Retinex theory of colour vision
Examples R/C anaglyphs
Other colour combinations can work for 3D, since the aim is to separate the right and left images but still see them about equal in brightness for the average human eye.
ColorCode© uses amber/blue. Amber (left) shows the colour and blue (right) shows the parallax. The colours are very realistic, . When seen without the glasses, ColorCode images look almost normal because the "ghosts" are yellow and blue, which seem less obvious than red/cyan ghosts.
Despite the excellent (but not perfect) colour rendition, ColorCode is not popular in the amateur 3D photographic community, as shown by the small size of the Flickr group for yellow/blue anaglyphs. Several commercial applications have been made in Europe.
The problems are a dark, out of focus blue image, but there are work-arounds as I describe here.
Like Spacespex filters, the dark blue right eye filter is disturbing, often compared with looking through a muddy window. Spectroscopy shows the blue filter is transmitting as much energy as the yellow filter, but human eyes have poor sensitivity to blue. As Dmytro Bezsmertnyy says, "You turn into a one eyed pirate".
The amber filter is dark, by adding grey, to try and make the left eye luminosity closer to right eye, but it still does not balance. Older people become less sensitive to blue light. Often old people cannot see through a K line (deep blue) solar telescope for example. Many 3D enthusiasts are old and this may contribute to the relative unpopularity of ColorCode.
The unfortunate result is Colorcode needs bright illumination. Viewing the computer with a bright LCD screen in a darkened room helps considerably. Fortunately, modern digital projectors are very bright.
(You can get the 3D goggles from ColorCode or from the people who actually manufacture them:
American Paper Optics (who also make IYF red/cyan filters)
ColorCode 3-D® was developed by the Tri-Delta Group at The Technical University of Denmark.