What is lenticular?
Lenticular is an adjective used to describe the technology as the formation of special effects requires a special transparent (plastic or glass) plate, named "lenticular sheet"---- one side embossed, or extruded, with tiny rows of convex "lens" and the other side basically flat.
One can feel three-dimensional with parallax (The difference between the images his or her left and right eyes). Lenticular technology creates three-dimensional images using the images viewed by the left eye and that viewed by the right eye through a convex lens (in semi cylindrical shape).
So, such a special image effect can be obtained just by placing the lenticular lens on an ordinary printed matter, on which the image (called "interlaced image") is processed by special 3D software for lenticular.