Decoupling Strokes and High-Level Attributes for Interactive Traditional Drawing

We present an interactive system, which allows the user to produce drawings in a variety of traditional styles. It takes as input an image and performs semi-automatic tonal modeling. Our system shifts tedious technical aspects to the computer side, while providing the user with freedom on the creative and aesthetic side. The user has low-level control over stroke placement, and high-level control over the tone, smudging and amount of detail. The drawing is rendered in real-time. The basic component is a thresholding model of strokes that can simulate a large class of styles (e.g. pencil, charcoal, engraving). It provides a controllable simulation of the variation of pencil pressure or stroke thickness traditionally used in tonal modeling. We introduce a novel fast equilibration approach for the resulting thresholding structure. The user can specify smudging and control the amount of detail over each part of the drawing.