How does stereo imaging work? As in autostereograms or stereograms.

Question

I googled autostereograms to see how it works and it brought me to stereo imaging and no matter what I read online, I could not understand it so explain like im 5 please.

In: Biology

Answer 1

Part of how your brain does depth perception is by comparing the two different images from your eyes and finding differences in how things overlap. Close things need to shift more to overlap perfectly and far things need to shift less.

Now this all happens automatically and your brain doesn’t actually care what the overlapping things look like. It just tries to find matching sections.

Autostereograms use a bit of trickiness that uses repeating patterns to avoid needing two different images. The brain sees a bit from your left eye that looks similar to a thing from your right eye. But they are different sections of the repeating pattern. But the brain doesn’t know that subconsciously so the depth perception logic just assumes that the two different sections are really the same section cause it’s not paid enough to care.
From there it’s carefully shifting different parts of the repeating pattern left and right to mimick how much shift there would be in a normal image.

Diagram for clarity:

http://www.techmind.org/stereo/geometry.gif

Answer 2

We see in 3 dimensions because our eyes give us two views of the same picture. Our brain can calculate how are far something is away based on how similar both eyes pictures are. (You can do that math on paper too, calculating the height of a triangle from the two angles and the distance between your eyes)

In a stereogram two pictures are printed, one for each eye, that Show the same scene from slightly different angles. So if look at it from the correct distance our brain will do it’s magic and calculate a 3D image from it. (If you manage to turn off your eyes natural focus on a point of the paper)

In a autostereogram they only give you one picture, and there is basically a hidden stereogram in it, that you can only see if you look at it from the correct distance and don’t focus your eyes on a single point.