code: public void setImage (Mirage image)
      {
          if (_mirage != null) {
              _totalTileMemory -= _mirage.getEstimatedMemoryUsage();
          }
          _mirage = image;
          if (_mirage != null) {
              _totalTileMemory += _mirage.getEstimatedMemoryUsage();
          }
      }
docs: Configures this tile with its tile image.