[vtkusers] Swapping image attributes

[John Biddiscombe]

> Is there a quick/simple way to retain a vtkImageData's
> topology and geometry but change its scalar data?  The desired
> result is to set a vtkUnsignedCharArray as the attributes to the
> image topology/geometry.

Look at PointData and see vtkDataArray. You can assign any type of array as
the point scalars.

Also See vtkFieldData->SetActiveScalars

JB