\section{Advance Data Analysis}
\label{sec:analysis}

Besides basic interferometric imaging, \imager{} offers a number
of advanced tools that can be used to extract more information from
the available data than just by visual inspection of the deconvolved
images.

These tools are particularly usefull for weak signal detection.
Some of them are generic (e.g. the Matched Filtering), others 
specific of some astrophysical situations (e.g. the KEPLER tool)

\subsection{Matched Filtering}

Weak signal detection is always an issue in most astrophysical cases
(e.g. high redshift galaxies, faint lines in proto-planetary disks,
to cite some).

For spectral lines, \imager{} offers the \com{UV\_DETECT} command,
that uses an image model as an optimal filter to enhance weak line
detection.  This is a generic tool, that can use an observed data
cube (from a strong line, presumably) as the image model, or the
result of a simulation.

\subsection{Line Stacking}

Another aspect is spectral line stacking, when several lines are
assumed to follow the same spatial distribution. This can be
done using command \comm{UV\_MERGE}{/MODE STACK}. The stacked UV table result
can be imaged and analyzed as usual. Like \com{UV\_DETECT},
\com{UV\_MERGE} does not make any assumption on the source shape.

\subsection{Rotationally symmetric (thin) structures: Keplerian disks}

The \com{KEPLER} command re-aligns in velocity the spectra as a function
of radius (distance from the rotation center), by correcting from
the projection effect and radial velocity law. This allows to
stack spectra coming from the same radius, and thus to derive
radial profiles.

The result is a Position-Velocity image, and can be displayed conveniently
with the \comm{SHOW}{KEPLER} command.

The \com{KEPLER} command currently assumes the velocity law is Keplerian. 
Generalization to other (nearly arbitrary) laws will be performed later: 
this could be used for spectral lines in galaxies.

\subsection{Image Handling and Comparison}

Commands \com{MAP\_*} (\com{MAP\_COMBINE}, \com{MAP\_COMPRESS}, \com{MAP\_INTEGRATE}
\com{MAP\_REPROJECT}, \com{MAP\_RESAMPLE}, com{MAP\_SMOOTH} and \com{MAP\_CONTINUUM}
allow basic operations on Data Cubes.

Command \com{COMBINE} allows Data cube combinations, while command \comm{VIEW}{/OVERLAY}
allows comparing two data cubes.


