In stereoscopic reproduction methods for three-dimensional representations, the two images, which are offset in perspective, must be visible separately to each eye. Depending on the stereoscopic method, reproduction techniques are used that work with color filters, polarization filters
or with consecutively reproduced individual images. One of the older techniques is that using color filter glasses, also known as anaglyph glasses. In this technique, the two images for the right and left eye are colored in two colors
. The color filter in front of one eye only allows the image parts of the color filter to pass, the same applies to the color filter in front of the other eye.
Since the two images are offset in perspective, the observer perceives two offset images, which the brain interprets to form a three-dimensional image with depth effect.cyan were used as color filters. Later, these filters were replaced by red-green filters and other color combinations that produced better results.