How to Crop vtkImageData using vtkBoxWidget that can living inside or outside?

I cropped the vtkImageData using vtkBoxWidget (inside), but now I want to crop it outside. How can i do?

auto clippingPlanes = vtkSmartPointer::New();
double *bounds = clippingPlanes->GetPoints()->GetBounds();

auto volumeMapper = vtkVolumeMapper::SafeDownCast(clipVolumeData->GetMapper());
volumeMapper->CroppingOn();//Enable Crobing
volumeMapper->SetCroppingRegionPlanes(bounds[0], bounds[1], bounds[2], bounds[3], bounds[4], bounds[5]);

But how should i crop that outside.