Colour is the visual perceptual property in humans to the categories called red, green, blue and others. Colour derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. These physical or physiological quantifications of colour, however, do not fully explain the psychophysical perception of colour appearance.
Dimensions of Colour
There are three dimensions to colour-hue, value and intensity. This makes a colour multidimensional-any colour appearance can be described in terms of these three dimensions.
Hue
Hue refers to the names of the colours. It is the contrast between redness, blueness and greenness. We most typically think of hues as coming from white light divided into the visible spectrum-red, orange, yellow, green, blue and violet or as a “circle of hues” or “colour wheel”.
Value
Value refers to the lightness or darkness of a colour. It is often related to a greyscale where white is the lightest value followed by a series of greys to black, the darkest value. The hues are located somewhere in between the extremes of white and black in value. A colour value scale is a hue mixed with white to form tints and with black to form shades of that hue. Red plus white make pink. Pink is a tint or light value of the hue red. Red plus black makes brown. Brown is a shade or dark value of the hue red.
Intensity/Chroma
Intensity refers to the purity or impurity of a hue. The more pure hue a given colour contains, the more intense it is. Opposing terms used to describe this contrast are intense vs. grey, saturated vs. desaturated or bright vs. dull. When the colour is too bright and its intensity needs to be reduced, we will often say,” Gray that colour.” The most typical ways to grey colour are to add grey (black and white) or by adding some of the complementary colour.
Warm and Cool Colours
Warm colours are vivid in nature. They are bold and energetic. Warm colours are those that tend to advance in space; therefore, caution needs to be taken so you do not overwhelm your content with eye-catching hues.
Cool colours are soothing in nature. They give an impression of calm and rarely overpower the main content or message of a design. Cool colours tend to recede; therefore, if some element of your design needs to be in the background, give it cool tones.
Advancing and Receding Colour
Warm hues seem to advance and cool ones to recede. A cool light colour on the wall thus helps to make a small room look larger.
Tints and Shades
In colour theory, a tint is the mixture of a colour with white, which increases lightness, and a shade is the mixture of a colour with black, which reduces lightness. Mixing a colour with any neutral colour, including black and white, reduce the chroma, or colourfulness, while the hue remains unchanged.
Colour Systems
1. Prang system
It is based on Brewster-Newton theory. It deals with primary, secondary, and tertiary colours. There are 12 basic hues in the prang colour system, namely: three primaries, three secondary and six intermediates.
Colour Classification
Primary colours – the root of all colours.
Yellow
Blue
Red
Secondary colours – produced by the mixture of any two primary colours.
green (yellow and blue)
orange (yellow and red)
violet (red and blue)
Intermediate colours- produced by the mixture of a neighbouring secondary colour in the colour chart.
yellow-green
yellow-orange
red-orange
Red-violet
Blue-violet
Blue-green
Tertiary colours – produced by the mixture of two secondary colours.
russet or reddish brown (violet and green)
olive or brownish yellow (orange and green)
slate or bluish grey (violet and orange)
Quaternary colours – produced by the mixture of two tertiary colours.
buff (russet and olive)
sage (olive and slate)
plum (slate and russet)
2. Munsell system
Disregards primary and secondary colours. According to Munsell, it gives an excess of orange and yellow in the chart. The system establishes five principal hues: red, yellow, green, blue, and purple. The five intermediate hues are yellow-red, green-yellow, blue-green, blue-purple, and red-purple.