finetune

gt_img = gt_img / 255.
        normal_img = normal_img / 255.
        mean_gray_out = cv2.cvtColor(normal_img.astype(np.float32), cv2.COLOR_BGR2GRAY).mean()
        mean_gray_gt = cv2.cvtColor(gt_img.astype(np.float32), cv2.COLOR_BGR2GRAY).mean()
        normal_img_adjust = np.clip(normal_img * (mean_gray_gt / mean_gray_out), 0, 1)

        normal_img = (normal_img_adjust * 255).astype(np.uint8)
        gt_img = (gt_img * 255).astype(np.uint8)