One of the many charms of the stereoscopic arts is that the display of the imagery can take so many different forms. The galleries on this blog will show a variety of 3d image formats: Anaglyph, Stereoview, Stereo Pair (x-eyed), Stereo Slide, 3D video.
An “anaglyph” is an image where color is used to multiplex the left-eye and right-eye view into a single image space. A pair of anaglyph glasses is used by the audience to decode and fuse the stereoscopic image. This means that the color filtering allows the left eye to see only the image intended for the left eye, and the same for the right eye. Anaglyphs have several advantages and one distinct disadvantage. One advantage is that they can be shown on any color screen, or printed on most any type of surface, at any size. Being able to print very large anaglyphs makes them attractive for installations (e.g. in a bricks and mortar fine art gallery). Another advantage is that they are very easily duplicated in print, making anaglyphs attractive for printed mass-media, comic books, etc. The distinct disadvantage is in the viewing mode, which requires conflicting color filters over each eye. Before the brain can get used to this viewing mode, the audience experiences visual confusion. Even the experienced lover of anaglyphs, who will have no trouble seeing the image clearly, knows that to obtain a true color 3d view is nearly impossible.
“Stereo pair” is the oldest display format for stereoscopic imagery. The very first 3d images ever made were stereo pairs, predating even photography (they were drawings by Wheatstone). Stereo pairs have the advantage of affording a full color view, but the disadvantage (usually) of requiring a stereoscope to view them (“stereo pair” or side-by-side “SBS” is also a format ingested by 3DTVs, then output on the screen in either polarized or frame alternate multiplexed form, for viewing with the appropriate 3d glasses).
The most popular photographic 3d image format is a “stereoview,” a stereo pair of images printed on a seven inch wide card, for viewing in a stereoscope. In a stereoview the left-eye image is to the left, and the right-eye image to the right (an LR stereo pair), each one about three inches wide. Stereoviews were widely popular from the late nineteenth century up until the radio era in the early twentieth century. The stereoscope magnifies the images, providing an immersive visual experience. Because of their one time popularity, vintage stereoviews attract collectors of old photographs in general. I make my modern images into stereoviews for sale to such collectors.
For display on non-3D capable screens – i.e. most screens that people use online – stereo pairs are also suitable for “free viewing” without a stereoscope. Free-viewing is a technique that can be learned, allowing you to view stereo pairs with the naked eyes, so that they appear fused into a cohesive 3d image. There are two ways to show stereo pairs for free-viewing: parallel-eyed, and cross-eyed. Many people prefer the so-called cross-eyed stereo pair format, where the left-eye image is put to the right, and the right-eye image is put to the left (an RL stereo pair). These can then be free-viewed at any size, even quite large. By contrast, the more traditional LR stereo pairs can be free-viewed at only a fairly small size, where each image is little more than about 2 inches wide on-screen. Larger sizes would require a stereoscope.
Stereo slides are both a viewing format and an image acquisition format. In other words, you can shoot slide film in stereo – either in a dedicated stereo camera or in two separate cameras – and with very minimal post-processing view the resulting slides in a slide stereoscope. Stereo slides can provide some of the finest 3d image viewing experiences possible, as there are no generational losses from image acquisition to the viewing medium. The slide film starts as the image sensor, then after image processing becomes the image display surface. As such, the level of detail and resolution, the brilliance of color, the dynamic range, and the subtlety of the tonality that are reproduced are unmatched by any other photographic medium. While digital media now have the potential to surpass slide film in some of these qualities, It will be a long time before they can do so with the low cost, compactness, and versatility of slide film.
Certainly 3D video provides an important feature that cannot be claimed by the traditional stereoscopic media: motion / animation. But 3D video is also encumbered by the same format choices and limitations. I produce an occasional 3D video to be published on YouTube, but this distribution platform comes with its own snafus and difficulties, both in distribution and formatting. Another problem is that the installed base of 3DTVs is not very large and shrinking (though 3DTV has resulted in a larger installed base of stereoscopic viewing equipment than has ever been seen before, in the history of the art). Making up for this is the rise of the VR headset or goggle – e.g. Oculus Rift – perhaps yet another display format, rising in popularity.