It's 'The Dress' all over again.
The Best Illusion of The Year Contest is an annual event that does exactly what it says on the tin, and this year's winner was a colour perception illusion called Splitting Colors by Mark Vergeer that will give you a headache. It's all explained here (it's a lot of science which is equally confusing) but it's more fun to just sit back and have your mind blown.
This is hurting our heads.
The runner-up to 'Splitting Colours' was this Ambiguous Garage Roof by Kokichi Sugihara of Meiji University in Japan, and is just as brain melting.
You can check out the rest here, if your brain is still in one piece.
Via Metafilter