Let's explore 3D Stereo...

What is 3D Stereo?
3D Stereo refers to viewing an image stereoscopically (perceived dimension).

What is Stereoscopic Viewing (stereopsis)?
Stereopsis is the perception of depth derived from two slightly different camera angles of an image (left eye, right eye) projected onto the retinas of the left and right eye. The differences in the two retinal images are called horizontal disparity, retinal disparity, and/or binocular disparity. The differences arise from the unique left and right eye view associated with their position in the head. The mind processes the two images into one volumetric or 3D image.

What is Stereoscopy (stereoscopic or 3D imaging)?
Stereoscopy refers to a technique for creating or enhancing the illusion of depth in an image by presenting two offset images separately to the left and right eye of the viewer. Both of these 2-D offset images are then combined in the brain to give the perception of 3-D depth.

What is Auto-Stereoscopic (Multi-view) Viewing?
Auto-Stereoscopy is any method of displaying stereoscopic images without the use of special headgear or glasses on the part of the viewer. Because headgear is not required, it is also called "glasses-free 3D" or "glasses-less 3D". The two main technologies currently being used are parallax barrier and lenticular.

Parallax Barrier technology consists of a layer of material positioned in front of a display with a series of precision slits, allowing each eye to see a different set of pixels, so creating a sense of depth through parallax in an effect similar to what lenticular printing produces for printed products. A disadvantage of the technology is that the viewer must be positioned in a well-defined spot to experience the 3D effect and due to the covering portion of the barrier, these displays tend to be not as bright as the original display. Another disadvantage is that the effective horizontal pixel count viewable for each eye is reduced by one half; however, there is research attempting to improve these limitations.

Lenticular Lens technology
Lenticular Lens technology consists of a layer of material positioned in front of a display with an array of optical elements called "lenticules" (long cylindrical lens) that create a convex perspective of multiple images. The multiple images are slices of different camera angles of the same image called views. The views are arranged under the lens so that each eye is projected a different view (Left Eye / Right Eye). The brain then processes these views to a single coherent 3D image.

What is Parallax?


Parallax is a difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. Nearby objects have a larger parallax than more distant objects when observed from different positions.

What is Anaglyphs?
Anaglyph images are used to provide a stereoscopic 3D effect, when viewed with glasses where the two lenses are different (usually chromatically opposite) colors, such as red and cyan. Images are made up of two color layers, superimposed, but offset with respect to each other to produce a depth effect. Usually the main subject is in the center, while the foreground and background are shifted laterally in opposite directions. The picture contains two differently filtered colored images, one for each eye. When viewed through the "color coded" "anaglyph glasses", they reveal an integrated stereoscopic image. The visual cortex of the brain fuses this into perception of a three dimensional scene or composition.

Anaglyph images have seen a recent resurgence due to the presentation of images and video on the Internet, Blu-ray HD discs, CDs, and even in print. Low cost paper frames or plastic-framed glasses hold accurate color filters that typically, after 2002, make use of all 3 primary colors. The current norm is red and cyan, with red being used for the left channel. The cheaper filter material used in the monochromatic past dictated red and blue for convenience and cost. There is a material improvement of full color images, with the cyan filter, especially for accurate skin tones.

Video games, theatrical films, and DVDs can be shown in the anaglyph 3D process. Practical images, for science or design, where depth perception is useful, include the presentation of full scale and microscopic stereographic images. Examples from NASA include Mars Rover imaging, and the solar investigation, called STEREO, which uses two orbital vehicles to obtain the 3D images of the sun. Other applications include geological illustrations by the USGS, and various online museum objects. A recent application is for stereo imaging of the heart using 3D ultra-sound with plastic red/cyan glasses.

Anaglyph images are much easier to view than either parallel (diverging) or crossed-view pairs stereograms. However, these side-by-side types offer bright and accurate color rendering, not easily achieved with anaglyphs. Recently, cross-view prismatic glasses with adjustable masking have appeared, that offer a wider image on the new HD video and computer monitors.

A 3D television (3D-TV) is a television set that employs techniques of 3D presentation, such as stereoscopic capture, multi-view capture, or 2D plus depth, and a 3D display a special viewing device to project a television program into a realistic three-dimensional field.