> It can be easy to forget, but try templating the filter over the adaptor type > instead of the image type. I.e., > > typedef > itk::BinomialBlurImageFilter<itk::NthElementImageAdaptor<itk::Image<itk::Covaria > ntVector<float, 3u>, 2u>, float> FilterType > > Regards, > Matt Ah, I get it now, thanks. David