Computer-Generated Watercolor by Cassidy J. Curtis, Sean E. Anderson, Joshua E. Seims, Kurt W. Fleischer, David H. Salesin

Presents a series of techniques for modeling the behavior of watercolor paint on paper in rather thorough detail. Simulates edge-darkening, backruns, glazing, dry-brush, and several other characteristics of watercolor. The technique can be used for painting ala Photoshop, although the paper notes that interactive painting is impossible with the current technology (133 MHz SGI R4600 chip!), creating watercolor from a photograph with manually specified mattes, or from a 3D render. Temporal coherence is not solved (the technique is prone to ’shower-door’ artifacts), but the single-frame results are quite nice. It’s a considerably more advanced model than the one used by Painter or Photoshop.