Click here to run a visualization in your web browser.
Part of the Coins project.
Cryptocurrencies such as Bitcoin use a “proof of work” system to prevent abuse.
Artworks are proofs of aesthetic work.
The difficulty can be varied by altering the size and blur of the pixmap. Or by only allowing particular detected face bounds rectangles to be used a set number of times.
You can download the source here: https://gitorious.org/robmyers/coins/.