Figure 2:

CIE 1931 XYZ color space. (a) Schematic diagram of the color perception process, where the object (Bing Dwen Dwen) reflects, transmits, or absorbs certain amount of the incident EM waves through various physical and chemical processes. The subsequently reflected (transmitted) light is received by the photoreceptors on human retina, generating signals to the visual cortex for the final color perception. (b) Color matching functions $\overline{x}(\lambda )$ , $\overline{y}\left(\lambda \right)$ and $\overline{z}(\lambda )$ . (c) The CIE 1931 XYZ chromaticity diagram and five popular color gamut standards. (d) Reflection spectra with different central wavelengths (upper panel) and the corresponding coordinates in the CIE XYZ color space (lower panel) to illustrate the hue property of a color. (e) Reflection spectra with different bandwidths (upper panel) and the corresponding coordinates in the CIE XYZ color space (lower panel) to illustrate the saturation property of a color. (f) Reflection spectra with different peak intensities (upper panel) and the corresponding coordinates in the CIE XYZ color space (lower panel) to illustrate the brightness property of a color.