TM-30-15 – COLOR RENDERING INDEX (abbreviation: Rf , Rg)
TM-30-15 is a new IES standard for evaluating the color rendering of light sources and uses 99 reference colors distributed over the entire color space. As a result, it makes use of significantly more colors and hues for the calculation of fidelity index Rf, which describes the same relationship as color rendering index Ra. Gamut index Rg provides information concerning color saturation and color shift, and is similar to gamut area index GAI used previously for the examination of color rendering. Detailed information concerning the evaluation of color rendering can be found in the following graphics which are included in the meter.
Re is the arithmetic mean value of color deviation demonstrated by test colors 1 through 14 in accordance with DIN 6169, and test color 15 (Asia skin color). As a supplement to color rendering index Ra, this value also takes the saturated colors, leaf green and skin tones into account.
GAI is a measure of the vividness of color representation and is used primarily for the evaluation of exhibition and museum lighting. It’s an indicator of how well the octahedral surface in the color space defined by the eight Ra test colors is covered by the light source. In combination with Ra, the following statements can be made regarding color rendering.
test
LOW GAI
HIGH GAI
low Ra
incorrect and pale colors
incorrect and intensive colors
high Ra
correct but pale colors
lifelike color representation
Ee is the unweighted irradiance within a range of 380 to 780 nm.
LER is the quotient of illuminance Ev / irradiance Ee. It’s an indicator of how much of the generated radiation of a light source is perceived as light by the human eye.
