    voi = vtkExtractVOI()
    voi.SetInputConnection(reader_volume.GetOutputPort())
    voi.SetVOI(0, 517, 0, 228, 0, 392)
    voi.SetSampleRate(1, 1, 1)
    voi.Update()  # Necessary for GetScalarRange().
    srange = voi.GetOutput().GetScalarRange()  # Needs Update() before!
--
    extractVOI = vtkExtractVOI()
    extractVOI.SetInputConnection(reader.GetOutputPort())
    extractVOI.SetVOI(0, 255, 0, 255, 45, 45)
    # scalarRange = extractVOI.GetOutput().GetScalarRange()
    scalarRange = [500, 1150]
    # print(scalarRange)
--
    extractVOI = vtkExtractVOI()
    extractVOI.SetInputConnection(reader.GetOutputPort())
    extractVOI.SetVOI(0, 255, 0, 255, 45, 45)

    iso = vtkContourFilter()
    iso.SetInputConnection(extractVOI.GetOutputPort())
--
        extract = vtkExtractVOI()
        extract.SetInputConnection(func.GetOutputPort())
        extract.SetVOI(0, dims[0] - 1,
                       0, dims[1] - 1,
                       sliceNum + sliceIncr, sliceNum + sliceIncr)
        append.AddInputConnection(extract.GetOutputPort())
--
        extract = vtkExtractVOI()
        extract.SetInputConnection(func.GetOutputPort())
        extract.SetVOI(0, dims[0] - 1,
                       0, dims[1] - 1,
                       sliceNum + sliceIncr, sliceNum + sliceIncr)
        ranges = [1.0, 6.0]
