The human eye can distinguish about 10 million different colors, but most of them lie outside the gamut of this image.

Created with the following very short program written in Chipmunk Basic:

10forx=0to999
20fory=0to999
30z=int(y/100)*10+int(x/100)
40graphicscolorx,y,z' x=red y=green z=blue
50psetx,y
60nexty,x

The value for red changes cyclically in the left-right axis, in ten periods of a sawtooth wave, going from 0 to 100% in 1% increments per pixel; the value for green changes cyclically in the vertical axis in the same way; while the value for blue changes by 1% in each small, 100 by 100 pixel square, moving across then down, as seen when the channels are separated below. Imagine putting all the 100 by 100 pixel squares on top of each other — you would then have a cube, 100 px each side, with R, G, and B along the x, y, and z coordinates, each changing 1% for every step.

In the above example blue changes by 1% in each small square of 100 by 100 pixels, but it could just as well have been red or green. Below are three squares, the top has red changing in each small square, the middle one changes are in green and the bottom is blue. Each of the large squares contain the same set of colors, but in different arrangements.

All the following user names refer to the English Wikipedia.