What are stereograms

Stereograms (magic eyes) are images  that gives the illusion, when we see it ( with a certain technic), to have in front of us a 3D  image.

Its functioning depends by the human visual system.

In fact eyes perceive the same objects and forms in different manner and by different perspectives (the distance between eyes is about 6cm.).
Is the brain that synthesize the two images creating one 3D image.

Stereograms are created with two different images, each one per eye and slightly different between them, and if you look at it with a certain method, they lead on brain to perceive one 3D image.

esempio di uno stereogramma di inzio 900

Example of stereograms (begin 1900).

The ones I propose and the most common on the web are called “autostereograms” and their feature is that they are composed of just one image covered by a texture coloured or in B/W.

The texture can be a random dots image or a fantasy of colors.

The term “stereoscopic” was created by the Belgian jesuit François d’ Aguillon in 1613, that use this term in his essay ” Opticorum libri sex: philosophis juxta ac matematicis utiles” (Six books of optic: useful as for philosophers as for mathematicians).

The functioning of stereograms was discovered by the philosopher and english inventor sir. Charles Wheatstone in 1838, but before him Euclid, the greek philosopher, Leonardo and other were fascinated about the theme and studied it.

Sir. Wheatstone, knowing the functioning of visual system in the humans, created, for the first time, a stereoscope, an instrument based on mirrors and prisms,
that helped each eye to focus on the right image to see, giving the possibility to get the stereographic 3D image.

Looking to the images with the stereoscope the viewer had the impression to see the 3D one.

It made simple the view of the 3D image, possible also without any helping instrument and called “simple stereoscopic view”.

Example of simple stereoscopic view. Look the two dots until you
will see a third dot between them. Look the image and it will be in 3D.

After that is sir. David Brewster that in 1849 improve the Wheatstone’s stereoscope, making it smaller and compact, giving a boost to the diffusion of stereograms during the rest of 1800.

Stereoscopio di sir Brewster

Stereoscope of sir. David Brewster.

At the beginning of the XX century the stereograms lose their appeal due to the born of cinema.

All the studies on stereograms gave the possibility to adopt this system and derivative ones in the cinema industry (3D movies) and in comics.

For more info, here the link to the Wikipedia page upon stereograms.

You can be interested to read: how to see stereograms

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