Producing Anagliph Images

Producing anaglyph images

        In historical methods using camera filters, on film, two images from the perspective of the left and right eyes were projected or printed together as a single image, one side through a red filter and the other side through a contrasting color such as blue or green or mixed cyan. As outlined below, one may now, typically, use an image processing computer program to simulate the effect of using color filters, using as a source image a pair of either color or monochrome images. Since the 1970s Stephen Gibson offers his patented "Deep Vision" system using cyan instead of green filters. These colors cover the entire visible spectrum, providing more natural color. "Deep Vision"-spectacles have the red filter over the right (!) eye and the cyan over the left. (To bypass Gibson's patent some companies produce red/cyan-glasses with the colors on the wrong sides.)

• Popular professional programs such as Adobe Photoshop provide the basic digital tools for processing of anaglyphs. They do not provide instruction for anaglyph in their basic documentation. Various websites offer free instruction related to 3D for Photoshop. Simple, low cost programs, dedicated to anaglyph creation, are also available. In recent simple practice, the left eye image is filtered to remove blue & green. The right eye image is filtered to remove red. The two images are usually positioned in the compositing phase in close overlay registration (of the main subject).
  
  
• In Photoshop, for example, a function called "screen" in the "layers" (F7) option allows the two filtered layers to be combined transparently on top of each other, although the compositing can also be done by pasting the selected channels. The filtration itself can easily be done in the "curves" function, which allows removal of any red, green, or blue layer with a simple slider. Experienced Photoshop users can sometime process a good cross-view 3D pair into a color anaglyph in 2 to 5 minutes if little fine-tuning is required. Various steps can also be used to maximize the quality of the result. These may include size matching of the frames to within a few pixels, rotation (if needed), gamma leveling, and digital sharpening of the softer red image. It should be noted that both the red layer in the image and the red filter in the glasses contain no visible blue or green color information, but masked colors do exist that the eyes cannot see through a red filter that can interact with the colors contained in the cyan image after compositing and blending.