8. Colour

8 - 02 Colour Quantification Systems:
Several artists and theorists have explored the potential of colours and studied colours, to the extent that they could compile their research into comprehensive colour theories. There are many colour theories that a visual artist can use, among which the more popular and widely accepted ones are those devised by Munsell, Ostwald, Chevreul, Rood and Prang.

a. Prang System - This is the system taught in most schools, and often a student does not even know about any other system, unless he chooses to study art or design, or related professions. It is popular because of its simplicity, and its failings can be easily overlooked for school-level art education.

The Prang system has three primary colours: red, yellow and blue. These colours are basic; no other colours can be combined to make them. Primary colours are mixed together to form secondary colours - like orange, green and violet can be mixed together to form intermediate colours - red-orange, blue-violet, yellow-green, blue-green, red-violet and yellow-orange. The primary colours, in a highly saturated form, mixed in combination with black and white will produce an incredible number of different colours, considered as the tertiary colours. However, though these three colours produce all other hues, the hues tend to be weaker, greyer or muddier. For this reason and because the Prang system has never been systematized, the Munsell system finds more acceptance.

b. Munsell System - This system is composed of five principal hues: red, yellow, green, blue and purple. Their interactions form the next level of colours - yellow-red, green-yellow, blue-green, purple-blue and red-purple. In this system, the three colours are quantified so that each specific hue can be correctly identified.

The value of a colour is identified on a scale of 0/ (absolute black) to 10/ (absolute white) with nine visually equal steps between. The symbol 5/ is used to indicate middle grey and all chromatic colours appear halfway in value between absolute black and absolute white. The chroma numeral indicates the degree of departure of a specific hue from a neutral grey of the same value. These numerals range from /0 (neutral grey) to /10, /12, /14, or further, depending on the saturation of the colour.

The complete Munsell notation for a chromatic colour is written as HV/C. A red commonly called vermilion would thus be written 5R5/14. The notation for an achromatic colour is written as 5R/14. The notation for an achromatic colour is written as NV/; a middle grey would be N5/. However, light yellowish grey would need a more precise classification, N8/(Y, 0.2). It is essential in industry that a colour system be used in order to ensure an accurate colour representation from design to manufacture.

c. Ostwald System - This colour theory has four fundamental colours: yellow, red, blue and sea green. These are mixed to create orange, purple, turquoise and leaf green colours. The colour chart is arranged according to the principle that any two colours mixed in equal parts will generate the colour located exactly between them. A hue number is given for each principle colour step, 1 through 24. Ostwald also quantified value in terms of the percentage of black and white contained in the colour. Any colour, with the exception of fully saturated colour, could be described as consisting of a pure hue, white, and black. In practice, most colours do contain a portion of achromatic colour in addition to the pure, fully saturated hue.

The essence of the Ostwald system is to be able to create colour harmony by arriving at colours that have the system hue, black, and white content.

d. Four-colour process - The final major theory is a variation of the Prang colourant system and is mentioned here only because of its importance to future graphic designers and photographers. The four-colour process is actually composed of three primary colours: cyan, magenta, and yellow. The secondary colours are made as follows: magenta plus cyan produces blue; cyan plus yellow produces green; yellow plus magenta produces red. If you mix cyan, magenta, and yellow, you produce black, which is the fourth colour used in the four-colour printing process.