The Principle of 3D Lenticular
The principle of bionics tell us that our eyes see in three dimension, because our two eyes are separated horizontally, the image that each eye sees will be different. The difference or displacement determines the depth of object that we see. This is the stereo vision principle. “When our two eyes see two images from two different angles, we see the 3D effect as the real world”.
A Lenticular print is an image that has been sliced into strips which are then interlaced with one or more other images. The image is then printed on the back of a series of prism-like lenses. The lenses are lined up with each image interlace, this image line's location is determined by the observer's view angle. If an image is printed at each lens interval, the observer will see different images when looking from different angles, when light reflected off each strip is reflected in a slightly different direction, but all strips from the same image are sent in the same direction (parallel). The brain automatically interprets this displacement as depth.
The end result is that a single eye/camera looking at the print will see a single whole image, but another eye/camera at different position will see a different image because of the different angle of view. How different depends on the lenses used, the number of original images, and how different the original images were from each other.
For example stereo films have two images lighted by two vertical polarized lights, and a polarized glass is used to look at them. Each eye will see only one image. Some printable lenticular lens sheets can also be used to create this effect. As previously discussed, you see different image groove lines from different angles. If we place a lenticular vertical lens, where its grooves are perpendicular to the horizontal plane of our eyes, the different view angle of the two eyes will see two different image lines. When these two different image lines correspond to one stereoscopic image(consisting of two images), we will see a 3D effect.
In order to achieve a even better effect, we can use multiple images. Because our eyes are horizontal, and the lenticular groove is vertical the lenticular image must be interlaced (combined) from vertical lines of stereo images.