The hue is determined by the wave length of a colour, which makes it possible to distinguish between different colours.

A colour is generally characterized by the hue, but also by its lightness and saturation.

The wave length of visible light spans from approx. 400 - 700 nm. The following colours are perceived at the respective wave lenghts:

 

Hues
<strong>The spectrum colours</strong>
<strong>Hue</strong> <strong>Wave length</strong>
Purple 400-420 nm
Blue 420-490 nm
Green 490-575 nm
Yellow 575-585 nm
Orange 585-650 nm
Red 650-750 nm