Method and apparatus for pre-compensating an asymmetrical picture in a projection system for displaying a picture

摘要

An apparatus and method for correcting keystone aberration (trapezoidal distortion) of images projected on to screen (20) by a projection system (10), e.g. a liquid crystal (LCD) projector, when the projection screen (20) is not perpendicular to the optical axis (30) of the projection lens (11). The apparatus includes means (100) for inputting angular values indicating the inclination of the lens optical axis with respect to the screen plane, means (500) for storing digital signals representing the image to be projected and means (600) for converting the stored digital signals such that the image displayed on the liquid crystal display has a trapezoidal distortion compensating for the distortion caused by the inclination of the screen with respect to the projection lens.