A computer has been used to decipher the enigmatic smile of Leonardo da Vinci's Mona Lisa, concluding that she was mainly happy.
The painting was analysed by a University of Amsterdam computer using "emotion recognition" software.

It concluded that the subject was 83% happy, 9% disgusted, 6% fearful and 2% angry, journal New Scientist was told.

The computer rated features such as the curvature of the lips and crinkles around the eyes.

The program, developed with researchers at the University of Illinois, draws on a database of young female faces to derive an average "neutral" expression.

The software uses this average expression as the standard for comparisons.

The New Scientist says that software capable of recognising emotions just by looking at photographs could lead to PCs that adjust their response depending on the user's mood.