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I'm confused? Don't they all require crossing your eyes? I've gone through about 20 on this site and "solved" them by crossing my eyes and locking the patterns together.

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Most of autostereograms are meant to be seen wall-eyed, instead of cross-eyed [0]. With wall-eye, you shift the convergent point being what you're seeing, while with cross-eye you shift it before.

So it creates the exact opposite 3d. Watching a stereogram meant to be seeing wall-eyed, cross-eyeing you'll see an upside down 3d. Some stereogram are mean to be seen cross-eyed though, which is considered easier to see.

[0]: https://en.wikipedia.org/wiki/Autostereogram

It wont’t turn the image upside down, but the depth will be inverted, so what is meant to jut out at you will become a trough away from you.

"the depth will be inverted" better describes it indeed. Thanks clarifying it!

> With wall-eye, you shift the convergent point being what you're seeing,

Here "being" probably should have said "behind".

https://hidden-3d.com/stereogram_theory.php

Either can look in front or behind.

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