Dizzying effect Droste
The technical term for the illusions used in these photographs - "Droste effect". This name was the effect in 1904 in honor of, oddly enough, a package of cocoa brand Droste. Picture showing Droste effect, shows a smaller version of itself in a place where such a picture should appear. This smaller version, in turn, represents an even smaller version of itself in the same place, and so on ad infinitum. If you long to look into these pictures, you can watch until the dizziness.