parser.add_argument('--conf_threshold',type=float,default=0.9,help='Filter out faces of confidence < conf_threshold.')
parser.add_argument('--nms_threshold',type=float,default=0.3,help='Suppress bounding boxes of iou >= nms_threshold.')
parser.add_argument('--top_k',type=int,default=5000,help='Keep top_k bounding boxes before NMS.')
parser.add_argument('--keep_top_k',type=int,default=750,help='Keep keep_top_k bounding boxes after NMS.')
parser.add_argument('--save','-s',type=str,default=False,help='Set true to save results. This flag is invalid when using camera.')
parser.add_argument('--vis','-v',type=str2bool,default=True,help='Set true to open a window for result visualization. This flag is invalid when using camera.')