The Commodore 64's "secret colours"

Commodore's C64 had a famously decisive, if drab set of 16 colors to choose from, a note of artistic intent amid the unthinking mathematical extremities of other 8-bit color palettes. But did you know there were secret colors? Aaron Bell writes up a discovery that blew his mind many years ago and which, 26 years later, he's finally figured out.

If you swap two colours rapidly enough - say at 50 or 60 frames per second - you can fool the eye into seeing something that isn't there. On a machine with sixteen colours, just one or two extra can add a lot to a scene. Since today we all live in the future and you are reading a fully programmable document on a supercomputer, let's try it.

The sad part is that the trick doesn't work for most pairings due to the obvious strobing/flickering effect it generates. But now wily coders can add a whole host of new grays to their vivid Commodore palettes. ("The tartan for the clan McPuke" is definitely the best description of the C64 palette I've ever read. I doubt it'll be topped.)