Type & Optical Illusions

Type Addicted is a typography book I refer to for inspiration. The coolest thing about the book has eluded me for quite some time now. I can’t believe I’ve never notice the great optical illusion on the cover. It was brought to my attention by a co-worker. Up close the cover is an unassuming pattern of triangles. When you view the Type Addicted cover from a few feet back the title of the book comes into focus. Below is a copy of the cover along with three other optical illusions that work on the same principal. Steps back a few feet and see for your self. Does anyone know the science behind them? Do you think outdoor advertising can make good use of this? As always chime in and let me know what you think.

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