DIN System
(Beuth - Vertriels G. m. b .H Berlin, Germany).

This is the official German standard colour system developed by M. Richter & Associates (1953, 55, 61). The colour is described in its three dimensions by the terms hue (DIN - Farbton), saturation (DIN - Sättigung) and relative lightness (DIN - Dunkelstufe). The DIN - Farbton have the same dominant wavelength or complementary wavelength with CIE standard source C. The hue circuit is divided into 24 perceptually equal steps of DIN - Farbton. In the 1931 CIE chromaticity diagram loci of constant chroma (DIN - Sättigung) are ovals around the chromaticity point of source C. These loci are the same for all values of lightness (DIN - Dunkelstufe). The DIN - Dunkelstufe is obtained as the logarithmic function of ' relative lightness' h = Y/Yo Where Y is luminous reflectance of sample, Yo is the luminous reflectance of the optimal colours having the same chromaticity as the sample. Constant Dunkelstufe means constant relative lightness h, but usually not constant lightness in the sense of perceived lightness.

The function itself is defined as:

The introduction of relative lightness rather than lightness itself is said to give the DIN - hue a psychologically balanced appearance. Thus the locii of constant DIN Sättigung do not approach closely the corresponding locii of constant Munsell chroma (Relationship Kundt & Wyszecki 1955).

Other colour order systems, such as the German Ostwald and the Swedish Heselgrem, are not often used outside their pwn countries, except a version of the Ostwald called the 'Color Harmony Manual' used by designers in the USA.