a charge - coupled device imager has an output shift register having a number of bits equal to at least a multiple , where n is an integer greater than 1 , times the number of columns of pixels in the imager . appropriately spaced in the output shift register are n groups of n outputs each for non - destructive , simultaneous readout of n × n bits . the n × n bits are then available for pre - processing or display without the requirement for having previously stored each bit , digitally represented , in a computer memory .