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  • Writer's pictureFrank DiGiovanni

The eyes have it

That phrase wasn't written because everyone was in agreement of anything in particular, nope. This time it is the eyes we will focus on in this post. Just a little eye humor for you.

Before we get into the fun portion of this post, we have to learn a little something first. Your eyes are one of the most incredible organ(s) in your body for they are the only organ directly connected to your brain. Yes, the fact you can feel the softness of your sock inside your shoe tells you that your brain is getting messages from your body but... that message of softness had to make its way from your toes, through your foot's nerves, up through your leg to your spinal cord and eventually to your brain, where your brain went "Yup, my socks are soft." What you are seeing while you read this is going directly from your eyes through your optic nerve to your brain, where your brain processes the image before passing it to the part of your brain in charge of language, where you've now understood what I've written.

Our friends from are credited with this excellent diagram of the eye below. And if you look closely on the right side of this diagram, the optic nerve at the back of the eyeball (dutifully sending visual messages to your brain every second you are awake).

With the other portions of your eye working properly, you are able to view the world around you. From the color of the sky to how far away something is from you, your eyes are a roughly one-inch globe with some very familiar parts to it. The black pupil dilates to increase or decrease the amount of light entering your eye. Your iris gives your eyes their color, are your irises brown/hazel (like mine and Caitlin's) or blue like Kristen's (our executive director)? Do you have green eyes? Or maybe you have heterochromia, where your irises are two different colors like the MLB Max Scherzer or actress Alice Eve? Maybe, you even know an animal that has two different colored eyes such as this cat; heterochromia is common in dogs like Dalmatians and Australian sheep dogs, and even seen in horses! Don't forget the sclera, or white portion of your eye and the lens that is squashed and squeezed as your focus on things. Plus there is the cornea, covering the exterior of the eye, protecting the eyeball itself.

Max Scherzer (courtesy; Alice Eve (courtesy; cat (CC BY 2.0. Keith Kissel/flickr)

Whatever color(s) you have, when you hear someone say that the "Windows are the eyes to the soul...", (for some say, the soul lives in the brain), you can probably understand that better because of the eyes. But eye color isn't important for us here, what is, is the ability to move them and focus them in the way we want. For to move our eyes, just like other parts of our body, we need muscles and the experts at Brimhall Eye Center share their knowledge of these muscles. "They are split into two primary groups: the recti muscles and the oblique muscles." And while they are fascinating in their own rights, I want you to read through the specifics, here. Suffice to say, these six muscles help you look from side to side, up and down but it is the ciliary body and the ciliary muscle in each of your eyes that allows you to focus on points near or far, which is exactly what we want when dealing with something called an "Autostereogram".

First, you may here of something called a "stereogram", which is the same TYPE of image we're going to talk about, but requiring a special device to help you see it. An autostereogram is a two-dimensional (2D) images with repeating patterns that hide an underlying three-dimensional (3D) image. You can think of it as an image hiding inside another. In order to make an autostereogram show itself, you need your ciliary muscles and sometimes, a fair bit of patience. This is because, typically when you're looking at one of these autostereogram images, your brain focuses on the image as a whole and not what maybe hiding. As your focus shifts "behind" the picture, the hidden one will reveal itself. Let's try one.

My grandfather taught me to work smarter and not harder. And in this case, I am going follow that advice. Rather than rewrite them, I'll send you to, on how to view them, if you're having trouble. Personally, I have the most success with the cross-eye method mentioned. Try them and see what works best for you on the image below.

The first is the parallel (also known as wall-eyed or wide-eyed) method. With the parallel viewing method, you have to focus your eyes somewhere behind the 2D pattern.

The second is the cross-eyed viewing method. With this viewing method, you have to converge ('cross') your eyes to focus in front of the 2D pattern. Most 3D images are constructed to be seen with the parallel viewing method. When viewing an image designed for parallel viewing correctly, the 3D shape will appear to pop out of the background. If you view it cross-eyed, the image will instead appear as a cut-out behind the 2D background and will be difficult to bring into focus.

So? Did you see it? <3

Most commonly referred to as "Magic Eye" pictures, these sorts of images have been around longer than you might imagine. In fact, the EARLY origins of these images begin in 1593! A man named Giambattista della Porta was said to have viewed the page of a book with one eye, then the opposite page with the opppsite eye. This process of viewing like this created something called "binocular rivalry" where the images are in competition with each other, rather than accommodation with each other, the latter being essential for properly viewing an autostereogram. 245 years would go by before Charles Wheatstone (in 1838) published examples of (image) cooperation, something called stereopsis (binocular depth perception). What he stumbled upon was the idea that two similar images, taken from different horizontal positions, could simulate depth in an image! 1844 would see David Brewster discover what he called the "wallpaper effect". To discover this effect, Brewster found himself staring at the repeating patterns on the wallpaper and varying the vergence (how crossed his eyes were while looking at the patterns) and noting what happened - the images seemed to elevate off the wallpaper.

Further, (1939) Boris Kompaneysky, published the first, random-dot stereogram, which contained a hand-drawn image of the face of Venus. In 1959, Bela Julesz, a vision scientist, psychologist, and MacArthur Fellow, invented random dot stereograms while working at Bell Laboratories. This happened as part of efforts at recognizing camouflaged objects from aerial pictures taken by spy planes! In 1970, and following Julesz footsteps, Japanese designer Masayuki Ito created a single image stereogram and in 1974, Swiss painter Alfons Schilling created a handmade single-image after creating more than one viewer and meeting with Julesz.

But it was finally in 1979 when a student of Julesz named Christopher Tyler would see these sorts of images start to become more widespread and popular. Tyler, Using an Apple II and BASIC computer language, and with the assistance of programmer Maureen Clarke, created the first black-and-white random-dot autostereogram. It would be over a decade before computer programmer Tom Baccei and artist Cheri Smith created the first color random-dot autostereograms, later marketed as Magic Eye books. As of this writing, there have been an estimated 25 million copies worldwide and published in over 20 languages! Don't you wish you had been the one to patent those books?!

If you'd like to get into the mathematics and further in-depth understanding about the difference between Random-dot, Simple wallpaper and Depth maps, I encourage you to use the Wikipedia page on Autostereograms, but please remember: if you know how to code, you can make a Wikipedia page say whatever you want, so use it as a starting place and go from there. The "What are autostereograms?" page at is also loaded with great information about them.

With all that being said, I've accumulated a few of these autostereograms for you to try. I have included two which have the same hidden image so you can see the difference between random-dot and wallpaper stereograms.

All images below are from Wikimedia commons.

The 3D (sea creature) in this random-dot autostereogram has a smooth, round shape due to the use of depth map with smooth gradient.

The same sea creature as above. This random dot autostereogram features a raised (sea creature) with fine gradient on a flat background.

A type of wallpaper autostereogram featuring 3D objects instead of flat patterns.

You may need these to view certain movies. A Single Image Random Dot Autostereogram

Mapped Textured Stereogram (MTS) where a textural image is mapped onto a depth-map rather than mapping a random pattern.

One last thing, if you're interested in knowing more, here are a few places to start.

Happy viewing and good luck in your search for what is hiding in some of these

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