The illusion above is called Splitting Colors by Mark Vergeer. You can read an explanation of it here. It was crowned the winner of the annual Best Illusion of the Year Contest for 2015. Coming in second was Ambiguous Garage Roof by Kokichi Sugihara of Meiji University in Japan.
See all top ten finalists in this year’s competition at the contest website. But first, prepare for your mind to be blown. Yes, that colored dress is in there. -via Metafilter