Anaglyph: Oldest of the technologies. Two projectors throwing overlaping images— in cyan and red shades—on the screen and fool the brain into seeing depth. Polarising: The screen produces two polarised images—vertical and horizontal— for each eye. When filtered by polarising glasses, a 3D image is received. Active Shutter: Active shutters in the glasses are in sync with the screen. Alternate and very fast turn on/off generates different images for the two eyes. Glasses are battery-powered. Lenticular: Future lies here. Alternately interlaced images meant exclusively for the left and right eyes pass through half- cylindrical lenses and the brain constitues a 3D image. No glasses needed here.