Nearly eight hours in the making, here it is: all the 24-bit colors in a tasteful, tilable fractal arrangement — 16million.png.gz (1 megabyte). And since Mads asked for it, the Python sourcecode: two files.
Another way to flatten the color cube is by traversing both the cube and the square with Hilbert curves, and continuously mapping one to the other. I’ll try that, one of these weeks.
Hours? I must have been still using the inside-out approach. Now it takes under three minutes – after two hardware upgrades, but still.