Michael Newall: "Impossible Colours"

Michael Newall, Adelaide University, presents themes from his book Impossible Colours

Abstract
"Impossible" colours are those that combine opponent hues in ways prohibited by opponent processing theory: i.e., reddish greens and yellowish blues. Most colour science and philosophy holds that impossible colours can never be experienced, although there are indications this is changing. This presentation starts by showing some purported examples of impossible colours drawn from scientific literature and other sources. It gives a sketch of mechanisms used to describe how subjects can see these colours and outlines the general shape of a model of perceptual processing that could accommodate impossible colours. Finally, it indicates a consequence for philosophy – that objectivism about colour is difficult to maintain if impossible colours can be experienced.