In the first method, the two images needed to create the effect are combined into one image. Each image can be altered by a color filter or a polarized filter. With the color filter the viewer will wear 3-D glasses with two different colored lenses. The glasses then block out one of the two combined images so each eye sees a different angle of the same shot, producing a 3-D effect. Orginially this method, called Anaglyph, required 3-D to be created without a color picture, but modern advances have allowed 3-D the use of color with this method--although color quality still suffers. Polarization uses the same princliple but rather than altering the color of an image it alters the waves of light the viewer sees. The glasses the viewer wears have differently polarized lenses which only show one image to each eye. Picture quality is better with this method and it is what is used in most 3-D movie theaters.