Computer main memory is used for storing relatively densely sampled green and detail information concerning a television display and for storing relatively sparsely sampled red information and blue information concerning the same television display. The relatively densely sampled green and detail information is read out in substantially real-time from computer main memory during line trace intervals in the television display. The relatively sparsely sampled red information and blue information are read out of computer main memory in advanced and compressed time during selected line retrace intervals in the television display.