A stylised version of the channel in Waterfall with ambiguous 3-dimensional detail addedThe Penrose triangleAn example of how an object could appear to be invisible through the use of mirrors
An optical illusion. Square A is exactly the same shade of grey as square B. See Same color illusion
The Scintillating grid illusion or Hermann grid illusion. Dark spots seem to appear and disappear very quickly at the intersections
Simultaneous Contrast Illusion. The grey bar is the same shade throughout
An optical illusion. The two circles seem to move when the viewer's head is moving forwards and backwards while looking at the black dot.