I used voronoi cells to create cool effect images.
I generate a lot of points on the image.
For each pixel we calculate closest point and use color of this point on this coordinates.
Ta-da!
Also, I tried to implement some optimization: First algorithm was checking distance to every point doesn't matter is it close or far away, so I decided to divide image by 150x150 blocks.
Place your file to "input.jpg".
$ cd voronoi-image-processing
$ javac Main.java; java Main
And output will be on "output.png"