Declaration: TMetaData.InvertPixMask (ixMask: integer): integer;
Inverts the pixel mask specified by the parameter ixMask (valid range 1..32). The function returns the following error codes:
 0 .... everything OK
-1 ... specified mask does not exist

Hint: In order to directly access the metadata of the currently loaded dataset you can use the pre-declared global variable MData.