+\twocolitem{\textbf{-\,-zeropad}}{Zeropad factor. A setting of
+\texttt{1} is optimal.}
+
+\twocolitem{\textbf{-\,-filter-generation}}{Selects the filter
+generation. With convolution, \texttt{direct} is the proper method
+to select. With any of the frequency methods,
+\texttt{inverse-fourier} is the best method.
+\begin{itemize}\itemsep=0pt
+\item direct
+\item inverse-fourier
+\end{itemize}