The Same Color Illusion

anniemcu · Post by **anniemcu** » Mon Jul 16, 2007 10:21 pm

This one is especially hard to believe, at least for me, but it is indeed the same color. I did a cut and paste overlay to be sure, and it's precisely the same. Amazing - and I already knew a good deal about the illusion effects when light and dark are interspersed... still got me though.

HampshireWhistler · Post by **HampshireWhistler** » Tue Jul 17, 2007 5:35 am

I don't get it

Is the green actually gray or something?

MarcusR · Post by **MarcusR** » Tue Jul 17, 2007 5:40 am

HampshireWhistler wrote:I don't get it Is the green actually gray or something?

Square A is the same color as square B.
Click the picture above if you are in doubt, and you end up here:
http://antwrp.gsfc.nasa.gov/apod/ap070717.html

Nice one Denny, this is one of the better same color illusions I have seen.
/MarcusR

izzarina · Post by **izzarina** » Tue Jul 17, 2007 6:14 am

HampshireWhistler wrote:I don't get it Is the green actually gray or something?

One thing to remember when dealing with a picture that Denny has posted...ALWAYS click on the picture before asking questions..all will be revealed

And hey! HW, you're almost at 100 posts! Getting up there, aren't you?

hathair_bláth · Post by **hathair_bláth** » Tue Jul 17, 2007 6:38 am

Denny's messing with my mind!

emmline · Post by **emmline** » Tue Jul 17, 2007 6:48 am

I had to stick little post-its to the screen to see it, but sure enough.

One of the art classes I took in college was "color." Among the projects we did was creating small montages in which we were to make two different colors appear to be the same, and make two occurrences of the same color appear to be different.
There were varying degrees of success.

djm · Post by **djm** » Tue Jul 17, 2007 7:01 am

Denny, my eyes
Tell me what is wrong
Was I unwise
To leave them open for so long

djm

(for Jackson Browne fans

)

Doug_Tipple · Post by **Doug_Tipple** » Tue Jul 17, 2007 7:16 am

Yes, as humans, we can easily be deceived about a lot of things, and most of them we can only discuss in the rubber room. The checkerboard optical illusion of color differences demonstrates that we (our brains) make judgements about color by the colors that surround the color in question. The colored square, when surrounded by darker squares, will appear to be lighter in color than the same colored square surrounded by lighter-colored squares. Interior decorators need to be mindful of such phenomena when designing the color combinations for a room. For example, an upholstered chair that will look just right in a room with yellow walls may look simply awful in a room with green walls.

Wanderer · Post by **Wanderer** » Tue Jul 17, 2007 7:36 am

I made a short video clip that easily demonstrates that A and B are indeed the same color. Because I'm a nerd that way.

http://www.tinwhistler.com/misc/illusion.avi

fearfaoin · Post by **fearfaoin** » Tue Jul 17, 2007 7:43 am

I was following a link from the APOD site, and I happened upon
this video on youtube. It's a neat CGI project playing around with
common graphical illusions.

http://youtube.com/watch?v=WX_JfsWI8ds

Wombat · Post by **Wombat** » Tue Jul 17, 2007 10:37 am

That's a great illusion. Illustrates the 'active' component in colour perception really well.

The perceived difference in shade between A and B is wholly a matter of brightness I think; chroma and saturation don't seem to play a role, certainly chroma doesn't. Does anybody know of examples of illusions like this which involve misperceptions of chroma?

Cynth · Post by **Cynth** » Tue Jul 17, 2007 10:58 am

Wanderer wrote:I made a short video clip that easily demonstrates that A and B are indeed the same color. Because I'm a nerd that way.

http://www.tinwhistler.com/misc/illusion.avi

That was very neat. I was going to use emmline's method but I couldn't find any post it notes, so this convinced me. It is still hard for me to believe they are the same, even though I know they are.

Doug_Tipple · Post by **Doug_Tipple** » Tue Jul 17, 2007 11:25 am

Cynth wrote:
Wanderer wrote:I made a short video clip that easily demonstrates that A and B are indeed the same color. Because I'm a nerd that way.

http://www.tinwhistler.com/misc/illusion.avi
That was very neat. I was going to use emmline's method but I couldn't find any post it notes, so this convinced me. It is still hard for me to believe they are the same, even though I know they are.

Cynth, click on the photo for the Astronomy Pic of the Day, and below the photo there is a link to verify that, indeed, the two squares that appear different in color are the same color. Their demonstration by connecting the two squares seems visually convincing to me.

djm · Post by **djm** » Tue Jul 17, 2007 11:44 am

The demo on the apod site didn't work for me initially. I could clearly see a gradation of the grey tones in the solid line they drew between the A and B squares. It wasn't until I blocked out the mitigating shadowing on either side that I could finally see that A and B were the same shade.

From the same apod page, there are a couple of links at the bottom:

The first takes you to a YerTube film that deals a bit with chroma phenomena: http://www.youtube.com/watch?v=w8Zz05t19dg

The second takes you to a site with examples and explanations of many illusions: http://www.michaelbach.de/ot/ I tried to get through the tour but was starting to get a headache.

djm