code: @Override
  	public double getValue(GriddedTile griddedTile, TileRow tileRow, int x,
  			int y) {
  		BufferedImage image = null;
  		try {
  			image = tileRow.getTileDataImage();
  		} catch (IOException e) {
  			throw new GeoPackageException(
  					"Failed to get the Tile Row Data Image", e);
  		}
  		double value = getValue(griddedTile, image, x, y);
  		return value;
  	}
docs: {@inheritDoc}