1. An image processing method applicable to a frame sequence comprising multiple frames, each frame comprising multiple groups of image elements, said method comprising the steps of: determining a representation of a global motion of image element property values from at least a reference portion of a reference frame ( 20 ) to at least a portion of a frame; identifying, for a first group of at least one image element in said frame, a first reference group of at least one image element in said reference frame based on said global motion representation; and calculating a first classification parameter as being representative of a difference in image element property values of said first group and said first reference group; identifying a second reference group of at least one image element in said reference frame based on a displacement vector associated with said first group; identifying a second group of at least one image element in said frame based on said global motion representation and said second reference group; and calculating a second classification parameter representative of a difference in image element property values of said second reference group and said second group, said first classification parameter and said second classification parameters are indicative of whether said first group belongs to a foreground or a background of said frame