text: Then,Your home PC can't hanlde the complex algotithms used to decode Mona Lisa's smile. But we can wrtie down some simple instruction that"encode"different emotion. In fact,these are the instructions for a face that looks happy. It;s all about those muscular action units. Humans could tell a friend is feeling simply by he look on her or hise face. Of course,most of us would have trouble actually describing each facial trait that convy happy,worried.