Color rendering capacity

Color rendering capacity is a measure of how well colors are represented under artificial light. It is one of several measures of color rendering index, indicating the extent to which a wide range of colors may be distinguished under a given light source.

Technical definition
Associated with each type of spectral power distribution, one and only one color solid can be constructed in a uniform color space. It has been proved that this color solid comprises all the object colors producible under illumination of that spectral power distribution with one unit luminous flux, and the volume of the color solid determines the upper limit for the number of the object colors producible under the given spectral power distribution with one unit luminous flux. This volume of the color solid associated with the spectral power distribution is called the color rendering capacity. It may be expressed as a proportion of the volume of the color solid associated with the equal energy spectrum, and is output in this form from computer software known as “CRC99”.

Sample values
The color rendering capacity is 0.35 for high-pressure sodium lamps, 0.97 for “Deluxe” fluorescent lamps, and 1.00 for equal energy spectrum respectively. These results conform with everyday experience: high pressure sodium lamps are rarely used in stores for commodity lighting, as the commodities would appear in monotonous yellow shades while the same commodities under deluxe fluorescent, at the same light level, display a much wider variety of colors. The color solid and the color rendering capacity calculated for the spectrum of the Deluxe fluorescent lamp F7 is shown on the picture.

Source From Wikipedia