A colour system (or colour model) is an abstract mathematical method for determining and specifying colours and their relationship to each other.
It is sometimes referred to as colour space, although the latter is the concrete application of a colour model to a colour-producing method (printer, monitor, etc.).
Well-known colour systems are:
- RGB (additive colour mixing with red, green and blue)
- CMYK (subtractive colour mixing with cyan, magenta, yellow and black)
- Lab/CIELab (brightness, red-green axis and blue-yellow axis)
- HSL and HSB/HSV (Hue, Saturation, Lightness and Hue, Saturation, Brightness/Value)