Structure-preserving stippling by priority-based error diffusion.

This paper presents a new fast, automatic method for structure-aware stippling. The core idea is to concentrate on structure preservation by using a priority-based scheme that treats extremal stipples first and preferentially assigns positive error to lighter stipples and negative error to darker stipples, emphasizing contrast. We also use a nonlinear spatial function to shrink or exaggerate errors and thus implicitly provide global adjustment of density. Our adjustment respects contrast and hence allows us to preserve structure even with very low stipple budgets. We also explore a variety of stylization effects, including screening and scratchboard, all within the unifying framework of stippling.