Computer scientists at the University of Amsterdam have use an "emotion recognition" software to analyse Leonardo da Vinci's famous Mona Lisa ("La Joconde"). In case you don't know, the smile is seen differently by people...
The computer computer finds the subject 83% happy, 9% disgusted, 6% fearful and 2% angry...
For the detailed story check out BBC NEWS - Mona Lisa 'happy', computer finds