Nonlinear resampling for edge preserving moiré suppression

Printing applications using classical halftoning need to resample the original image to a screen lattice. This resampling can cause undesirable moiré artifacts in the screened image. Some printing techniques, e.g., gravure printing, are highly susceptible to moiré, not only because of the low resolution screen lattices they employ but also because the degree of freedom in constructing halftone dots is limited by the physical constraints of the engraving mechanism. Current resampling methods compute new samples by simple interpolation techniques which cannot prevent sampling moiré very well. Therefore precautions against moiré have to be made in the pre-press phase which is not practical and sometimes not feasible. A novel technique is presented to adaptively resample an image on the screen lattice using a local estimate of the risk of aliasing. The purpose is to suppress moiré while maintaining the sharpness of the image. Experimental results demonstrate the feasibility of the proposed approach.