Techniques are described for determining optimum halftone masks for electrophotographic laser printers. Earlier techniques were based primarily on up-shifting the noise power of the halftone pattern in order to minimize visual granularity. This strategy worked well with low addressable printers up to the mid 1990s. However, current addressability of EP printers is so high that too much up-shifting introduces printer instabilities that can introduce different kinds of granularity and/or mottle. Thus, the optimum halftone mask for image quality should have noise power concentrated within at frequency band between the edge of human vision and the edge of printer stability. The authors have developed search techniques for examining permutations of halftone masks of size HxW. The techniques are based on a strategy called a genetic algorithm (GA).