Stereo Images

There are several different types of three dimensional viewing and printing technologies available. Anaglyphs which present the left and right eye images as red or blue monochromatic images are among the simplest technique, but do not allow the use of full color images. Shutter Goggles that switch the visibility of left and right eyes as in the IMAX Stereo Theaters and Virtual Reality headsets allow for each eye to view a different image rendered by the computer. These methods require special viewer software and hardware to differentiate the left- and right-eye views. Our binocular vision enables us to view 3D objects because each eye sees a slightly different image of the scene from a slightly different viewpoint. In the brain, these two images are combined into a single stereoscopic perception, having the appearance of depth and volume.

Lenticular Images utilize a lenticular plastic sheet that has vertical ridges that form narrow cylindrical lenses. These lenses display a slightly different view to each eye depending on the angle between the eye and the lenticular sheet. The resulting lenticular images are autostereoscopic, meaning that they require no special viewers to display 3D imagery. A significant limitation of lenticular displays is that they display images with an apparent resolution that is governed by the width of the cylindrical lenses. However, the three-dimensional lenticular printouts have all the visual cues of an actual volume of space, including object positioning (foreground and background), parallax and shading, and 'look-around'. The hologram-like effect is quite remarkable, and the image can have a tremendous impact on the viewer. 3D COM, Inc. provides a commercial service printing stereo image sequences as lenticular printouts. Their URL is https://3dhardcopy.com/.

An alternative stereo inkjet printing technology that creates a high resolution, full color stereoscopic hard copy is called StereoJet (Scarpetti 1998 & 1996). In the StereoJet image the left and right views are printed onto opposite surfaces of a multi-layer sheet, using inks with polarizing properties. The polarizing axes of the two image-receiving layers are oriented at 90º to one another. By wearing polarized glasses viewers perceive the composite stereoscopic image in full depth. Each eye sees only the assigned image, and the brain processes the information to provide full binocular stereoscopic perception. Lenticular 3D prints do not have the resolution or clarity produced by this technology, however StereoJet prints require special glasses. StereoJet printing is quite expensive at about $300 per sq. ft., but the quality is very high. For additional technical information or a source for StereoJet printing, see https://www.rowland.org/stereo/ and https://www.slidefactory.com/SJmain.html.