All of the above images are 3-dimensional lenticular images. They have an apparent depth of 6 to 18 inches or more depending on the image and its width, although the print with its laminated lens is only about 1/8 inch thick! You can read/download an pdf article briefly describing the history and process of lenticular art.

It is hard to visualize lenticular images when you are looking at a static web version, slide, etc. Think of it like a 3-dimensional movie snip you would see wearing 3-d glasses! Below is an Flash animation of one of the "Sound Waves" panels which might help you imagine the effect of viewing a lenticular panel. (You can download the Flash player here.)