[vtkusers] Getting pixel values

[TJ Wilkinson]

I am using vtkImager, vtkImageMapper, vtkActor2D to display 3D volumes
slice-wise.  I would like to probe the underlying pixel values.  Should I
use a Picker for this, or just use the interface somehow?  And once I have
the point in terms of the image extent, what method is appropriate to call
to find out the pixel value?  Do I need to GetScalarPointer and index to
the pixel in question?

Thank you.

Todd