"The Apparent Physicality of Colour", CSA national conference "Colour Matrix", Oct 31 - Nov 2, 2025

This is a recording of my presentation given at Colour Matrix Sydney 2025 a couple of weeks ago. An illustrated pdf of the complete text of the presentation is available at https://www.academia.edu/145038315/Th... Abstract: In science, colours such as red, green and white are regarded, not as physical properties as such, but as perceptions of physical properties created by our visual system. Yet colours certainly seem to us to be physically located outside us in objects and in light. In this presentation I examine this perceived physicality of colour and how it is considered to arise. In layered models of colour perception, colours perceived as belonging to objects arise as unconscious estimates of the overall spectral reflectance of objects, estimates that in daylight are consistent enough to lead us to think of these colours as seemingly inherent properties of objects. Layered models of colour perception contrast with what I refer to as the “colour-photo” or “one-layer” model that proceeds from the usually unstated and seemingly commonsense premise that we perceive only a single colour at each point in the visual field, as in a colour photograph. This model, which I've noticed among many colour educators, has led some to conclude that we only think we perceive objects as having a constant object colour, and others to talk of the constant object colour, since it’s apparently not a perception, as a property actually inherent in the object. But this is to overlook the fact that we experience object colours and illumination as paired, superimposed perceptions whenever we visually perceive objects. In painting, the apparent physicality of colour understandably leads us to assume that the colours of our paints reside in our paints, and so, that when we mix our paints, we are mixing their colours. This assumption leads to confusion in student painters when paint mixtures don’t do what they should “in theory” – the theory being that we are “mixing colours”. Further, I argue that the characteristic tenet of traditional colour theory, that the "primary" colours red, yellow and blue cannot be “created” by “mixing” other colours, arises from the assumption that the red, yellow and blue unique hues that we perceive in our paints actually reside and mix in those paints. This assumption leads to explanations of paint mixing that are flexible enough to appear to explain any mixture without disturbing the "primary" status of red, yellow and blue.