Attribution: The original uploader was LosHawlos at German Wikipedia. Later versions were uploaded by Mr. Anderson at de.wikipedia., CC BY-SA 3.0, via Wikimedia Commons.
A stereogram is a picture within a picture. The creator has cleverly hidden a 3D image inside an unusual looking 2D image. The brain can create the illusion of depth when you learn how to view the stereogram correctly.
For information on how to see the effect, please visit the Wikipedia article on Autostereograms.
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