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welcome to stereograms Page
What is a STEREOGRAM? TOP
How do stereograms work?
In normal vision, when looking at a page of text for example, both eyes look at exactly the same place. With a flat page both eyes see practically the same thing and hence the brain concludes that the page is indeed flat. Now a stereogram picture is basically made up of a pattern which repeats across the width of the page. When you diverge your eyes to "see" it each looks at adjacent repeats of the pattern, but the brain is fooled into believing that both eyes are still looking at exactly the same thing. Since the pattern is not just copied but is subtly distorted on each repeat, (in accordance with the three dimensional image represented), the two eyes see slightly different images. At this point, human perception takes over and the brain concludes that the differing images arise from looking at a three dimensional object, whose form it decodes in an instant. Hence the 3D illusion occurs.
