    reader_volume = vtkMetaImageReader()
    reader_volume.SetFileName(ifn)
    reader_volume.Update()

    # Extract the region of interest.
    voi = vtkExtractVOI()
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)
    reader.Update()

    # Pad the volume so that we can change the point data into cell
    # data.
--
    reader = vtkMetaImageReader()
    histogram = vtkImageAccumulate()
    if use_flying_edges:
        try:
            using_marching_cubes = False
            discrete_cubes = vtkDiscreteFlyingEdges3D()
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)

    # An isosurface, or contour value of 500 is known to correspond to the
    # skin of the patient.
    if use_flying_edges:
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)

    # An isosurface, or contour value of 500 is known to correspond to the
    # skin of the patient.
    # The triangle stripper is used to create triangle strips from the
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)
    reader.Update()

    # An isosurface, or contour value of 500 is known to correspond to
    # the skin of the patient.
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)

    # The volume will be displayed by ray-cast alpha compositing.
    # A ray-cast mapper is needed to do the ray-casting.
    volume_mapper = vtkFixedPointVolumeRayCastMapper()
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)
    reader.Update()

    # An isosurface, or contour value of 500 is known to correspond to the
    # skin of the patient.
--
    reader = vtkMetaImageReader()
    reader.SetFileName(fileName)
    reader.Update()

    extractVOI = vtkExtractVOI()
    extractVOI.SetInputConnection(reader.GetOutputPort())
--
    reader = vtkMetaImageReader()
    reader.SetFileName(file_name)
    reader.Update()

    locator = vtkMergePoints()
    locator.SetDivisions(64, 64, 92)
--
    reader = vtkMetaImageReader()
    reader.SetFileName(fileName)
    reader.Update()

    extractVOI = vtkExtractVOI()
    extractVOI.SetInputConnection(reader.GetOutputPort())
--
    reader = vtkMetaImageReader()
    reader.SetFileName(fileName)
    reader.Update()

    cast = vtkImageCast()
    cast.SetInputConnection(reader.GetOutputPort())
--
    reader = vtkMetaImageReader()
    reader.SetFileName(str(file_name))
    reader.Update()

    select_tissue = vtkImageThreshold()
    select_tissue.ThresholdBetween(tissue, tissue)
--
    reader = vtkMetaImageReader()
    reader.SetFileName(str(file_name))
    reader.Update()

    select_tissue = vtkImageThreshold()
    select_tissue.ThresholdBetween(tissue, tissue)
--
    reader = vtkMetaImageReader()
    reader.SetFileName(str(fn))
    reader.SetDataSpacing(data_spacing)
    reader.SetDataOrigin(data_origin)
    reader.SetDataExtent(voi)
    reader.Update()
--
    grey_reader = vtkMetaImageReader()
    grey_reader.SetFileName(str(fn_1))
    grey_reader.Update()

    grey_padder = vtkImageConstantPad()
    grey_padder.SetInputConnection(grey_reader.GetOutputPort())
--
    segment_reader = vtkMetaImageReader()
    segment_reader.SetFileName(str(fn_2))
    segment_reader.Update()

    segment_padder = vtkImageConstantPad()
    segment_padder.SetInputConnection(segment_reader.GetOutputPort())
