How to cartoon-ify an image programmatically?

Question

My app works with photos and videos of people, which I want to cartoonify. So I need an algorithm to do it manually (we use c++/Qt for our product, which has image manipulat

Answer 1

You might want to check out Freestyle, an open-source (Google Summer of Code, even) project to implement a non-photorealistic renderer for Blender. Here's an example of its output, in cartoon-mode:
_{(source: sourceforge.net)}