combination with the color subcarrier component derived from b r y and a b y to form the composite ntsc signal in order that the eight parallel outputs referred to above may be obtained simultaneously it is convenient to divide the total memory into eight blocks into which the data samples of the input video signal are written sequentially in a sequence of four memory blocks on one line and the other four on the next line repeating in alternate line sequence this arranges the samples so that each memory block holds the values given by one of the expressions 1 through 8 above all eight memory blocks area always read in parallel the reading addresses of all blocks being subjected to the same processing for picture manipulation other methods of obtaining eight parallel outputs from a memory such as serial reading followed by buffering to provide parallel outputs are of course possible but practically less convenient at the high reading speeds required for data representing video signals it is not necessary that the eight memory blocks into which the input data is written be the same as those from which the final output is derived it is possible to write into eight memory blocks in sequence as described above and subsequently to transfer the data in these first eight memory blocks in parallel into a.