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

        Openning: Erode firstly, then Dilate.

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

        Returns:
            openning_raster: raster image after open.
        """
        input_raster = RasterUtilClass.read_raster(input_rasterfilename)
        openning_raster = input_raster
        for i in range(times):
            openning_raster = RasterUtilClass.raster_erosion(openning_raster)
        for i in range(times):
            openning_raster = RasterUtilClass.raster_dilation(openning_raster)
        return openning_raster
Do openning.

        Openning: Erode firstly, then Dilate.

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

        Returns:
            openning_raster: raster image after open.