A theory of unique hues and colour categories in the human colour vision

A novel approach to assessing colour appearance is described. It is based on a new technique—partial hue-matching—which allows for measuring colour in terms of component hues objectively, without resorting to verbal definitions. The new method is believed to have a potential to be as exact as colorimetric techniques. In contrast to classical colour matching, which implies visual equivalence of lights, partial hue-matching is based on judgements of whether two lights that are different in colour have some hue in common. The major difference between classical colour matching and partial hue-matching is that the latter is intransitive, whereas the former is generally believed to be transitive (though see Logvinenko, Symposium on 75 years of the CIE Standard Colorimetric Observer, Vienna, Austria, 2006). Formally, partial hue-matching can be described as a reflexive and symmetric binary relation (i.e., tolerance). The theoretical framework of tolerance spaces is used for developing a theory of partial hue-matching.