\section{Pre-amble}

%\textbf{This document is under construction; it is partly based on the older documentation of \mapping{}.}

\imager\ is an interferometric imaging package, tailored for usage
  simplicity and efficiency for multi-spectral data sets.

\textbf{\imager\  is *** NOT *** \mapping }

\imager{} was created because the initial infrastructure for imaging
in the \mapping{} program was not adapted to the implementation 
of imaging methods that became possible and/or were required for
\NOEMA{} (and useable for \ALMA{}), such as self-calibration,
wide band imaging, or routine processing of Mosaics and Short spacings.
 
The \imager{} design takes great care of efficiency, by using parallel 
programming and minimizing Input/Output on files. This lead to a 
concept with a single \com{READ} of data, a few (in general only 2) 
simple processing commands with built-in intelligent parameter guesses, 
a visual user control, and a single \com{WRITE} of the results once the 
user is satisfied of it.

We took the opportunity to revise and streamline the user interface,
providing access to all tools through simple commands. A special
effort was put on the visualization tools, which provide enhanced
speed and capabilities, yet preserving a very high level of compatibility
with those previously offered in \mapping{}.

\imager{} was derived from  \mapping{} by S.\,Guilloteau. T.\,Jacq and 
E.\,di\,Folco made numerous suggestions about the user interface, 
and helped testing and documenting the program. 
