Café Wall Illusion

There are only straight lines in this picture, but because of the placement of the black and white tiles, the horizontal lines seem to be wavy. The name of this illusion is no coincidence : this was first noticed on the black and white tiles of a café wall in Bristol. (Probably a trick to make people believe they needed a drink). This is also known as the Muensterberg figure. No, I don't know why.

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