Lecture 10: Colour Theory 1

Systematic Colour (Part 1) - An Introduction to Colour Theory 
colour is infinite. There are infinite gradient, tones, shades. 

physical -> physiological -> psychological

physiological = human interpretation of colour

physical aspects of colour = optics, refraction etc

spectral colour is a colour that is evoked by a single wavelength of light within a visible spectrum. A single wavelength, or narrow band of wavelengths generates monochromatic light. Every wavelength of light is perceived as a spectral colour in a continuous spectrum. The colours of similar or sufficiently close wavelengths are often indistinguishable by the human eye. 

wavelengths of colour

All colours have different wavelengths and light is made up of all of the different colours we can see vibrating at different wavelengths.

Our perception of any colour is based on the eye receiving light that has been reflected fro a surface or an object. 

The eye contains two kinds of receptors:

Rods convey shades of black, white and grey. Cones all the brain to perceive colour.

Types fo cones:

1. sensitive to the red-orange light

2. sensitive to green light

3. sensitive to blue-violet light

When a single cone is stimulated, the brain perceives the corresponding colour. But two cones can be stimulated so combinations of colours can be perceived e.g. the stimulations of red-orange and green cones show us yellow.

Figure 1

Figure 1 shows the colour spectrum through the eyes of different conditions and how it can be so different.

Josef Albers (1888-1976)

Johannes Itten (1888-1967)

Colour - Pigment - Media

Johannes Itten colour wheel

There are thought to be primary, secondary, tertiary colours in the colour wheel that when mixed can make endless combinations.  

Primary + primary = secondary

primary + secondary = tertiary

When you mix opposite colours, the wavelengths are cancelled out and a brown/grey colour is always created. (neutral tertiary)

Spectral colour

The eye cannot differentiate between spectral yellow, and some combination of red and green. The same effect accounts for our perception of cyan, magenta, and the other in-between spectral colours. 

Colour mode

Red, green and blue = relates to light

RGB - anything screen based

CMYK - anything printed

Chromatic values - hue, tone and saturation 

Hue - initial response to a colour e.g a range of colours that sit within the violet/green/blue spectrum

Luminance - how bright tit is, how much light it reflects, how vivid the colour is

Tint - adding more or less white to a colour which also affects its luminance

Saturation - the amount of a colour we can see and how pure it is