{TAIL ~ The pattern} of illuminated pixels changes smoothly with time to produce {HEAD ~ the required uniform high quality grey level} 
{ TAIL ~ The pattern } of illuminated pixels changes smoothly with time to produce { HEAD ~ the required uniform high quality grey level }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD