The IES TM-30 method evaluates a source against a reference using 99 color samples drawn from real objects. Rf, the fidelity index from 0 to 100, is the counterpart of CRI Ra; Rg, the gamut index, shows whether colors look more saturated (above 100) or duller (below). The color vector graphic and hue-bin values show which hues shift, such as reds losing chroma, letting designers ask for specific looks.
TM-30 shows Rf 88 and Rg 104 with the reds pushed a little more saturated, which is what the retailer wants on the clothing racks.
Also heard as
- IES TM-30
Do not mix it up with
- CRI: CRI uses eight pastel samples and one fidelity number; TM-30 uses 99 samples and adds saturation and hue detail.
Related terms
CRI
Color Rendering Index: a score up to 100 for how true surface colors look under a source compared with a reference light.
R9
The color rendering score for a strong saturated red sample, not included in the general CRI average.
SPD
Spectral Power Distribution: a graph of how much power a light source emits at each wavelength.
Metamerism
The effect where two colors match under one light source but not under another, because their spectra differ.