# File easy_vtk.rb, line 1214
  def save_file( filename, options={} )
    type = 'png'
    options.each{ |key, val|
      case key
      when 'type'
        type = val
      else
        raise "option (#{key}) is invalid"
      end
    }
    w2i = Vtk::WindowToImageFilter.new
    w2i.SetInput( @renWin )
    case type
    when 'png'
      writer = Vtk::PNGWriter.new
    when 'jpeg'
      writer = Vtk::JPEGWriter.new
    when 'bmp'
      writer = Vtk::BMPWriter.new
    when 'tiff'
      writer = Vtk::TIFFWriter.new
    when 'ps'
      writer = Vtk::PostScriptWriter.new
    when 'pnm'
      writer = Vtk::PNMWriter.new
    end
    writer.SetInput( w2i.GetOutput )
    writer.SetFileName( filename )
    @renWin.Render
    w2i.Update
    writer.Write
    return nil
  end