The function of colour – an introduc tion to colour theory and a definition of terms Axel Buether
Colour is both a phenomenon and a medium of visual perception and communication. Colour illuminates and light colours As a phenomenon [1], colour shapes how people experience the environment visually, while as a medium, it conveys meaning, emotional moods and functional information. As luminous colour it appears atmospheric and diffuse to the viewer, while as non-luminous colour, shape and form materialise from it. The antithesis of coloured light is darkness, which shows its influence on the aesthetics and function of the phenomenal world in the spatial play of shadows. The complex sensations of colour result from the interaction of light with the entire organism. Colour and light form two sides of the same phenomenon, since colour illuminates and light colours. Colours shape the appearance of the natural environment, which varies in terms of climate and topography. They make it possible for diverse forms of life to orient themselves and to communicate in ways specific to their species. Colour creates identity. These biological functions do not only shape the natural environment – they also determine the aesthetics of the cultural space that illustrates the forms of visual communication between people. Colour’s potential for expression and communication evolves with the cultural development of individuals and societies. It finds expression in all manifestations of life, in words, pictures, objects, spaces and performances. Colour is the most important design tool for configuring the environment aesthetically, as the abstract lineal structures of the planning phase take on a physical form in the atmospheric and material manifestations of built space. The entire material culture is designed according to the biological
principles of visual perception. People must be able to identify the purpose of an artefact by looking at it in order to orient themselves, use it or protect themselves against it. Orientation is an essential function of colour, since the spatial resolution of all material structures increases exponentially with every nuance of brightness and perceptible hue. This principle can be seen in the pixel composition of a digital image. Whole image planes disappear or appear, shift, or form new relationships when colour and brightness are manipulated. The separation of the colour spectrum into chromatic and achromatic colours derives from the mode of operation of the visual system, which processes the colourfulness and brightness of luminous and non-luminous colours separately. By practising colour perception, the achromatic components of a hue can be identified and assigned to a grey tone in the scale between black and white. Similarly, values can be assigned to the chromatic components of pure colours or colour mixtures whose classification reflects the processing of visual signals in the brain, as explained elsewhere (see p. 12ff.). Pure black, white and grey hues only occur rarely in nature, since organic and inorganic materials always include coloured particles as a result of their development process. The aesthetics of achromatic colours are based on the abstraction processes of artistic cultural techniques in which information is generated by lines and gradual nuances between light and dark. Black ink and white paper now dominate not only text and image production, but also the appearance of the entire cultural space via the industrial dyeing of raw materials. The most frequently
used pure achromatic pigments are crystalline titanium white and printer’s carbon black. The latter is reduced as a by-product of combustion processes to almost pure carbon. These two bio logically insignificant achromatic colours account for about two-thirds of worldwide pigment production [2]. The effects of this on the appearance of the Earth can now be observed from space. The fundamental difference between natural and cultural space can therefore be recognised as regards both form and colour. The reduction of the spectrum to achromatic colours means that the perception of the environment shifts. Some levels of information, such as light and shadow, become more prominent, while others disappear completely. The non-use of chromatic colours increases the per ception of the contours and volume of buildings and objects in proportion to the decrease in the importance of the surface. The emphasis on the outlines puts lengths, widths, depths, proportions and additions at the forefront of perception. Information on the time of day, mood, atmosphere, materiality and tactility becomes less important as a result of the chromatic colour abstraction process and recedes into the background. Colour, which thereby loses its meaning is used merely as a filler for linear structures, easily becoming decoration. The amount of colourfulness shifts the focus of the object and spatial perception. Colour should therefore always be used purposively in architecture and design. Too many colours (or more precisely, too much colour-coded information) can be just as disorientating as too few colours. Colour design is visual communication. In nature, colour is a result of evolution: as a result, all the 7