I was admiring this rendition of the Mona Lisa from quasimondo's Flickr account. He says:
Combining circle packing with data visualization. The pie charts show the distribution of the dominant colors under the circle area.
The circle packing technique used here is a combination of an image segmentation with a distance transform and the first one who came up with it is John Balestrieri: www.flickr.com/photos/tinrocket/
I have traced it to an app called Percolator
How are such circle packings calculated? How are the pie charts calculated from the image?