Diffusion curve

Diffusion curves are vector graphic primitives for creating smooth-shaded images. Each diffusion curve partitions the 2D graphics space through which it is drawn, defining different colors on either side. When rendered, these colors then spread into the regions on either side of the curve in a way analogous to diffusion. The colors may also be defined to vary smoothly along the curve and the sharpness of the color transition from one side of the curve to the other may also be specified.