Declaration: SubtractExtData(ExtDataFName: string; Feedback: boolean): integer;
Subtracts the data cube stored in the file ExtDataFName from the data currently in memory. This procedure does not use any extra memory for the external file.

The parameter Feedback controls whether Epina ImageLab provides a visual feedback of the progress. Please note that unless the script progress bar is already visible you have to make it visible before calling SubtractExtData, otherwise the feedback will not be displayed. You can activate the script progress bar by calling the function ScriptBar(0).

The function returns the following error codes:

 0 ... everything OK, the external data cube has been subtracted
-1 ... the external data set does not match the currently loaded data
-2 ... the file specified by ExtDataFName does not exist