[nelliott]

Look at this image

If you open the pic up in photoshop, you'll see that the two squares A and B are actually the same colour - weird eh??

[scaught]

maybe its just the LCD on my work computer, but theres no way those 2 are the same color.

[BRussell]

Very nice. They definitely are the same color.

To believe it, you have to open up two of the document and put the two squares side by side. You'll never believe it otherwise.

[MacAgent]

They are.

[ckohler]

This image must be making rounds on the net today. I came across it for the first time on another message board earlier.

[Developer]

Great illusion! Thanks.

[arrested502]

Pretty cool. They both share the same CMYK or RGB values.

C = 58%
M = 50%
Y = 49%
K = 17%

R = 117%
G = 117%
B = 117%

To find this in photoshop you just need to use the eyedropper tool, then jot down the percentages from the color palette. I also made a new layer and filled a small square next to color A and filled it with the color from color B. Exactly the same.

[BRussell]

This reminded me of my favorite illusion.



The table tops are exactly the same size and shape.

[ckohler]

A friend sent me this link which includes the explanation of this illusion by the creator.

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.

[ink]

If you squint hard enough, you'll see that they are the same shade without the use of photoshop. Very wierd.

[MindFad]

That's awesome. I had to open up Photoshop just to see.

[mr_sonicblue]

For those without Photoshop, you can use the Digital Color Meter in OS X's utility folder.

[scaught]

Originally posted by BRussell:
This reminded me of my favorite illusion.



The table tops are exactly the same size and shape.

its a good thing noone walked into my office just now to see me measuring those 2 tables against my LCD with a ruler.