Here’s a stereogram, a picture which otherwise doesn’t make any sense.
However if you look at it in a particular way, you can see a beautiful 3D picture with a mountain range in the background, Sun rising and a Pair of birds (Flamingoes) in front.
The way to see it is that you need to balance the Right Eye’s vision and Left Eye’s vision equally on the picture to be able to see it.
Hold the picture in front of your eyes 1 foot away and instead of looking at the picture, look through the picture keeping your focus not on the picture but behind to some object in the far away distance behind.
Soon the picture will emerge and you will be able to see it in complete 3D.
Another way to see it is that with both hands, hold the picture initially close to your nose/ eyes with your focus in the distance and not to the picture. So the picture will obviously appear hazy/ blurred to the eyes. Very slowly keep moving the picture further away from the nose while keeping your focus behind and not on the picture. At a certain point, you will notice something different appearing on the picture and a 3D image will be seen.