How to View Stereograms and Viewing Practice(C) 1999 by Gene Levine
This page is intended to guide visitors that have never seen stereogramic effects and those viewers who may be a bit rusty. You may want to first read the About Stereograms page to get an idea of what you are about here. If you can see the 3D effect in the images below, you will also be able to view hidden-image type stereogram.
Some people see the effect right away, others can spend a few days. I've observed that the greater majority may need fifteen to thirty minutes. Please don't be discouraged if you can't visualize the effects right away. After all–what you are doing is overcoming a lifetime habit of viewing everything with "normal" stereo-vision: that which gives us a sense of depth in in our everyday viewing of the world. (Fig. 1)
If you ordinarily wear glasses to read off your monitor's screen, you will likely need them here. I have found that single lens glasses (as opposed to bi/tri focal, or progressive lenses) work best. Be sure to view straight on as possible.
First: let's try a visual aid. After that are practices for viewing without aid.
By placing a cardboard between your eyes (Fig, 2) you cannot use normal or cross-eyed vision. Instead, you are forced into parallel vision which is just what we need for Color Stereo stereograms.
A cardboard about 8 x 11 inches.
I have illustrated a cut-out for nose and glasses, but none is necessary.
Below is a stereo-pair image. Place cardboard directly in middle of pair, as illustrated in Fig. 2. Now place other end of cardboard between your eyes. Disregard focusing, for now.
If alignments are good, you should see only one image. Now relax your eyes, and slowly bring things into focus pulling your head back. Remember, you do not think you see a 3-D effect--you will know for sure. When you are sure, hold that focus and remove cardboard. You should now see three images: the one in the middle containing the 3-D effects. Congratulations, you are now viewing an autostereogram as it should be seen.
Below are practices without aids. The only thing you'll need here is a monitor and two eyes.
Let go the normal way you focus on something on a page. Let the eyes relax.
Practice # 1
o . . . . . . . . . . . o
Is that it? Two zeros?
What you want to do here is have your mind process these two objects until they appear as three. Let the eyes relax, and move your head forward or away until three zeros appear clearly. Your primary inclination is to focus on the above two objects as is normal. But now, look behind them; look into the inside depths of your monitor and forget about focusing. Try this for awhile, until you gradually see the three zeros.
You can also practice this with two dots, a couple inches apart, on a piece of paper. Try staring through the paper at a space a few feet behind it.
When you see a non-existent object appear between the two existing ones, you have mastered the basis of the Stereo Pair. It is the center object where the 3D effect takes place. This is the crux of all autostereograms (stereograms that work withut aids.)
So where does that center image come from?
It's helpful to remember that visual perception happens in the brain--not the eyes. What we're doing here, is fooling the brain. The eyes are feeding it visual information as usual, but not in the usual manner. The mind gives us a middle object. And if you introduce some subtle offsets into two otherwise similar objects, the mind will perceive the famous 3D effect we're here for.
Practice # 2
0 . . . . . .. . . . . . . 0 . . . . . .. . . . . . . 0
If you view three objects as an autostereogram, you should perceive four objects. Four objects will look as if there are five, etc, etc.
Practice # 3
And now for some 3D.
Between these two objects, another object should appear with the smaller square floating over the larger.
Practice # 4 Still cant see it?
Pull back, and focus normally on the center object of the three, below. Now lean slowly forward into the screen holding that focus until it is broken or you see four objects, clearly.
I hope this page has helped. Master these practices, and you should have no problem moving on to full fledged autostereograms.
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