Octarine?

The average human eye has three types of cone cells, each of which is sensitive to a different wavelength range of visible light. The difference in the relative signal from the three cones allows us to distinguish colors. Unfortunately, since these sensitivity ranges overlap, there are some combinations of signals from the cones that can't be created by light emitted from a real object. These are the so-called "imaginary colors". However, by selectively overstimulating one or more types of cone, we can still perceive these colors; this is the principle behind the Eclipse of Titan, an optical illusion which produces both a green and a cyan that don't otherwise appear in nature. (Similar effects can be seen in the Eclipses of Mars, Neptune, and Triton.) [more inside]
posted by Upton O'Good on May 10, 2010 - 64 comments