In the CIELAB colour space, each perceptible colour is defined in a three-dimensional coordinate system. For the measurement, both the illumination (light type and angle) and the measurement geometry are decisive. With the 45°/0° geometry, a circular directional illumination at a 45° angle and a view perpendicular to the same plane (0°) is realised. This takes the influence of the surface structure into account. In the case of the d/8° geometry, the surface is measured at an 8° angle to the vertical under diffuse illumination. By standard, samples are illuminated with D65 daylight beneath 10° normal observers.