+
+\subsection{File - Properties}
+The displayed properties include:
+
+\begin{itemize}\itemsep=0pt
+\item Number of detectors in the projections.
+\item Number of views.
+\item The parameters used when generating the projections from the phantom.
+\end{itemize}
+
+\subsection{Process - Convert Rectangular}
+The commands takes the projection data and creates an image file using
+the projection data.
+
+\subsection{Process - Convert Polar}\label{IDH_DLG_POLAR}\index{Polar conversion}
+This command creates an image file with the polar conversion of the projection data.
+The parameters to set are:
+
+\begin{twocollist}
+\twocolitem{\textbf{X Size}}{Number of columns in output image.}
+\twocolitem{\textbf{Y Ssize}}{Number of rows in output image.}
+\twocolitem{\textbf{Interpolation}}{Selects the interpolation method.
+Currently, the \texttt{bilinear} option provides the highest
+quality interpolation.}
+\end{twocollist}
+
+\subsection{Convert - Convert FFT Polar}
+The parameters for this option are the same as the \helprefn{Convert
+Polar Dialog}{convertpolardialog}. For this command, though, the
+projections are Fourier transformed prior to conversion to polar
+image.
+
+\subsection{Convert - Interpolate to Parallel}
+This command filters divergent projection data (equiangular or
+equilinear) and interpolates (or rebins) to estimate the projection
+data if the projections had been collected with parallel geometry.
+
+\subsection{Analyze - Plot Histogram}
+Plots a histogram of projection data attenuations.
+
+\subsection{Analyze - Plot T-Theta Sampling}
+Plots a 2-dimensional scattergram showing the \texttt{T} and
+\texttt{Theta} values for each data point in the projection data.
+This is especially instructive when scanning with divergent
+geometries and the scan ratio is close to \texttt{1}.
+
+\subsubsection{Theta Range}\label{IDH_DLG_THETA_RANGE}
+This dialog box allows the constraint of Theta values for the
+T-Theta Sampling scattergram.
+
+\subsection{Reconstruct - Filtered Backprojection}\label{IDH_DLG_RECONSTRUCTION}\index{Dialog!Reconstruction}
+This command displays a dialog to set the parameters for reconstructing an image from projections
+using the filtered backprojection technique. The parameters available are:
+
+\begin{twocollist}
+\twocolitem{\textbf{Filter}}{Selects the filter to apply to each
+projection. To properly reconstruct an image, this filter should
+consist of the the absolute value of distance from zero
+frequency optionally multiplied by a smoothing filter. The optimal
+filters to use are:
+\begin{itemize}\itemsep=0pt
+\item \texttt{abs\_bandlimit}
+\item \texttt{abs\_hamming}
+\item \texttt{abs\_hanning}
+\item \texttt{abs\_cosine}
+\end{itemize}
+} \twocolitem{\textbf{Hamming parameter}}{Sets the alpha level for
+Hamming window. This parameter adjusts the smoothing of the Hamming
+filter and can range from \texttt{0} to \texttt{1}.
+At a setting of \texttt{1}, the Hamming filter is the same as the bandlimit filter.
+At a setting of \texttt{0.54}, the Hamming filter is the same as the Hanning
+window.}
+\twocolitem{\textbf{Filter Method}}{Selects the filtering method.
+For large numbers of detectors, the FFT-based filters are preferred whereas for
+smaller numbers of detectors \texttt{convolution} can be
+faster. When \emph{Advanced Options} have been turned off, this menu only shows
+the two basic choices: \texttt{convolution} and \texttt{FFT}. However, when
+\emph{Advanced Options} have been turned on, additional selections are available as
+discussed in the next section.
+}
+\twocolitem{\textbf{Interpolation}}{Interpolation technique during backprojection.
+\texttt{cubic} has optimal quality when the
+data is smooth. Smooth data is obtained by taking many projections and/or
+using a smoothing filter. In the absence of smooth data, \texttt{linear} gives better results and
+is also many times faster than cubic interpolation.
+
+\begin{itemize}\itemsep=0pt
+\item \texttt{nearest} - No interpolation, selects nearest point.
+\item \texttt{linear} - Uses fast straight line interpolation.
+\item \texttt{cubic} - Uses cubic interpolating polynomial.
+\end{itemize}
+}
+\end{twocollist}
+
+\textbf{Advanced Options}
+
+These options are visible only if \emph{Advanced Options} has been
+selected in the \texttt{File - Preferences} dialog. These parameters
+default to optimal settings and don't need to be adjusted except
+by expert users.
+
+\begin{twocollist}
+\twocolitem{\textbf{Filter Method}}{Selects the filtering method.
+The general comments about this parameter given the previous section still apply.
+With \emph{Advanced Options} on, the full set of filter methods are available:
+\begin{itemize}\itemsep=0pt
+\item \texttt{convolution}
+\item \texttt{fourier} - Uses simple Fourier transform.
+\item \texttt{fourier-table} - Optimizes Fourier transform by precalculating trigometric functions.
+\item \texttt{fftw} - Uses complex-valued Fourier transform with the \emph{fftw} library.
+\item \texttt{rfftw} - Uses optimized real/half-complex Fourier transform.
+\end{itemize}
+}
+\twocolitem{\textbf{Backprojection}}{Selects the backprojection
+technique. A setting of \texttt{idiff} is optimal.
+\begin{itemize}\itemsep=0pt
+\item \texttt{trig} - Use trigometric functions at each image point.
+\item \texttt{table} - Use precalculated trigometric tables.
+\item \texttt{diff} - Use difference method to iterate within image.
+\item \texttt{idiff} - Use integer iteration techique.
+\end{itemize}
+}
+
+\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 \texttt{direct}
+\item \texttt{inverse-fourier}
+\end{itemize}
+}
+
+\twocolitem{\textbf{Zeropad}}{Zeropad factor when using
+frequency-based filtering. A setting of \texttt{1} is optimal whereas
+a setting of \texttt{0} disables zero padding. Settings greater than \texttt{1}
+perform larger amounts of zero padding but without any significant benefit.}
+
+\twocolitem{\textbf{ROI}}{These four settings control the
+\textit{region of interest} for the reconstruction. The default values
+match the dimensions of the entire phantom. By constraining the ROI to
+be a smaller square, the reconstruction will be magnified.}
+
+\end{twocollist}
+
+\subsection{Reconstruct - Filtered Backprojection (Rebin to Parallel)}\label{IDH_DLG_RECONSTRUCTION_REBIN}\index{Dialog!ReconstructionRebin}
+The command reconstructs the projection data via filtered backprojection
+as described above. As opposed to the above command, this command also
+rebins divergent projection data to parallel prior to reconstruction.
+This greatly speeds reconstruction of divergent geometry projections.