[Paraview] Making a certain color in an image transparent

[David Doria]

I want to make one color of an image (a traditional 2D image) totally
transparent and leave the rest in tact. I have some mask files (white
and green pixels) and I want only the green pixels to be displayed in
ParaView. The white pixels should be transparent so I can see the
original image in that region (when I also have it opened in
ParaView).

I can do it in VTK using vtkImageMapToColors with a vtkLookupTable
(http://www.vtk.org/Wiki/VTK/Examples/Cxx/Images/Transparency) but is
it possible in ParaView?

Thanks,

David