Anaglyph

Anaglyph is a method of presenting stereoscopic 3D images or video by encoding the left-eye and right-eye views using different colors, typically red for the left eye and cyan for the right eye. When viewed through corresponding color-filter glasses, each eye sees only its intended image, creating the perception of depth through binocular disparity.

The technique relies on the separation of color channels and the human visual system’s tendency to fuse two offset views into a single 3D scene. Anaglyphs can be produced from stereo photographs, computer-generated imagery, or by processing existing images and video to assign one view to the red channel and the other to the cyan channel. Early experiments and developments in the 19th and early 20th centuries laid the groundwork for widespread use in printed media and cinema before polarization and active-shutter systems became dominant.

Standard red-cyan anaglyphs are common, but other color combinations such as red-green or blue-yellow exist. Color fidelity is typically degraded because the color channels are repurposed for depth encoding, making natural colors harder to reproduce accurately. Ghosting or cross-talk may occur if there is imperfect color separation, misalignment, or low-quality glasses.

In practice, anaglyphs are simple and hardware-compatible, requiring only a standard display and a pair of color-filter glasses. They remain useful for quick, low-cost 3D demos, educational materials, and archival content where more advanced stereoscopic systems are impractical. Modern usage often prioritizes neutral or grayscale images to minimize color distortion, or employs digital processing to reduce ghosting and improve depth cues.