In a Voronoi diagram each coloured region is the set of all locations that are closer to one point on the screen than to any other point. In this Goofy Voronoi, 300 random points on the screen are chosen. The shrinking circles are the colours of the corresponding points in the Goofy picture (120 x 90).
The Voronoi code is by selim_tezel I have changed the colours. They come from the Goofy picture rather than being random.