Abstract: This paper describes the various artistic effects of watercolor and shows how they can be simulated automatically. Our watercolor model is based on an ordered set of translucent glazes, which are created independently using a shallow-water fluid simulation. We use a Kubelka-Munk compositing model for simulating the optical effect of the superimposed glazes. We demonstrate how computer-generated watercolor can be used in three different applications: as part of an interactive watercolor paint system, as a method for automatic image "watercolorization," and as a mechanism for non-photorealistic rendering of three-dimensional scenes.