public documents.sextractor_doc

\chapter{Overview of the software}

\label{techover}

%---------------------------------- Fig. layout -------------------------------

   \begin{figure}[htbp]

      \centerline{\includegraphics[width=15cm]{ps/sexlayout.ps}}

      \caption{

              Layout of the main {\sc SExtractor} procedures. \emph{Dashed arrows} represent optional

              inputs.

\gam{I omitted the dashes from ``Flag map'', ``Weight map'' (using InkScape).}

              }

      \label{fig:layout}

   \end{figure}

The complete analysis of an \index{image} image is done in two passes through the data. During the first pass, a

\index{mode} model of the sky background is built, and several global statistics are estimated. During the

second pass, the \index{image} image is background-subtracted, filtered and \index{threshold} thresholded ``on-the-fly''.

Detections are then deblended, pruned (``CLEANed''), photometered, classified and finally written

to the output catalogue. The following sections describe each of these

operations in more detail.\footnote{In the text, uppercase keywords in typewriter font refer to parameters from the

\index{configuration file} configuration file or from the \index{parameter file} parameter file}