OK, I know that an image is created by the reflection of light back to your eyes. And I know the color for a part of an image is given by the frequency or wavelength of light being reflected back to your eye. But what gives it the 3D (non flat look) i.e what gives an image it's depth. If it is the distance at which light reaches your eye then how does your body keep track of what light source is farther or closer away? Somebody told me it has to do with polarization. But I don't really understand how this can differentiate it. Thanks for any help.