Introduction

The LN DRS consists of a data reduction framework and a set of modules which provide algorithms for all processing steps (calibration, preprocessing, target preprocessing, psf preprocessing and reconstruction). A complete data reduction and image reconstruction setup is specified by:

A set of input files which are the result of an observation run (raw data, sky images, flatfield and bad pixel map).
A set of intermediate files (calibrated data, preprocessed data, target and psf).
The reconstructed object (reconstruction and the convolved reconstruction).
A selected algorithm for each processing step and the specific parameters.

This information is stored in a parameter file, which can be created and modified by hand or with the graphical user interface (started with the command ldrs_gui). If a parameter file is already created, all processing steps can be carried out without a GUI by executing the pipeline with the command ldrs_pipeline.

The LN DRS framework uses a mandatory configuration file (ldrs.cfg) to load all available plug-ins into the framework. In the LN DRS distribution one configuration file is provided which describes all plug-ins contained in the distribution. If a user implements additional plug-ins, a new extended version of this configuration file is needed.

Starting the Graphical User Interface

The graphical user interface is started with the command ldrs_gui. The user can provide the optional parameters described in table 1.

Table 1: Optional arguments for the GUI command.
CFG=<filename>	The name of the configuration file relative to the current directory. The file ldrs.cfg is the default.
/FORCE	If this flag is used, the configuration file will be loaded even if a configuration is already available.
RECIPE=<filename>	The name of a parameter file relative to the current directory.

Using the Pipeline in Batch Mode

The pipeline is started with the command ldrs_pipeline. The user can provide the optional parameters described in table 2.

Table 2: Optional arguments for the pipeline command.
CFG=<filename>	The name of the configuration file relative to the curent directory. The file ldrs.cfg is the default.
/FORCE	If this flag is used, the configuration will be loaded even if a configuration is already available.
RECIPE=<filename>	The name of a parameter file relative to the current directory.
PROC=<name> PROC=[<name1>, <name2>, ...]	The name or tag of one or more processing steps. They are executed in the given order.

It is possible to use the pipeline in a shell script by invoking it with

Source 1: Invoking the pipeline from a shell script.
echo "ldrs_pipeline, recipe='recipe.conf', proc='Calibration'" \| idl

which executes the calibration step of the first example in the tutorial. Alternatively, a short batch file can be created with the contents:

Source 2: Invoking the pipeline from an IDL startup file.
ldrs_pipeline, recipe='data/ngc4151/recipe.conf', proc='Calibration'

which is executed by starting the idl runtime environment after specifying that file as a startup file. An idl startup file is defined by setting the environment variable IDL_STARTUP to the filename (see the Introducing IDL/Startup Files chapter in the Using IDL manual).

The pipeline can be launched from the IDL command prompt with:

Source 3: Invoking the pipeline from the IDL command prompt.
ldrs_pipeline, $ recipe='/home/mhein/soft/lndrs/data/NGC4151/recipe.conf', $ proc=['CAL', 'PREP', 'TARCR', 'PSFCR', 'REC']

which executes the complete pipeline and produces a reconstruction.

Using the Configuration File Editor

If a user wants to extend the LN DRS (for example, implementing a new reconstruction algorithm), he has to modify the configuration file ldrs.cfg. A small application simplifies modification of this file. A screenshot of the configuration editor is presented in figure 1.

Figure 1: Configuration editor.

The configuration editor is launched from the command line with the command java -jar lndrs.jar. The jar file needed is provided in the distribution (see section Downloading the Software) and must be given as an argument to the java command.