[vtkusers] How to display vtkImageDifference?

[Wolfram H Volpi]

Please help me with this question.
How to display output from a vtkImageDifference to a vtkTkRenderWidget?

This is what part of my tcl script looks like:

vtkTkRenderWidget .top.f1.f2.f1.f2.ren
    .top.f1.f2.f1.f2.ren config -width 256 -height 256 
    BindTkRenderWidget .top.f1.f2.f1.f2.ren

set renWin2 [.top.f1.f2.f1.f2.ren GetRenderWindow]
    vtkRenderer ren2
    $renWin2 AddRenderer ren2

vtkImageDifference imgDiff
    imgDiff2 SetImage [ReaderRefr GetOutput]
    imgDiff2 SetInput [ReaderTest GetOutput]

# How to display imgDiff in .top.f1.f2.f1.f2.ren?

Thank you for your help,
Wolfram Volpi.