What does chromaticity encompass?

Chromaticity specifically refers to the quality of a color that includes two key aspects: hue and saturation, while deliberately excluding brightness. Hue is the attribute of color that allows us to classify it as red, blue, green, etc., and saturation describes the intensity or purity of that color. In the study of color theory, understanding chromaticity is crucial for tasks such as color matching, color mixing, and visual representation in design work, where brightness is not considered part of the chromaticity but rather a separate characteristic of color perception.

The other options provide definitions that either conflate brightness with chromaticity or focus on aspects that do not pertain to the essence of chromaticity itself. For example, options mentioning brightness or lightness speak to separate dimensions of color, while others might imply misinformation about how colors are qualitatively assessed in terms of chromaticity.