3D Glasses feed different images to the eyes. On the screen, two images are displayed. The glasses make one image enter one eye, and the other to the other eye. This is done by two methods. The first is polarization. Here two synchronized projectors project two respective views on the screen. Each view has a different polarization. The polarizaed glasses permit only one of the images enter each eye. The second method is the use of RG or red-green glasses or RB or red-blue glasses. These see two images displayed on the screen — one red and the other blue (or green ). The glasses permit one image enter each eye. This creates a sense of depth.