Method for user function operation based on face recognition and mobile terminal supporting the same

A user interface system in a mobile terminal, comprising:

• a camera module to acquire an image of a target object in response to generation of data indicating an event during a video chat;
• and
• a control unit configured to control, in response to detecting a face in the acquired image:
• analyzing the facial image data to identify an emotional characteristic of the face by identifying a facial feature and comparing the identified feature with a predetermined feature associated with an emotion,
• determining similarity between the identified emotional characteristic of the face and a previously determined emotional characteristic of a face in a previously acquired image, and
• in response to the identified emotional characteristic being dissimilar to the previously determined emotional characteristic, generating an emotion indicative image based on the acquired image and transmitting the generated emotion indicative image to a counterpart terminal, and in response to the identified emotional characteristic being similar to the previously determined emotional characteristic, transmitting a message indicating similarity between the identified emotional characteristic and the previously determined emotional characteristic.