US Patent 7261388 Error reduction by print masks

In a method of printing a plurality of pages during a print job, a page-wide-array printing device having redundant dot-forming elements is used. Print masks distribute dot-forming-element activity between the redundant dot-forming elements in a manner taking into account known malfunctions of dot-forming elements to hide such malfunctions, or reduce a visible effect of such malfunctions in the pages printed. The method includes generating a plurality of print masks which are different, as they distribute the dot-forming-element activity in different ways, but are equivalent, since they are based on the same knowledge of dot-forming-element malfunctions; dividing the print job into page-sets of at least one page; and printing the different page-sets of the print job using different equivalent print masks, thereby distributing the dot-forming-element activity in different ways from page-set to page-set.