apparatus defines a dither mask and printmask with corresponding dimensions . in one invention form the dm dimension is not an integral factor or multiple of the pm dimension . the two dimensions may be lengths or widths ; preferably the apparatus manages both ; the corresponding dimensions differ by at least three pixels , and by a multiple of two pixels — more preferably eight or a multiple of eight . preferably one dimension is an integral multiple of 256 pixels differing by eight pixels from the other . another invention form has a scanning printhead making multiple passes across a print medium to form swaths of marks , a mechanism to define an offset smaller than at least one of the two dimensions , and a unit to index one mask by that offset between forming of successive swaths . this is valuable if dm and pm are established by preprogrammed circuits or algorithms and one dimension is fixed at an integral multiple or factor of the other , with the system being practically incapable of small changes in the dimensions . another invention form is a print method that establishes and operates a rendition stage using a dm — and a pm stage using a pm .