Use Edge Detect to trace the edges in a clip based on colour. This data can then be used to create a range of artistic effects in various colour spaces.
To access the Edge Detect menu, use:
Timeline, then use ConnectFX (see Creating ConnectFX).
Tools, then select from the menu (See Accessing Tools).
The Modular Keyer, then select a node from the Node bin.
This node accepts a front and matte clip, and outputs a result and an outmatte.