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Hello fellow investigators

I have two question about optical illusions

1) A photo mosaic is something like this http://i.stack.imgur.com/Pzplp.png

What are the optical principles behind our eye merging the many tiny images into a large coherent one?

2)Are there etiological explanations of optical illusions in general - by this I mean can it be explained why image inputs get parsed in 'wrong' ways by the eye/brain, whys does the parser get confused?

Thanks for your time

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Not really physics, but cognitive science, isn't this? – dmckee♦ Jul 20 '12 at 16:50
I though there is an optics explanation if one abstracted the eye through a model. – Daniel Bilar Jul 20 '12 at 17:54
There aren't many tiny images entering your eye - there is just a set of points. If you zoomed out so that it was only one pixel/image how is this different from any other picture? The same in "real life" if you stand far enough away so that you only see each picture as a dot - how is this different from you merging all the microscopic details of a brush stroke into a single dot? – Martin Beckett Jul 20 '12 at 18:57

closed as off topic by Qmechanic♦, Manishearth♦, dmckee♦ Nov 26 '12 at 13:46

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1 Answer

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1) Photomosaics work because the eye has limited resolution (or visual acuity), around 1 arcminute for one with 20/20 vision. When seen from a large enough distance, the high-frequency information in each image gets averaged, leaving the low-frequency information. However, the creator of the photomosaic has intentionally arranged the sub-images so that the combined low-frequency information of all the sub-images forms a different image.

2) It depends on the illusion — different ones capitalise on different physiological and psychological effects. The articles for each illusion in Wikipedia often describes their respective effects.

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