1. An image data processing method comprising: accessing image data of an image and comprising a plurality of pixels; defining a plurality of subsets of the pixels; defining an overlapping region comprising image data of pixels located adjacent to a boundary intermediate one and an other of the subsets; independently processing the image data of the one and the other of the subsets individually comprising comparing the image data for respective ones of the pixels with a plurality of thresholds corresponding to respective ones of the pixels; and modulating the thresholds of the pixels of the overlapping region using a common modulation pattern for both the processing of the one and the other subsets.