Saturday, May 24, 2008

Squaring the Diamond

Look at this image at your usual distance from your computer, and then from across the room. Does the image look different when you see it close up vs. far away? (If you don’t feel like getting out of your chair, you can get the same effect by scrunching up your eyes or, for those who wear glasses, by removing them.)

You should get two different impressions of the image. When you are close and the image is in focus, you should see horizontally striped diamonds on a field of blurry vertically striped diamonds. When you are far away (or if you have scrunched up your eyes or removed your glasses), you should see a field of squares.

Why does this happen? We often take it for granted that we see the world at different scales. Look at the page that you are reading: you can probably perceive fine details (say, letters and words), broader features (like the shape of the paragraph), and large features (the outline of the page).

The amount of information at each of these scales changes as we move about the world. When you are far away from your computer monitor, you can’t make out letters or words because they are too small to see. But as you move closer, the letters and words become bigger, and (voila!) this new information becomes part of your perceptual world.

Our ability to adjust to these changes in size is helped considerably because, in the real world, objects tend to scale together: zoom out, you see the page; zoom in and you see words on the page. As you zoom, a word on the page gets bigger or smaller at the same rate as the other words.

“Squaring the Diamond” is compelling (at least to me) because it seems to violate this basic assumption about how objects scale in the physical world.

The display is composed of blurry diamonds and regular (a/k/a non-blurry) diamonds. When you zoom out, the diamonds combine to form a field of squares; but when you zoom in, you can see detail only in the diamonds that have not been blurred. Unlike the non-blurry diamonds and the words on this page, the blurry diamonds do not gain more detail as you move toward them because the blurry diamonds do not contain fine detail (in vision science circles, “fine detail” is known as high spatial frequency information). The result is that your perception of the field of squares breaks apart when you are near enough to see the fine detail in the non-blurry diamonds.

The buttons in the display allow you to blur and unblur the sets of diamonds. Click on the buttons, and see what you can find out about the image. Notice that you see squares when the horizontal and vertical diamonds are both blurred, and when both are unblurred.

The principle is similar to Schyns and Oliva’s hybrid images (Aude Oliva’s gallery of hybrid images is really worth seeing; here is a link to an article about one of their hybrid images: Dr. Angry and Mr. Smile).


Will said...

Terrific! I recently saw the Marilyn Monroe/Albert Einstein hybrid for the first time, and I was wondering how it worked. I thought it might be a trick of the monitor somehow, but the effect persists when the image is printed out as well.

Unknown said...

Squinting works too.

Anonymous said...

I've noticed that blinking reasonably quickly also works.

affordable web design said...

Is the surrealism art influenced by the optics illusions ?

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