Types

• Stereoscopic imaging relies on the use of a stereoscope to present a slightly different image to each eye. The stereo pair can be viewed with the naked eye, if the images are placed side by side. The stereo pair is then viewed using the same viewing technique used to see autostereograms.

• Freeviewing is viewing a side-by-side image without using a viewer.^[7]
   

  • The parallel view method uses two images not more than 65mm between corresponding image points; this is the average distance between the two eyes. The viewer looks through the image while keeping the vision parallel; this can be difficult with normal vision since eye focus and binocular convergence normally work together.

  • The cross-eyed view method uses the right and left images exchanged and views the images cross-eyed with the right eye viewing the left image and vice-versa. Prismatic, self masking glasses are now being used by cross-view advocates. These reduce the degree of convergence and allow large images to be displayed.

   

• Anaglyph images, also recognized as "red/green" or "magenta/cyan" images, combine two stereo images from slightly different viewpoints into a single image. These images may then be viewed with "anaglyph glasses", which use color filters to moderate the light reaching each eye to create the illusion of a three dimensional image.
• Random dot stereograms employ either two stereoscopic images or one anaglyph. The input image (or images) contain random dots with no discernible shapes. When the proper viewing device is used, a hidden 3D scene emerges from these random dots.
• Autostereograms produce an illusion of depth using only a single image. The image is usually generated by computer by repeating a narrow pattern from left to right. By decoupling eye convergence from focusing operations, a viewer is able to trick the brain into seeing a 3D scene.
• An autostereogram is a single-image stereogram (SIS), designed to create the visual illusion of a three-dimensional (3D) scene from a two-dimensional image in the human brain. In order to perceive 3D shapes in these autostereograms, the brain must overcome the normally automatic coordination between focusing and vergence.

  The simplest type of autostereogram consists of horizontally repeating patterns and is known as a wallpaper autostereogram. When viewed with proper vergence, the repeating patterns appear to float above or below the background.

   

• SIRDS (Single Image Random Dot Stereogram) is a form of autostereogram where each repeated pattern is altered slightly, creating a hidden image which is not discernible unless the right viewing technique is used.
• Wiggle-gram is an animated computer image which gives 3D percept without using glasses using only a single image. It usually contains a few frames.
  Advantages of the wiggle viewing method include:

  • No glasses or special hardware required
  • Most people can "get" the effect much quicker than cross-eyed and parallel viewing techniques
  • It is the only method of stereoscopic visualization for people with limited or no vision in one eye

  Disadvantages of the "wiggle" method:

  • Does not provide true binocular stereoscopic depth perception
  • Not suitable for print, limited to displays that can "wiggle" between the two images
  • Difficult to appreciate details in images that are constantly "wiggling"
  • Lack of 3D illusion to those who can detect the wiggling too easily.

  Most wiggle images use only two images, leading to an annoyingly jerky image. A smoother image, more akin to a motion picture image where the camera is moved back and forth, can be composed by using several intermediate images (perhaps with synthetic motion blur) and longer image residency at the end images to allow inspection of details. Another option is a shorter time between the frames of a wiggle image through the use of an animated .png.