Have you ever faced those strange images in which (so they tell you) there are hidden 3D drawings? Well, if you didn’t know before, I’ll tell you now: they’re called stereograms and they have a rational explanation.
Although they seem to come out of a magician’s top hat, these images are nothing more than very well achieved optical illusions. To make them you need a lot of knowledge, not everyone is capable of generating one (although there are several websites that do allow it).
How do they work
A stereogram is basically a three-dimensional image hidden in a two-dimensional one. But how is this achieved?
It actually happens because of the way our eyes and brain build images. Whenever we look at something, each of our eyes captures a slightly different image. If you want to try this, try closing one eye first, then the other. You will see that things look a little different depending on which eye you look with.
The brain processes and superimposes the images collected by each of the eyes, and thus obtains volumes and distances.
Stereograms hide in their pattern two similar images with slight differences. These are placed in such a way that when the brain interprets them, it sees those differences as volumes and depths.
What does a stereogram look like?
There are different techniques for viewing stereograms. But the general slogan is to try not to fix our eyes on the two-dimensional image, so that we can capture the perspective and discover the three-dimensional.
- The trick is to stare at a point in the image, as if you wanted to see through it. But of course, this is not easy to achieve, because we are forcing our eyes and brain to do something different than what it is used to.
Therefore, seeing stereograms requires a little patience and a lot of training.
- A good method to see them is to keep the image at a distance of 40-50 cm and fix our eyes on something that is another 40-50 cm behind it, although there are those who focus it at infinity. When the view is fixed from behind and, as a consequence, the stereogram is out of focus, we must move our gaze over the texture but without changing the focus and leave our sight lost until the 3D image appears.
If you can see some depth effect, you’re on the right track. Keep practicing!
Cross vision stereograms
If you can’t see those stereograms, there’s another type you can try: cross-view stereograms.
It is an apparently double image, but with subtle differences between one and the other. Crossing the view, a third image appears in the middle… Which is the same as the previous ones, but in 3D!
To test these stereograms you must first cross your eyes. When a third image appears in the middle, that is, when the other two images are unified, make an effort to focus your vision on the new image.
Try to see the image of the girl above with this technique…The result will surprise you!
Why can’t everyone see them?
Some people, no matter how hard they try in a thousand different ways, can’t see the stereograms. Most just aren’t doing it right: but some truly never will.
This happens because to see 3d images, the eyes have to work as a coordinated team. But some people have vision problems that prevent this from happening.
The most common causes are: deviations or misalignments of one or both eyes (“crossed eyes” or strabismus), situations where one eye is dominant because the visual stimulation is either transmitted poorly, or directly not transmitted from one of the eyes . Astigmatism or cataracts can also play a role.
Have you managed to see the figures in 3D? What did you think?
Share them with your friends to see if they can see them!