There are a number of ways to view stereo images on your computer. This page will look at some of the basic approaches in terms of what additional equipment (if any) is required and what are the advantages and disadvantages of each approach. By the way, if you are equipped to view some of these examples, you may be discouraged by the quality of some of the samples. The problem is the graphics compression used by many ISP's. Don't worry, as we shall see, there is a way around the problem that doesn't involve slowing your browser by disabling graphics compression!
Side-by-Side Free-Viewing
In this approach, the stereo pairs are displayed side-by-side for so-called free viewing. To see the stereo effect, you need to focus beyond the image, causing your eyes to cross in a way that lets the images merge into a single stereo view. The advantage of this technique is that no equipment is required, but the disadvantages are serious:
Anaglyph Images
The least-expensive way to comfortably view stereo images on your computer is to use a set of viewing glasses with red (left eye) and blue, green, or cyan (right eye) lenses. Stereo pictures designed to be viewed with such glasses are known as anaglyph images. Glasses are available from several sources on the Internet. One good place to look is Berezin Stereo Photography Products. Several different models are available, depending on your needs and budget. Red/Cyan glasses work with all common anaglyph options and typically, in my opinion, deliver superior results. Every serious stereo enthusiast should have a pair of anaglyph glasses within reach of the computer console! Unlike the various free-viewing options, anaglyph images are not limited in terms of image size and format. They also print reasonably well (if you have a color printer). These features, coupled with the low cost of the viewing glasses, make anaglyph images quite popular. In most cases, you will see anaglyph images of two general types:
Color analgyphs retain most of the colors of the original scene. Although the colored glasses will distort the color to some extent, you get a stereo view with some of the original image color intact. The quality of the stereo effect will depend somewhat on the colors in the original picture. Some examples can look quite good, while others will show color ghosting or other effects that can detract from your appreciation of the picture. Here is where the problem of Internet graphics compression starts to appear. Color anaglyphs are tricky and most compression will distort the colors just enough to start to give problems with "ghosting".
Gray-scale anaglyphs are made using black and white versions of the original pictures, so any colors in the original image cannot detract from the stereo effect. If an image doesn't look quite right in color anaglyph form, it may be fine as a gray-scale anaglyph. Unfortunately, because there are fewer colors, graphics compression is a more serious problem with the gray-scale versions of most images.
Liquid-Crystal Shutter Glasses
Anaglyphs provide a convenient and inexpensive option for viewing stereo images, but they do fall short of a full-color 3D experience! If you get really interested in computer stereo images, the ultimate solution for stereo viewing is liquid-crystal "shutter" (LCS/LCD) glasses. The glasses are made of liquid-crystal material whose transparency is changed by an external controller. When the computer displays an LCS-compatible image, it actually displays material for the left and right views of the scene in sequence. When data for the right view are being displayed, the left lens is opaque - the left eye doesn't see the "right eye image". The right eye goes black when the left-hand image data are being displayed. As a result, each eye sees only its particular "view" and your brain does the usual magic of merging the left and right images into a stereo view. The advantages are that the LCS images are in full, natural color and they can be in any aspect ratio or resolution. With LCS glasses, your computer screen looks like a window opening onto a completely realistic, full-color 3-D view of whatever is being displayed.
LCD viewing systems can be quite expensive, but Vrex Incorporated offers several affordable LCS system that do a fine job. The glasses pictured here are the VRex VR Visualizers which sell for about $30! They come complete with a cable and hand controller and are simple to install. You simply insert the connector (which is supplied) between the computer and the monitor cable. The hand-controller lets you switch "on the fly" to accommodate a variety of image formats. The glasses are active only when a 3-D image is being displayed and have no effect on normal computer operation, including other web-surfing.
The package, which will end up costing about $35 with shipping and handling, includes the glasses (A), a hand-controller unit (B), a pass-through video connector (C), and a complete CD-ROM that you won't need. Installation of the glasses couldn't be easier:
To use then with stereoscope, simply select the shutter view option (left first). The glasses are very light and comfortable to wear and the fit over eyeglasses without any problem. The instruction manual describes the use of the hand-controller.
With respect to my galleries, you should select the following stereo display options:
This is highly affordable virtual reality and is the next-best-thing to actually being there when a photo was taken! These glasses also work with a variety of stereo video formats that can provide full color, full-motion stereo viewing via your computer. Believe me, it is a small investment that can take you Internet viewing experience to the next level.
*NOTE: These glasses only work with CRT monitors. If you
are using a flat-panel LCD or plasma monitor, LCD glasses will not work.
Lens/Mirror Screen Viewers
Systems made up of lenses and mirrors, such as this ScreenScope Viewer make it
possible to view virtually any side-by-side (parallel) stereoview. Mirror spacing is
typically adjustable to accommodate different image sizes. The result is bright,
flicker-free viewing limited only by the resolution of the display and the image in
question.
Ralph E. Taggart (taggart@msu.edu)