• Binocular vision permits us to perceive objects as having depth or three dimensions. Each eye receives an image from a slightly different horizontal angle (normally 7 degrees for an object held at arms length). The visual cortex interprets these two images as a three dimensional object. Stereopair images are two dimensional images of an object taken from a left and right perspective. If the right eye only sees the image taken from the right perspective and the left eye only sees the image taken from the left perspective, the brain can be fooled into thinking it sees a three dimensional image. The can be done in several ways. Glasses with colored lenses can be used to exclude artificially colored superimposed stereo images from the left and right eye (i.e. red lens excludes cyan and cyan lens excludes red). This is the anaglyph method. The images of corrosion casts below are anaglyphs and when viewed with red-cyan glasses (red on the left) the images appear in three dimensions. Each image is linked to a larger version