Anaglyph 3D

Anaglyph 3D is the stereoscopic 3D effect achieved by encoding each eye's image using filters of different, usually chromatically opposite, colors, typically red and cyan. Anaglyph 3D images contain two differently filtered colored images, one intended for each eye. When viewed through color-coded anaglyph glasses, each image is visible only to the eye it is intended for, revealing an integrated stereoscopic image. The visual cortex of the brain fuses those images into the perception of a three-dimensional scene or composition.

Anaglyph images have seen a recent resurgence due to the prevalence of images and video on the Web, on Blu-ray, 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 three primary colors. Although most common color filters used today are red and cyan, with red being used for the left channel and vice versa, the filters used in the past used red and blue for convenience and cost. There is a significant improvement in the reproduction of full color images using the cyan filter, especially for accurate skin tones.

Video games, theatrical films, and DVDs can be shown using 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 mission STEREO, which uses two orbital vehicles to obtain three-dimensional images of the sun. Other applications include geological illustrations by the United States Geological Survey, and various online museum objects. A recent^[timeframe?] application is stereo imaging of the heart using 3D ultrasound with plastic red/cyan glasses.

Anaglyph images are much easier to view than either parallel (diverging) or crossed-view stereograms. However, these side-by-side types offer bright and accurate color rendering, which is not easily achieved with anaglyphs. Also, extended use of the anaglyph glasses can cause discomfort, and the afterimage caused by the colors of the glasses may temporarily affect the viewer's visual perception of real-life objects. In the mid-2000s, cross-view prismatic glasses with adjustable masking have appeared, offering a wider image on modern HD video and computer monitors.

The oldest known description of anaglyph images was written in August 1853 by W. Rollmann in Stargard and described his "Farbenstereoscope" (color stereoscope). He had the best results when viewing a yellow/blue drawing with red/blue glasses. Rollmann found that with a red/blue drawing the red lines were not as distinct as yellow lines when viewed through the blue glass.

In 1858, in France, Joseph D'Almeida [fr] delivered a report to l'Académie des sciences describing how to project three-dimensional magic lantern slide shows using red and green filters to an audience wearing red and green goggles. Subsequently, he was credited with being responsible for the first realisation of 3D images using anaglyphs.

Louis Ducos du Hauron produced the first printed anaglyphs in 1891. This process consisted of printing the two negatives which form a stereoscopic photograph onto the same paper, one in blue (or green), one in red. The viewer would then use colored glasses with red for the left eye and blue or green for the right eye. The left eye would see the blue image which would appear black, while it would not see the red; similarly the right eye would see the red image, which would also register as black. Thus, a three-dimensional image would result.

William Friese-Green created the first three-dimensional anaglyphic motion pictures in 1889, which were publicly exhibited in 1893. 3-D films enjoyed something of a boom in the 1920s. As late as 1954, films such as Creature from the Black Lagoon remained very successful. Originally shot and exhibited using the Polaroid system, Creature from the Black Lagoon was successfully reissued at a later date in an anaglyph format so it could be shown in cinemas without the need for special equipment. Today, the excellent quality of computer displays and user-friendly stereo-editing programs offers new possibilities for experimenting with anaglyph stereo.