[vtkusers] extracting a ROI in vtkImageData

[mloepp]

Hello vtk-users,

I'm new in developing in vtk and having some trouble to extract a region of
interest.

I've got a medical image (*.nrrd) which I've cropped to extract just one
axial layer.
Now I'd like to set a point inside the ROI and extract all voxels in this
layer which have a specific intensity value.

I can't find any vtk class in which I can set as an input a vtkImageData,
and extract my ROI by setting an intensity condition. The output should
also be a vtkImageDate.

Any ideas how I can do this?

Thanks in advance,
Martin