LowPassFilter Kernel

HI all, 

We realized that the outcome of the Low Pass filter changed from version 9.1.5 to 9.3. 

We use this script part below to subtract a low pass image from the original to correct background in some cases. 
(note that your inbuilt BG correction function do not always work on large images and even worse without throwing an error)

Anyway the method below leads to different results in the two version. 

Can we harmonize? Is there a way to get the Kernel into it? (did not find a valid command for that). 
Or is there a library I could add to 9.1.5?

Public Function LPBGCorrect() As SimpleScript
        LPBGCorrect = New SimpleScript

        Dim  doc3, image1, doc2, image2, window1,
     Dim LPFiltersize = 1001


        With Application.DocumentCommands.Active(LPBGCorrect)
            .Run(doc3)
        End With

        With Adjust.ImageCommands.Duplicate(LPBGCorrect)
            .Name = "Temp"
            .Visible = True
            .Run(doc3, image1)
        End With

        With Application.DocumentCommands.Activate(LPBGCorrect)
            .Run(image1, doc2)
        End With

        With Process.Filter.LargeCommands.LowPassLarge(LPBGCorrect)
            .Passes = 1
            .Width = LPFiltersize
            .Height = LPFiltersize
            .LockWidthHeight = True
            .Run(image1, image1)
        End With

        With Application.DocumentCommands.Activate(LPBGCorrect)
            .Run(doc3, doc3)
        End With

        With Process.ProcessCommands.Operations(LPBGCorrect)
            .Operation = eOperation.Subtract
            .NumberValue = 0R
            .ResultType = eResultType.Apply
            .Run(doc3, image1, image2)
        End With

        With Application.DocumentCommands.Activate(LPBGCorrect)
            .Run(doc2, doc2)
        End With

        With Application.WindowCommands.Define(LPBGCorrect)
            .Run(doc2, window1)
        End With

        With Application.WindowCommands.Close(LPBGCorrect)
            .Run(window1)
        End With

        With Application.DocumentCommands.Activate(LPBGCorrect)
            .Run(doc3, doc3)
        End With

    End Function

Many thanks

Daniel