Do closing.

        Closing: Dilate firstly, then Erode.

        Args:
            input_rasterfilename: input original raster image filename.
            times: Erode and Dilate times.

        Returns:
            closing_raster: raster image after close.

def closing(input_rasterfilename, times):
        """Do closing.

        Closing: Dilate firstly, then Erode.

        Args:
            input_rasterfilename: input original raster image filename.
            times: Erode and Dilate times.

        Returns:
            closing_raster: raster image after close.
        """
        input_raster = RasterUtilClass.read_raster(input_rasterfilename)
        closing_raster = input_raster
        for i in range(times):
            closing_raster = RasterUtilClass.raster_dilation(closing_raster)
        for i in range(times):
            closing_raster = RasterUtilClass.raster_erosion(closing_raster)
        return closing_raster