mask_renderer.py Why is the face data made with masks not real at all?

import os, sys, datetime
import numpy as np
import os.path as osp
import cv2
import insightface
from insightface.app import MaskRenderer
from insightface.data import get_image as ins_get_image

if __name__ == "__main__":
#make sure that you have download correct insightface model pack.
#make sure that BFM.mat and BFM_UV.mat have been generated
tool = MaskRenderer()
tool.prepare(ctx_id=0, det_size=(128,128))
image = ins_get_image('Tom_Hanks_54745')
mask_image = "mask_black"
params = tool.build_params(image)
mask_out = tool.render_mask(image, mask_image, params)

cv2.imwrite('output_mask.jpg', mask_out)

@nttstar