public int Threshold {get; set;}

{
  //Export the map view associated with a map frame to BMP.
  string filePath = @"Path and file name for the output export file";
  //Create BMP format with appropriate settings
  //EMF, EPS, GIF, JPEG, PDF, PNG, SVG, TGA, and TFF formats are also available for export
  BMPFormat BMP = new BMPFormat()
  {
    Resolution = 300,
    Height = 500,
    Width = 800,
    HasWorldFile = true,
    OutputFileName = filePath
  };

  //Export on the worker thread
  await QueuedTask.Run(() =>
  {
    MapView mv_bmp = mapFrame.GetMapView(layoutView);
    if (mv_bmp != null)
    {
      //Check to see if the path is valid and export
      if (BMP.ValidateOutputFilePath())
      {
        mv_bmp.Export(BMP);  //Export to BMP
      }
    }
  });
}