1. A printer controller configured to perform a method of page expansion and printing of image data received from a computer, said method comprising the steps of: receiving a page description from the computer, the page having a bi-level black layer and a continuous tone (“contone”) layer, decompressing the respective layers in parallel; halftoning the contone layer data to bi-level data; compositing the bi-level black layer over the bi-level data to form an image; and printing the composite image with a pagewidth printhead.