# Welcome to Preprocessor

Preprocessing concerns all the tasks necessary to prepare the data for data analysis. In this graphical interface, preprocessing images is done with `spd` program.
`Spd` is written in `C`and is maintained by Rainer Wilcke (wilcke@esrf.fr). It was originally written by Jorg Klora. `Spd` has many options and they can be seen by running spd without any arguments on the command line.
The fable preprocessor calls `spd` via its command line interface.
`Preprocessor` can be launched online mode, that means during image file acquired on the beamline ID11, or offline mode, that allows user to process image files on their own computer.
For more information about `Preprocessor` and `spd` options refer to the preprocessor wiki or use the online help : Help -> Help Contents.
`Preprocessor` and its graphical user interface application are part of the Fable project.