Copyright 2008 S.Monnier
Some space invaders, inspired by this wonderful website...
This pattern is constructed as follows. Take a square gird. In a limited region of this gird (here 5 by 5 squares), color the tiles randomly with two colors, with the requirment that the resulting design is symmetric with respect to the vertical axis. The resulting pattern is strongly reminiscent of Space Invaders, one of the first computer games.
As in most images, this pattern is then piled at different scales.