A printing method that, when the image is viewed at different angles, the objects either look 3D or they change their appearance. Two or more views of a scene are printed on a thermoplastic sheet of lenticular (concave) lenses that look like parallel ridges (see below). In order to align the image to the lens array, specialized, high-quality lithographic presses that can be adjusted to fine tolerances are used. Dating back to the 1940s, millions of lenticular images have been printed on postcards, novelty items, political badges and religious scenes, as well as ads that change their message to the person walking by. Using multiple views, an image can be made to morph from one object into another. The lenticular printing method evolved into 3D display screens with the advantage of not requiring the viewer to wear eyeglasses (see lenticular 3D). See 3D visualization.