Part B: A Theory of Kinetic Color (Home)
5c. Hard and Soft Color Changes
When light sources are additively combined, color changes are most accurately mapped on a chromaticity diagram*. A color wheel is adequate, and I prefer a color wheel that mimics the color arrangement on the Chromaticity Diagram.
Hard changes occur between complementary or nearly complementary colors. When cross-faded, white or near white appears due to additive mixing between the end colors.
Soft changes occur between adjacent colors. A spectrum rotation around the color wheel consists of soft changes through the entire range of colors.
5d. Parallel and Opposite Motion