Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button3.Click
        f2.Show()
 
        Dim start As DateTime
        Dim stopp As DateTime
        start = DateTime.Now
         f2.PictureBox3.Image = BitmapDiff(CType(PictureBox1.Image, Bitmap), _
           CType(PictureBox2.Image, Bitmap))
        stopp = DateTime.Now
        Dim dif As TimeSpan
        dif = stopp.Subtract(start)
        MsgBox("Dauer " & dif.Minutes & ":" & dif.Seconds & "," & _
          dif.Milliseconds)
 
    End Sub