendering. Changing the coating within a bulb can also help increase a source’s CRI, as seen with mercury and fluorescent sources.
Color rendering is very important when working with a space that may require colors to appear as true as possible. Light sources with high CRIs may cost more, but give off higher quality light. Low CRI light sources may be more cost effective, but may change the color of objects within a space. It is important to look at cost, as well as color rendering and light quality, when choosing light sources for any project.
TES Engineering’s designers can provide additional guidance regarding the Color Rendering Index and can help you choose the correct lighting products for your space.