Minimizing stochastic moiré in frequency-modulated halftones by means of green-noise masks

In color halftoning, moiré is the low-frequency spatial artifact generated by the interference of superimposed primary color dot screens that adds an unwanted artificial texture to the printed image. When these overlapping dot screens are irregular, as in the case of stochastic dot screens, this interference pattern follows a random spatial distribution resulting in "stochastic" moiré. This stochastic moiré is at its most visible when the overlapping dither patterns have the same relative spacing between dots. We study the occurrence of stochastic moiré in green-noise halftones where dither patterns are composed of clusters of varying sizes and where the visibility of stochastic moiré can be reduced by varying the coarseness of dither patterns between the component cyan, magenta, yellow, and black colors.