The present invention relates to a set of image processing method and systems to be used in printers with asymmetrical-resolution printing mode. The asymmetrical-resolution is defined as having an aspect ratio of n=X:Y. The system first picks up a symmetrical-resolution halftone table and then, by making use of an algorithm such as an interpolation such as a B-spline method, expand the symmetrical-resolution halftone table by n times along the width direction to obtain an asymmetrical-resolution halftone table, in accordance with which the system will subsequently do the necessary pre-print processing of halftoning in order to print out the corresponding image(s).