Figure 1: Semantic contours for chromaticity differences from the chromaticity center in the CIE x,y chromaticity diagram for a warm white chromaticity center, the Planckian radiator at 2500 K; x=0.4770; y=0.4137 (light green dot). Going off the center in any direction, contours indicate “good-very good” (green contour), “good” (yellow contour), “moderate-good” (orange contour), “low” (red contour) and “bad” (lilac contour) perceived color agreement with the center. Contours of constant chromaticity differences (Δu’v’=0.001 - Δu’v’=0.007 i.e. approximations of MacAdam ellipses) measured from the chromaticity center are also shown