Phantogram (optical illusion)
Phantograms, also known as Phantaglyphs, Op-Ups, free-standing anaglyphs, levitated images, and book anaglyphs, are a form of optical illusion. Phantograms use perspectival anamorphosis to produce a 2D image that is distorted in a particular way so as to appear, to a viewer at a particular vantage point, three-dimensional, standing above or recessed into a flat surface.
Source: Wikipedia — Phantogram (optical illusion) (CC BY-SA 4.0)