TM-30-18 defines 99 color evaluation samples

The fidelity index R_f is the average and calculated by determining the arithmetic mean of color difference ∆E. TM-30-18 defines 99 color evaluation samples and each sample has different spectral reflectance to the reference illuminant, thus we will get 99 different color fidelity values R_f,CESi, while individual R_f,CESi values may be imperfect at predicting the fidelity of similar color, due to metamerism, but it is still helpful to identify light sources with greater disparity in rendition of similar-colored objects when considered collectively.

CES 15 and CES 18 color rendering index

For specific attention, the CES 15 and CES 18 may be most concerned since they represent human skin tones. Comparing to R_i of Color Rendering Index, the R_{f, CESi}  of TM-30-18 is more comprehensive to evaluate much more colors.

• Local chroma shift (R_{cs, hj})

  Represent a relative average chroma shift as percentage, negative value indicates a decrease in chroma, and positive value indicates an increase in chroma, j = 1 ~ 16.
  

• Local hue shift (R_{hs, hj})

  Represent the hue shift within a hue-angle bin, negative value indicates a clockwise shift, and positive value indicates a counterclockwise shift, j = 1 ~ 16.
  

• Local color fidelity (R_{f, hj})

  Same calculation procedure as Rf and range as 0 – 100. Rf, hj is analogous to the special color rendering indices of the CIE Test Color Method, j = 1 ~ 16.
  

Introduce CRI

Gamut index (R_g)

In addition to an improved color fidelity metric, the TM-30-18 method introduces an additional dimension to color quality through the gamut index (R_g). The R_g gamut index provides information about the relative range of colors that can be produced (via reflection) by a white light source. A score close to 100 indicates that, on average, the light source reproduces colors with similar levels of saturation as an incandescent bulb (2700K) or daylight (5600K/6500K). For LEDs of decent color quality, R_g can typically range between 80 and 120, with higher scores representing higher overall levels of saturation.