I used similar software that I previously used in the High Quality Wedding Render
This one took about 4 days to render (30 iterations of optimal random permutations of 32 pixels).
The color distance here was calculated by YCrBr with a 4X multiplier on Y (luminance).
The colors are too hot in my opinion. The algorithm is ignorant of the perceptual importance of neighboring pixels and what a selection of pixels really gives to the perception of an image. Ignorant of information etc.
Original Mona Lisa from Wikipedia that was cropped: http://churchturing.org/y/Mona_Lisa-4096.png
permuter Mona-Lisa.jpg 32
|Dimensions||4,096 × 4,096|