“…In many practical face recognition systems, for example, law enforcement, entrance monitoring, intelligent video surveillance, criminal identification, the gallery set is typically designed using only one single sample per person (SSPP) [7] because of the limited storage and privacy policy. What makes the situation even worse is that the probe samples are usually captured with video surveillance cameras under unconstrained conditions [8,9]. Therefore, SSPP face recognition in this unconstrained environment is very challenging task due to, first, the strong intraclass variations such as illumination [10][11][12], pose [12,13], facial expression [14][15][16] and occlusion [17,18], and second, the lack of gallery samples.…”