Getting to the hidden picture behind is a tricky process. The best way to view it is to stare at the middle spot of the picture keeping your eyes very near to the picture. Slowly you will start getting a slight focus of the picture and then it gets easier. While keeping the concentration towards the picture also keep your eyes relaxed. Staring and concentrating both along with relax mind would make you take a look at the hidden picture behind.
Also, sometimes some people are unable to view the hidden pictures within the 3D picture. There can be many causes such as eye dominance or convergence or conditions like exotropia and exophoria. As the basic idea behind a 3D picture is dependence of a person's capability to merge multiple objects into a single one. So, one should adjust the distance of his eyes from the picture according to his vision capability, as there is not any universal distance that would work for everyone. Not to forget that, the capability to see behind the image lies in the people with analytical and artistic minds.
A 3D picture has the ability to trick a person's brain in doing what it keeps on doing in the real world. Anyone at all, with a camera, computer equipment and Photoshop software and a pair of 3D glasses can learn to make this stereogram. It is a fun technique to play with photos of all kinds. The initial 3D photos which were viewed in white and black were known as anaglyphs. They were simple and it was easy to pick out the image. The colored anaglyphs got a bit trickier. These 3D images were not required any equipments to snap out the illusion behind.
The 3D technique can be used to make pictures that fascinate young children a lot. This is also good for kids to learn to use there analytical side of the mind. This creates a power to think beyond in them. Alongside it is also an interesting way to make children learn many different things. 3D pictures can also be used for children of younger age to learn and pick different things. As almost by the age of 3 all kids establish their basic binocular vision. These pictures are not harmful to view for young eyes; rather making them view these pictures can help us detect a problem earlier i.e. if there is any.