1. A method of operating a multiple node image processing system to process data corresponding to an image, the method comprising the steps of: (a) generating an identifier for identifying a region of the image to which a block of said data relates; (b) storing said identifier; (c) repeating steps (a) and (b) for a plurality of blocks of said data; and (d) operating a combiner to assemble a final image for display, wherein the identifier is added to tag each block of data and to provide the combiner with instructions as to which blocks of data are to be used to assemble the final image.