Since 2000, computer searches are leading to develop systems capable of recognising and interpreting human emotions. Clément Lambelet gets interested in process of facial automatic recognition and reflects upon its generalisation regarding to its development in every social media (Facebook, Instagram, Snapchat). For the book Happiness is the only true emotion, he worked on a panel of portraits given by the Pain Express Set from Stirling University in Scotland, he selected one emotion per person, reframed images and saved only the face. The artist manipulated each photograph and worked on its materiality to get more expressive images.These portraits become a vector of emotion. Each picture is then submitted to the Microsoft Cognitive Emotion API challenging the accuracy of these systems. The Emotion API only recognises Happiness with certitude.