User2130758966 posted
This technique's technical name is "Cel-shading":
I searched high and low for any reference to it but couldnt find an implementation in .net
I think with the latest WPF and Silverlight implementations you can use hardware shaders. It might be easier to find a cel shader for use with that...
Also I guess there must be another technical name for doing this to 2d images because true Cel-shading (as the wiki article describes) relies on rendering 3d information about the scene such as the depth buffer.