Relationship between chromaticity and color
Having completed the discussion of chromaticity allows us to revisit the question: What is color? One could certainly define a color by its location in the chromaticity diagram (i. e. by its chromaticity). However, the CIE (1986) adopted a more general definition of the term “color” that goes beyond the location in the chromaticity diagram. The CIE’s broader definition of color includes chromaticity as well as brightness. That is, we can keep the chromaticity of a light source the same but change its luminous intensity (brightness); this, according to the CIE definition, changes the color of the source. If, on the other hand, we restrict our considerations to a single brightness level, the terms “chromaticity” and “color” can be used synonymously.
The location of a chromaticity point can be expressed by the dominant wavelength and saturation (or, alternatively, by hue and saturation). Thus, the CIE definition of the color of light is given by the dominant wavelength, saturation, and brightness. The color of an object is given by the dominant wavelength, saturation, and lightness.