Color model
The Swedish Natural Color System (NCS), widely used in Europe, takes a similar approach to the Ostwald bi-cone. Because it attempts to fit color into a familiar shape based on "phenomenological" instead of photometric or psychological characteristics, it suffers from some of the same drawbacks as HSL and HSV: in particular, its lightness dimension differs from perceived lightness, because it forces colorful yellow, red, green, and blue into a plane.