Stereoscopic film projection

Three dimensional optical effects may be obtained in both still and motion picture film based on separating out light signals for the left and right eyes. This may be done by two lens cameras in filming, or by viewers wearing 'magic' spectacles, which usually uses the well-known blue-green and red separability for the two eye-pieces. American 3-D films are sometimes used by industry for product promotion and by pornographers. The invention of holography promises a high technical achievement in projecting fully-dimensional imagery.