Color rendering and color appearance are the most crucial aspects of lighting quality for LED luminaires. Below is more information about each of them.
This is communicated by use of correlated color temperature commonly shortened as CCT on the Kelvin scale. For the interior lighting applications, the warm white should range 2700 to 3000 kelvins and in some cases the neutral white is about 3500 to 4000 kelvins. The cool white LEDs have high CCT and thus tend to give higher efficacy at a lower cost. It is bluish in color. However, expectations of the user may not be met. Of late the number of the high efficacy LED luminaires has been increasing and thus they are available in both neutral white and warm white colors. Two light sources having identical CCTs may render the object colors differently due to differences in spectra. CCT provides a good indication of whether the light source will appear yellowish or bluish. Duv is an additional metric which can assist in identifying sources with pinkish or greenish hues.
It is also referred to as color rendering index or CRI. It is used to measure the ability of light source to render colors compared to other incandescent reference sources. The manufacturers of the LEDs claim a CRO of 75 of higher for the phosphor converted and warm white devices in the LED industrial lighting market. Generally, a minimum CRI of 75 is needed for interior lighting.
CRI of 85 or higher shows excellent color rendering. CRI has been found not to be accurate for the RGB (red, green and blue) LED system due to the poor prediction of appearance quality of the saturated color objects. This may as well fail to correspond well to the human perception of color quality. Both CCT and CRI can only get you in the ballpark for matching and selecting lamp colors. There are several color rendering metrics which have been proposed over the last few years. For now, the color rendering of the LED luminaires are being evaluated for more information.