In a rear projection television, cathode ray tubes are mounted inside an enclosure so that each cathode ray tube projects output images onto a rear projection screen using a corresponding electron beam. Calibration images are generated for each cathode ray tube. A camera, also mounted inside the enclosure, acquires an input image of each calibration image. A distortion in each input image is measured, and the output images of the cathode ray tubes are corrected by adjusting the signals controlling the corresponding electron beams according to the distortion.