Fig. 4
From: Photographic evidence of luminescence during faulting in granite
CIE xy chromaticity diagram showing sRGB color space and locations of primaries. The open square shown in the center is the D65 white point. The RGB values in this diagram are scaled by luminnance Y so that D65 corresponds to RGB values of 1.0/1.0/1.0. The outer curved boundary is the monochromatic locus, with wavelengths are shown in nanometers and + are plotted at 5 nm interval. Apices of the dashed triangles are R, G and B primaries for sRGB. Two open circles respectively indicate observed sRGB values for two bright spots. Note that these circles are apparently located on the line connecting the D65 white points which has equal RGB values, and R and B primaries, respectively.