1. A computing device comprising: a camera; and an image co-processor to (i) detect one or more features of an object in an image captured by the camera, (ii) assign a virtual point charge to each of the one or more detected features to simulate an electrostatic charge distribution, (iii) determine a virtual electric potential field that results from the simulated electrostatic charge distribution, and (iv) select a portion of the object in the captured image that is bounded by an equipotential line in the virtual electric potential field.