import tensorflow as tf

        tmp_bboxes = _calc_bounding_boxes()
        bboxes = np.vstack((bboxes, tmp_bboxes)) # <class 'tuple'>: (5265, 5)    
    
      # non maximum suppression
      # refind_idx = util.nms(bboxes, nms_thresh)
      refind_idx = tf.image.non_max_suppression(tf.convert_to_tensor(bboxes[:, :4], dtype=tf.float32),
                                                   tf.convert_to_tensor(bboxes[:, 4], dtype=tf.float32),
                                                   max_output_size=bboxes.shape[0], iou_threshold=nms_thresh)
      refind_idx = sess.run(refind_idx)
      refined_bboxes = bboxes[refind_idx]
      overlay_bounding_boxes(raw_img, refined_bboxes, lw)
      if display:
