    source1 = vtkImageCanvasSource2D()
    source1.SetScalarTypeToUnsignedChar()
    source1.SetNumberOfScalarComponents(3)
    source1.SetExtent(0, 100, 0, 100, 0, 0)
    source1.SetDrawColor(colors.GetColor4ub('SteelBlue'))
    source1.FillBox(0, 100, 0, 100)
--
        canvas_source = vtkImageCanvasSource2D()
        canvas_source.SetExtent(0, 100, 0, 100, 0, 0)
        canvas_source.SetScalarTypeToUnsignedChar()
        canvas_source.SetNumberOfScalarComponents(3)
        canvas_source.SetDrawColor(colors.GetColor4ub('warm_grey'))
        canvas_source.FillBox(0, 100, 0, 100)
