    //! Access to pixel value with Neumann boundary conditions \const.
    T atNXYZC(const int pos, const int x, const int y, const int z, const int c) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXYZC(): Empty instance.",
                                    cimglist_instance);

      return _atNXYZC(pos,x,y,z,c);
Unknown