A multipass printing apparatus is characterized by a computer-implemented controller that controls printing operation so that, on any given pass, the number of selected print locations onto which printing ink is deposited by each of N nozzles varies from nozzle to nozzle. The variation is governed in accordance with a weighted smoothing spline function, particularly a polynomial B-spline function of the order "j", where j is a value equal to one less than the number of passes.