A Novel Line Hatching Style through Conformal Mapping

Pen-and-ink line hatching is a non-photorealistic rendering (NPR) image style typically characterized by monochrome, locally near-parallel lines. Our motivation was to generate line hatching images inspired by the Grendel image by Emil Antonucci. Antonucci's images are composed of many cells containing relatively short near-parallel lines. We develop an automatic NPR system that converts a photo into an output image portraying a novel line hatching style. One key characteristic of our approach is its use of conformal mapping to reshape segmented regions into a standardized shape. After drawing the lines on the standardized shape, we then transfer the lines back to the segment region. The transformation automatically distorts the lines to follow the segment region contours. Our process generates line hatching images that have short near-parallel lines, lines that change direction to represent feature boundaries, line density and line width variations to represent tone intensity, edge lines, and line perturbations.