A technique which combines the advantages of blue noise and clustering obtains more pleasant "blueish" effects in the rendering of the grey levels for which the original multicell mask generates unwanted periodic representations. Such original multicell clustered dither array patterns which are undesirable are replaced by less periodic ones while preserving all benefits of the classical methods, and in particular, leaving the nicest patterns unchanged. An automated process redistributes the locations of the threshold values corresponding to undesirable grey levels to obtain more pleasant "blueish" effects in the rendering of the grey levels.