Lenticulars images make the dream of every fan of stereoscpy come true since they restore depth information of a scene without the need of any viewer or any free-viewing techniques.

Is it a new technology ? As usual, no, even if it is not so much old as stereoscopy.

Probabily, all of us have had in our hands those shagreened pictures with those very dense parallel lines in which objects seem to move when you rotate the picture itself. These are lenticular pictures.

The principle is simple and ingenious at the same time. Just to simplify things, let's suppose to have two distinct pictures even if the same principle applies to an higher number of images.

Left image	Right image

Each of the two images is split into slices as in the following picture.

Splitting of the images

The slices of the two images are then put side-by-side alternating one from the left image with the related slice from the right image thus obtaining the following.

Ricomposing the slices in the final image

Slices with the red number belong to the left image; those with cyan are instead from the right image.

A transparent PET G sheet is then applied over the resulting image so that, due to its physical characteristics and to the different angle-shots, our eyes can see only one of the two images; through the tuning of some parameters (number of the distinct images, width of the slices, ..) it is possible, then, to have the left eyes looking only at the images with the red numbers and the right eyes only at those with the cyan numbers. And, what if, by chance, the two images are just a stereoscopic pair ? Well, congrats, from the plane sheet absolutely still (like a drawing) a wonderful three-dimensional picture will stand up and you'll understand how easy is to cheat our brain.

Obviously, we have simplified some aspects. For instance, the slices should be very narrow so that even hundred of them can fill a inch (2,54 cm): technically, we say the image is composed by x (number of slices) lpi (lines per inch).