How was this achieved?

Not sure if this is the proper place for this thread, but anyway.

http://www.fox-company.com/

See the image transitions once the grid has formed. Can someone explain to me the basic concept behind that? Is there a way to break up an image at run time so it transitions in and out like that or would the image need to be broken up before hand (if so what would be the most efficient approach?).

Thanks.