Hairy brushes in computer-generated images

Paint brushes are modeled as a collection of bristles which evolve over the course of the stroke, leaving a realistic image of a sumi (Japanese watercolor) brush stroke. The major representational units are (1) Brush: a compound object composed of bristles, (2) Stroke: a trajectory of position and pressure, (3) Dip: a description of the initial condition of a class of brushes, and (4) Paper: a mapping onto the display device. A modular system allows experimentation with various models of ink flow and color change. By selecting from a library of brushes, dips, and papers, the stroke can then take on a wide variety of expressive textures.