Mad optical illusion!

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Tigger

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Oct 24, 2001
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opti.jpg


Mad or what - I even checked it in photoshop cos I didn't believe it!!!!
 
I

ilovepiano

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Jul 9, 2002
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er... What? The two squares A & B don't look to be the same colour to me. And what's with that green thing? :|
 
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ilovepiano

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Sorry if I'm being realy thick... Am I meant to be looking at the squares or the actual letters A & B? I can see that the letters are the same colour, but it looks wierd coz of the shadow, but there's no way the squares are the same! :p
 
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petemc808

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Aug 18, 2001
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that is fecking mad!! :S

not saying i didn't beleive you guys but had to check it out for myself with photodraw and both squares are exactly the same shade of grey.

if fact what am i saying, i blatanly didn't beleive they where the same because they look so obviously different but they fecking are.

now thats truely amazing m8!!!
 
R

Red Mancunian

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Chav-ville Droylsden, innit!
Wow, that does your head in when you work out what your brain is doing to confuse you...

Top one fella (I even had to check the colours in, ahem, 'Microsoft Paint', cos I don't have any of them fancy photoshop thingies!).

I did psychology in college all those years ago, and I used to LURVE perception and stuff... well fascinating.

Nice one!

:crazy: <---my eyes now!
 
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ilovepiano

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Oh I've had enough of this bullshit. :p There's no way in the world that squares A & B are the same colour. I know this because I can see that A is dark grey and B is light grey. Even though B is in a shadow and is darker than the other light grey squares, it doesn't make it as dark as A.
What are you people on? ;)
 
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grad

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:confused: well it'd be a shite illusion if they looked the same..

here's what's happening;

(by 'visual system' they mean your visual system..)

The visual system needs to determine the color of objects in the world. In this case the problem is to determine the gray shade of the checks on the floor. Just measuring the light coming from a surface (the luminance) is not enough: a cast shadow will dim a surface, so that a white surface in shadow may be reflecting less light than a black surface in full light. The visual system uses several tricks to determine where the shadows are and how to compensate for them, in order to determine the shade of gray "paint" that belongs to the surface.

The first trick is based on local contrast. In shadow or not, a check that is lighter than its neighboring checks is probably lighter than average, and vice versa. In the figure, the light check in shadow is surrounded by darker checks. Thus, even though the check is physically dark, it is light when compared to its neighbors. The dark checks outside the shadow, conversely, are surrounded by lighter checks, so they look dark by comparison.

A second trick is based on the fact that shadows often have soft edges, while paint boundaries (like the checks) often have sharp edges. The visual system tends to ignore gradual changes in light level, so that it can determine the color of the surfaces without being misled by shadows. In this figure, the shadow looks like a shadow, both because it is fuzzy and because the shadow casting object is visible.

The "paintness" of the checks is aided by the form of the "X-junctions" formed by 4 abutting checks. This type of junction is usually a signal that all the edges should be interpreted as changes in surface color rather than in terms of shadows or lighting.

As with many so-called illusions, this effect really demonstrates the success rather than the failure of the visual system. The visual system is not very good at being a physical light meter, but that is not its purpose. The important task is to break the image information down into meaningful components, and thereby perceive the nature of the objects in view.



Sweet, open paint shop pro, easiest thing is pick the little dropper icon on the left, then left click one square, then right click the other..this puts the colours next to each other on the colour palette on the right & they are the same.
 


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