Sunday, December 11, 2011

Yes... I mean, No.

You might have seen this optical illusion. Step back from the screen and determine which side is angry, and which is happy. Then approach your computer, and ask the same question.


How do they do that?

Your visual system is tuned to certain spatial frequencies, so you tend not to notice image content of frequency higher or lower. I did an experiment and created my own version of this optical illusion. I started with these images.
Then I applied a lowpass filter to YES, and a highpass filter to NO. That gave me these images.



Adding them together gives this image...



Yes, your visual system acts as a filter (as does every optical system).

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