Abstract: Apparatus defines a dither mask (DM) and printmask (PM) 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 (e.g.

Abstract: One invention form is a method using all input data for one or preferably plural colorants, one time to control colorant deposition in forming a pixel array on a printing medium, and at least one other time to control deposition of more of the same colorants. At least one “applying” includes choosing data-array pixels to deposit added colorant. The two data-usage times can be associated directly with depositing colorant in respective printer passes; or may be done at (or near) rendition, sending output data to printmasking for pass allocation. Selection preferably includes setting maximum density on the medium—and choosing locations for that density, best by analyzing data to find locally dense areas, e. g. counting neighboring pixels. Selecting also includes defining locations to receive particular density, and creating additional density levels based on densities in the data array.