1. Introduction
Face detection is a very challenging issue; the main difficulty is that the face is a kind
of highly non-rigid target, such as appearance, facial expression, and color difference.
There might be some people face appendages such as glasses, beard, etc. The face poses
change evil, and there may be a shelter. Differences in nature of the image are to be
detected, such as waiting for the resolution of the image, the quality of video recording
equipment, etc.