How it worksStereoscopic images (3D-pictures) are made up from 2 separate images which are superimposed in such a way that your left eye only sees the 'left' image, and your right eye only the 'right' one. Because of the limited resolution of computer monitors the best way of doing this is with anaglyphs: One picture is colour-coded in red, the other in blue. Then the two are superimposed. Anaglyphs have no real colour. You will perceive them more or less in black and white.
To view the images you need to wear red-blue glasses (red-green ones will work fine too). A good way to test if it works for you is the anaglyphic contour map of Stromboli below. When viewed using the glasses the island must seem to grow out of the screen towards you. The red window of the glasses must be on the left!