Classification systems cover the many different ways of classifying colours by bringing its parameters together in one figure so that it is easy to specify a particular colour by, for example, its:
(1) HUE, or colour of the rainbow or spectrum, Red, Yellow, Green, Blue, Purple & intermediates,
(2) LIGHTNESS or DARKNESS (called Tone by painters or Luminance by scientists), and (3) COLOUR FULLNESS (called Intensity or Strength by artists and Saturation by dyers and scientists).

This covers compartments of knowledge known as metrology and taxonomy that permeate all the other sections, and will be cross-referenced to most other subjects.

The First 3D Figures for the Specification of Colours
In order that the three main parameters of colour, Hue, Tone and Intensity can be connected together rationally in one figure, this has to be a three-dimensional figure or COLOUR SOLID.

The ancient Greeks saw two classes of colour which they did not connect together, namely the rainbow colours (such as Red , Yellow, Green, Blue and Violet) and the earth colours (such as the Red and Yellow Ochres, Carbon Black and Lime White). See Democritus, Aristotle and the Roman Pliny.

It was not until the 18th century that the German mathematician, Tobias MAYER (1728-62), devised a colour pyramid to contain the parameters of colour. This consisted of a pyramid of equal-sized triangles stacked in graded mixtures from Black to White through the colours. Improvements were made to this in 1772 by having three primaries in a triangle with Black at the centre, stacking smaller and smaller tirangles whiter and whiter with pure White at the apex. The creator of this first practical colour solid was the Swiss theorist, Johann Heinrich LAMBERT (1728-77). See Colour Solids.

Attempting to measure colour by visual judgement alone is hampered by the fact that visual responses are often highly individual. Even when defective colour vision and differing conditions of illumination do not present a problem, the language and terminology used to communicate colour appearances is commonly imprecise or unreliable.

It may be additionally unfortunate that specialists seeking different forms of colour identification have tended to accumulate their own colour terminology. The scientist may describe colours with one set of names and numerical notations, while the artist may employ others. Geologists, horticulturists, philatelists, and manufacturers or paints, dyes, printing inks, plastics and cosmetics have each adopted their own colour terms, with the outcome that different terms may identify the same colour, or the same term may be used to identify colours which differ in appearance.

Hence, the need to establish precision in the matching of colours has led to numerous systems of colour measurement and notation. An early practical attempt, the Natural System of Colours, was made prior to 1766 by the English entomologist Moses Harris. Another system, A Nomenclature of Colours, was first published by the American ornithologist Robert Ridgway in 1886, followed by Albert Munsell¹s A Color Notation in 1905, Wilhelm Ostwald¹s Die Farbenfibel in 1916, and Maerz and Pauls¹ Dictionary of Color in 1930.

References
George A. Agoston (1980), Color Theory and Its Application in Art and Design. New York.
G.J. Chamberlin & D.G. Chamberlin (1980), Colour: Its Measurement, Computation and Application. London.
Andreas Kornerup & J.H. Wanscher (1961), Taschenlexikon der Farben. English edition by D. Pavey: Methuen Handbook of Colour. London.
Rolf G. Kuehni (1983), Color: Essence and Logic. New York.
David L. MacAdam (1981), Color Measurement: Theme and Variations. New York.
HALBERTSMA, K.T.A. (1949) A History of theTheory of Colour. Amsterdam
LAMBERT, J.H. (1772) Farbenpyramid. Germany