Lenticular Pictures are images with the illusion of depth. The image appears to be either animated or in 3D (not a flat image, but appears to pop in or out of the picture). When flipping the image slightly from side to side, the image appears to "move" or change. This technology was introduced in the 1940's but has improved a lot since its time. The image is printed to give a stereoscopic effect. It has a smaller viewing angle so each eye is tricked into thinking the image is 3-dimensional without using any special 3D viewing glasses.