Different Color Wheels

Sir Issac Newton was the first to pass sunlight through a prism and thus split the light up into its colored components. The rainbow-colored light band coming out of the prism is called spectrum and the process of splitting up white light into colored light is called dispersion. A rainbow also arises from dispersion, i.e. the light is refracted by the little drops of water which float in the air. The following graphics show such a spectrum with the corresponding wavelengths (in nm):

 
The spectrum

The spectrum begins with red and ends with violet, magenta is missing. A rainbow lacks magenta because violet and red cannot touch. But when the light hits a magenta-colored object, violet and red are reflected and we then perceive it as magenta.
 
From da Vinci (1452-1519) to Newton (1642-1727), Goethe (1749-1832) and Munsel (1858-1918) up to Ostwald (1853-1932) and Itten (1888-1967), there were numerous attempts to create a scientific order system for colors that can be explained objectively. Newton was the first who used the spectral colors as basis for his color wheel. He drew a circle and arranged the spectral colors on it:

 
Newton's color wheel

 
Goethe's color wheel

The names of the colors are misleading and were not standardized at all in those days. Even today, there still is a great mess in naming colors. In one textbook the RGB-blue is called violet, and in another textbook magenta is called red. But most textbooks have in common that they use the symmetrical color wheel on which the RGB and CMY colors have an angular separation of 60°.
 
Following is the color wheel according to Johannes Itten:

 
Johannes Itten's color wheel

In a color textbook, you can find the following comment on Itten's color wheel:

"When Johannes Itten speaks of "violet" in his theory of colors, he means a color whose hue is very similar to our blue."

This comment tries to explain the deviations of Itten's color names from the symmetrical color wheel. In Itten's color wheel, yellow is opposed to violet, in the symmetrical color wheel, however, it is opposed to blue. Some think that this deviation is due to the misleading color names (more information about this topic on the following two pages).