[AllenG (OP)]

That's Einsteine right?  Now get up and look at the image from across the room--Marilyn.

How does this optical illusion work?

[RD]

Now get up and look at the image from across the room

If you are too lazy to get up, make the display smaller ...

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Squinting also helps.

[neilep]

That's Einsteine right?  Now get up and look at the image from across the room--Marilyn.

How does this optical illusion work?

Hey that's kewl Allen !!


It's a focus thing yes ?....lets hope we get a full explanation !

[lightarrow]

That's Einsteine right?  Now get up and look at the image from across the room--Marilyn.

How does this optical illusion work?

Hey that's kewl Allen !!


It's a focus thing yes ?....lets hope we get a full explanation !

Yes, Neil, it's a focus thing, infact this great picture was also on the magazine "Focus" (italian version, at least) some times ago  []
Their explanation, for what I can remember (I can forget something): it's a matter of "spatial frequencies". The Einstein' face has sharp and thin contours while the Marilyn's face has blurred contours. From low distance we see the sharp contours, from greater distances we can only see the blurred ones. The first picture has higher spatial frequencies than the second, in the Fourier transform.