Colour

Explanation

A set of colours is formally defined to be harmonious if the colours produce mid grey when they are mixed in equal quantities. We can extend this definition to cover unequal combinations of colours, but in that case it’s more usual to refer to colour balance

The colours in a region are said to be balanced if they produce mid grey when they are mixed in proportion to the area covered by each colour. In other words, colours are balanced if their weighted average is mid grey. The colours in the illustration are balanced in this technical sense.

A colour scheme is described as high key if the weighted average of the colours is a light grey. It is described as low key if the weighted average is a dark grey. It may described as intermediate key or mid key if the weighted average approximates mid grey. It is described as having a colour cast or a colour bias if the weighted average isn’t grey but has a detectable hue.

Observations

• These formal definitions may be applied to the colours in photographs, paintings, colour schemes or any surface.
• This process of averaging the colours is also used for automatic colour correction.
• The advantage of the formal definition is that it can by applied blindly by a computer program, as it is here, to generate formally harmonious combinations. Nobody would suggest that artists and designers should blindly follow these rules.
• Both Itten in the Bauhaus and Munsell in the USA discussed the idea of balancing colours in unequal quantities. (Itten called it the contrast of quantity.) Both these theorists arrived at concepts more or less similar to the one described here. In each case their investigation was limited by the technology available at the time.