I'm revisiting my allRGB solution six years later, taking the same premise (mapping a hamiltonian cycle in the colors to a hamiltonian cycle in the pixels) but different approaches to the spanning tree, and a full rewrite of the code.
In this example, I like the contrast between the lights and darks of similar hues, and how many of the most saturated colors are near the center. I see a green and yellow mountainside with a fire erupting in reds, oranges, and pinks, casting in a shadow in purples, pinks and blues to the right.
