Abstract
Colour has been central to the philosophy of perception, and has been invoked to support the mutually opposing views of subjectivism and realism. Here I demonstrate that by understanding color as an appearance, we can articulate a sensible middle ground: although colour is constructed by the brain, it corresponds to a real property of objects. I will argue here that (1) color is a perceptual quality, a reading of the outside world, taken under biological and environmental constraints, and a meaningful property in the perceiver's internal world (2) the core property of colour constancy makes sense only if colour is subjective and (3) measuring colour constancy illustrates both the need for and the difficulty of subjective descriptions of appearance in vision science. For example, colour names give parsimonious descriptions of subjective appearance, and the technique of colour naming under changing illumination provides a reliable method for measuring colour constancy which is both objective and subjective at the same time. In measurements of simultaneous chromatic contrast, responses of "more red" or "more green" are also appearance descriptors which can be quantified. Achromatic adjustment methods ("adjust the patch until it appears white") also map a physical stimulus to the subjective experience of neutrality. I will compare the results of such techniques with our recent measurements of colour constancy using techniques that do not rely on appearance descriptors, in particular, the measurement of discrimination thresholds for global illumination change in real scenes.
Meeting abstract presented at VSS 2013