September 30, 2002
Neat visual illusion

Take a look at this image.

My first explanation is pretty obvious.. it's caused by the gradual changes in the colours and contrast in surrounding squares.

A friend suggested the checkerboard pattern is also at fault here..
To quote:

Our minds want to see the perfect idea of a checkerboard (alternate DIFFERENT colors) hinted at by the picture, so we are "not seeing" the filters applied to the picture like shadows or graduation of contrast that make the intensity the same as it hits our eyeball. The sense of a border is much stronger than the sense of absolute color values.

That explanation also makes perfect sense, in reality probably a combination of both.

Neat.

Original found by Steve.

Posted September 30, 2002 11:09 PM in Random
TrackBack URL for this entry: http://www.unix-girl.com/mt/mt-tb.cgi/175
Comments
On October 1, 2002 12:10 AM Dan Isaacs added:

I dunno. I covered all the areas except the two squares, and they still loked very different.

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On October 1, 2002 12:11 AM kasia added:

Pull out a graphics editor and have at it :)

I did.. they really are the same colour..

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On October 1, 2002 03:13 AM Dennis S.H. Andersen added:

Take a piece of paper. Make two small holes in it so if fits over the two squares. Place it on your screen, so that you only see the background color of the two squares (not the letters)... Voila! Thats how I did it :)

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On October 1, 2002 07:41 AM Dan Isaacs added:

I'll accept that. I just used my fingers. And Evolution has not yet panned out where covering optical illusions with ones fingers is concerned.

Or, God did not wish for me to cover optical illusions with my fingers.

Or, Evolution [b]has[/b] panned out, and I've just been left behind.

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On October 1, 2002 07:42 AM Dan Isaacs added:

Hmm. Whatta ya know. UBB code doesn't work. Must not post and eat cereal at same time.

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On October 1, 2002 02:23 PM Steve added:

Wow, this is for real. I cut out parts of both and moved them aside: they're the same color. Wow.

second image here

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On October 1, 2002 02:44 PM PopeMatt added:

I would guess that it's not the checkerboard that's at fault it's the suggestion of shadow. If I recall correctly, the way our brain perceives images tends to compensate for lighting conditions in order to more accurately determine the underlying color of the object (presumably a trait that helps one not be selected out due to varied lighting conditions while mushroom hunting). I perceive the shadowed dark square adjacent to A to be the same color as A and a uniform color across the surface even though I can see a color gradiant due to the "shadow" falling across it.

It would be interesting to experiment by modifying the shadow and shapes. If rather than squares you had smooth gradients (point sample the centers and blend) and the same perception of difference in color was achieved, then it would be more attributable to perception of shadow than any to a sense of contrasting border.

(yeah, I'll get around to trying that in about 6 months when I finish cleaning up this giant poo pile our idiot^H^H^H^H^H lead programmer has left behind)

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On October 1, 2002 03:29 PM Ron added:

I agree, its a good illusion! I have a question way off the topic though. Kasia, I saw your picture at www.unix-girl.com/images/kasia.jpg
& was wondering how long ago that picture was taken? Don't worry I am not a stalker. I checked & rechecked my posting, I know you hate acronyms so I didn't usa any.

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On October 1, 2002 05:09 PM Naladahc added:

Hmmm. Definitely has potential in the general digital color theory classes I give.

I'm surprised I never came across this before.

Thanks!

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On October 1, 2002 07:54 PM Steve added:

This delightful illusion is from Dr. Edward Adelson, Professor of Vision Science at MIT. His description of this illusion is here.

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On October 1, 2002 08:00 PM kasia added:

Cool! Thanks Steve.

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On November 14, 2002 11:14 AM manisha added:

ur site is very good.i want to know static illusion visual illusion dominance subordinate etc.

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On June 18, 2003 09:41 AM faget added:

I HATE YOU ALL YOU ARE ALL FUCKING FAGETS I SUCK MIKE GOLODS DICK EVERYNIGHT THIS IS HIS MOM

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