In a cathode ray tube, plural electron beams are directed towards a faceplate biased at screen potential and are magnetically scanned by a non-self-converging deflection yoke across the faceplate to impinge upon phosphors thereon to produce light depicting an image. The plural electron beams are substantially converged near two opposing edges of the faceplate. A processor changes the raster of the image from a first raster corresponding to position of the image to a second raster corresponding to the position of the plural electron beams on the faceplate. One or more electrodes between the tube neck and the faceplate are biased above and/or below screen potential to deflect electrons landing near the periphery of the faceplate.