1. An apparatus comprising: an image input unit configured to input an image; a face detection unit configured to detect a face image of a person from the image input by said image input unit; a first calculation unit configured to calculate a first expression evaluation value corresponding to a first facial expression for the detected face based on the face image detected by said face detection unit; a second calculation unit configured to calculate a second expression evaluation value corresponding to a second facial expression for the detected face based on the face image detected by said face detection unit, wherein the second facial expression is different from the first facial expression; an updating unit configured to update, based on the first expression value, a relationship between the second expression value and a threshold value for determining a facial expression of a person; and a judgment unit configured to judge whether the detected face shows the second facial expression or not based on the relationship between the second expression value and the threshold value which is updated by said updating unit.