The NCS palette (Natural Color System) derives from a perceptual chromatic system, modeled as a biconic three-dimensional space. It has been created by the Scandinavian Colour Institute of Stockholm.
It is based on the human eye colour vision system, which is sensitive to the opposition among the six fundamental complementary colours: white, black, yellow, red, blue, and green.

Colours are defined by three values, which specify the quantity of blackness, the chromaticity and a percentage value between two fundamental colours green, blue, red, and yellow. For instance, the colour “Brilliant red” is identified by the code S 1085-Y80R, where 1085 stands for a 10% blackness and a 85% saturation, and Y80R means a colour between yellow (Y) and red (R), with a quantity of red of 80%.

The difference between the two systems is that the first catalogues a narrow and arbitrary set of about 2000 well-defined and standard hues. On the other hand, the second provides a code that univocally defines all of the 10 million colours that the human eye can distinguish.

Moreover, being a system based on opponent colours, it helps finding matching colours by similarity or contrast. However, the RAL palette is still the most used in industrial paints and colours.