@staticmethod
def crop_face(image, x1, y1, x2, y2, copy=True):
    """
        cropped 된 얼굴을 반환합니다.

        Overloaded function list.

        :param image: image
        :param x1,y1,x2,y2: face's coordinates, each points are left,top,right,bottom.
        :param copy: return copy data, default True


        :return: cropped face
        """
    if copy:
        return image[y1:y2, x1:x2, :].copy()
    else:
        return image[y1:y2, x1:x2, :]
