OUGD401 - Colour Theory - Lecture

There is no way to be sure that an apple is red, this is because of the relationship that we perceive colour. Spectral colour is a colour that is evoked by a single wavelength of light within a visible spectrum. In order to perceive colour, light needs to be present. What happens when we see a blue sky, it is a reflection of short white light wave lengths. The diagram below shows the spectrum of white light in relation to their wave length. Because the blue wave lengths are so light, the sunlight bounces off and reflects off them.

Our eyes can interpret red, green and blue however, when our green and blue cones are simultaneously stimulated, we can perceive other colours. Additive colour light is referred to as RGB whereas subtractive colour CMY. When we deal with RGB we are dealing with screens, when we deal with CMY we are working with printing.

Chromatic value = Hue + tone + saturation

Rods convey shades of black white and grey

Cones allow the brain to perceive colour

The first thing we recognise when perceiving colour is rods acknowledging tone. We can then see the contrast of hue which is determined by the distance between colours on the colour wheel which in turn creates contrast. The third element which makes up the chromatic value of a colour is saturation.

The contrast of temperature is assigned to the idea that a colour can be perceived as temperature.