code: def add_depth_channel(img_tensor, pad_mode):
      '''
      img_tensor: N, C, H, W
      '''
      img_tensor[:, 1] = get_depth_tensor(pad_mode)
      img_tensor[:, 2] = img_tensor[:, 0] * get_depth_tensor(pad_modef add_depth_channel(img_tensor, pad_mode):
      '''
      img_tensor: N, C, H, W
      '''
      img_tensor[:, 1] = get_depth_tensor(pad_mode)
      img_tensor[:, 2] = img_tensor[:, 0] * get_depth_tensor(pad_mode)
docs: img_tensor: N, C, H, W