Upon receiving the image data 98, the memory 78 stores the image data 98 according to the data clock 116, for example, loading bits of image data 98 bit by bit on each rising edge of the data clock 116. The memory 78 outputs the image data 98 to be added to binary data stored in the accumulator 150. While the accumulator 150 is shown as being an 8-bit accumulator, it should be understood that any suitable accumulator or register may be used to temporarily store data. The adder 152 may perform binary addition of the image data 98 and binary data of the accumulator 150 in response to an emission clock 154, for example, a rising edge of the emission clock 154. The sum from the adder 152 is transmitted for storage in the accumulator 150 for use with next image data 98 while a carry bit is used to open and/or close the switch 104.