Creating 3-D Red/Blue Anaglyphs from Photographs
The ability to create 3-D images is currently a hot marketing tool as new technology has sparked interest in three dimensional media. One of the oldest and least expensive methods to create and reproduce a 3-D image is the anaglyph. Anaglyphs are a method of encoding a three-dimensional image in a single picture by superimposing a pair of pictures. The anaglyph consists of a left and right image encoded to create the perception of depth in the image. Anaglyphs are not difficult to create, however creating good anaglyphs is a craft. A poorly made anaglyph can make the viewer feel uncomfortable. The most important and difficult part of the anaglyph is creating the original photographs or images. The originals should have depth in the image; otherwise the anaglyph will not exhibit much 3-D effect. Objects in the foreground of the original photographs will create the appearance of depth or accentuate the 3-D effect.
The original images should be bright and ideally not have much red. With the red/cyan-blue anaglyph glasses, the right eye sees blue and green, the left eye sees gray. What about red? Red is absent, some light leakage through the glasses’ filters may produce limited red, and professional anaglyph designers go to great lengths to tweak the color channels to produce some resemblance of red, but this will never approach commercial quality color. Black and white or duotone anaglyphs can be used to compensate for problems with color reproduction shortcomings, especially reds in memory colors.
Original photo-fluorescent pink geranium
Simulation of loss of red in anaglyph viewed thorough red-cyan glasses, gray balance is better in the 3-D anaglyph.
A stereo camera with two lenses that captures both left and right images simultaneously in the exact same plane is the preferred method to create the left and right images for the anaglyph. A single lenses camera can be used if mounted on a tripod with a slide that enables the same image to be photographed several inches apart. With a single lens/image camera, the subject can not move between images. A limitation to the single lenses/image camera is anything that moves including people, pets, and clouds which will produce an unusable stereo image. The last method is free hand, where the photographer tries to hold the camera exactly the same and only shifts a couple of inches to the right for the second image. This method is unreliable and may require many attempts to produce a useable left and right image.