thumb|300px|A random dot autostereogram encoding a 3D scene of a [[shark, which can be seen with proper viewing technique (10px) ]]

It is estimated that some 1 percent to 5 percent of the population is affected by amblyopia.

3D perception

Depth perception results from many monocular and binocular visual clues. For objects relatively close to the eyes, binocular vision plays an important role in depth perception. Binocular vision allows the brain to create a single Cyclopean image and to attach a depth level to each point in it.

As with a photographic camera, it is easier to make the eye focus on an object when there is intense ambient light. With intense lighting, the eye can constrict the pupil, yet allow enough light to reach the retina. The more the eye resembles a pinhole camera, the less it depends on focusing through the lens. In other words, the degree of decoupling between focusing and convergence needed to visualize an autostereogram is reduced. This places less strain on the brain. Therefore, it may be easier for first-time autostereogram viewers to "see" their first 3D images if they attempt this feat with bright lighting.

Vergence<!--"vergence" is a real word spelled correctly--> control is important in being able to see 3D images. Thus it may help to concentrate on converging/diverging the two eyes to shift images that reach the two eyes, instead of trying to see a clear, focused image. Although the lens adjusts reflexively in order to produce clear, focused images, voluntary control over this process is possible. The viewer alternates instead between converging and diverging the two eyes, in the process seeing "double images" typically seen when one is drunk or otherwise intoxicated. Eventually the brain will successfully match a pair of patterns reported by the two eyes and lock onto this particular degree of convergence. The brain will also adjust eye lenses to get a clear image of the matched pair. Once this is done, the images around the matched patterns quickly become clear as the brain matches additional patterns using roughly the same degree of convergence.

thumb|400px|A type of wallpaper autostereogram featuring 3D objects instead of flat patterns ([[Image:Stereogram guide parallel.png|10px)]]

thumb|400px|The bottom part of this autostereogram is free of 3D images. It is easier to trick the brain into matching pairs of patterns in this area. ([[Image:Stereogram guide parallel.png|10px)]]

When one moves one's attention from one depth plane to another (for instance, from the top row of the chessboard to the bottom row), the two eyes need to adjust their convergence to match the new repeating interval of patterns. If the level of change in convergence is too high during this shift, sometimes the brain can lose the hard-earned decoupling between focusing and convergence. For a first-time viewer, therefore, it may be easier to see the autostereogram, if the two eyes rehearse the convergence exercise on an autostereogram where the depth of patterns across a particular row remains constant.

In a random dot autostereogram, the 3D image is usually shown in the middle of the autostereogram against a background depth plane (see the shark autostereogram). It may help to establish proper convergence first by staring at either the top or the bottom of the autostereogram, where patterns are usually repeated at a constant interval. Once the brain locks onto the background depth plane, it has a reference convergence degree from which it can then match patterns at different depth levels in the middle of the image.

The majority of autostereograms, including those in this article, are designed for divergent (wall-eyed) viewing. One way to help the brain concentrate on divergence instead of focusing is to hold the picture in front of the face, with the nose touching the picture. With the picture so close to their eyes, most people cannot focus on the picture. The brain may give up trying to move eye muscles in order to get a clear picture. If one slowly pulls back the picture away from the face, while refraining from focusing or rotating eyes, at some point the brain will lock onto a pair of patterns when the distance between them matches the current convergence degree of the two eyeballs. Dr. Christopher Tyler, inventor of the autostereogram, consistently refers to single image stereograms as autostereograms to distinguish them from other forms of stereograms. Programs for their creation include Mathematica.

  • Random dot autostereogram/hidden image stereogram

:Is also known as single image random dot stereogram (SIRDS). This term also refers to autostereograms where the hidden 3D image is created using a random pattern of dots within one image,

  • Wallpaper autostereogram/object array stereogram/texture offset stereogram

:Wallpaper autostereogram is a single 2D image where recognizable patterns are repeated at various intervals to raise or lower each pattern's perceived 3D location in relation to the display surface. Despite the repetition, these are a type of single image autostereogram.

  • Single image random text stereogram (SIRTS)

:A single image random text ASCII stereogram is an alternative to SIRDS using random ASCII text instead of dots to produce a 3D form of ASCII art.

  • Map textured stereogram

:In a map textured stereogram, "a fitted texture is mapped onto the depth image and repeated a number of times" resulting in a pattern where the resulting 3D image is often partially or fully visible before viewing.