Wish Effect black and white in B4XBitmapEffects

'calculates the mean scale value to generate a mean scaled image
Public Sub BlackAndWhite (Image As B4XBitmap, Threshold As Int) As B4XBitmap
    Private x, y, Mean, BWCol As Int
    Private col0, col1 As ARGBColor
    Private bmcImage, bmcResult As BitmapCreator
   
    bmcImage.Initialize(Image.Width, Image.Height)
    bmcImage.CopyPixelsFromBitmap(Image)
    bmcResult.Initialize(Image.Width, Image.Height)
   
    For y = 0 To Image.Height -1
        For x = 0 To Image.Width -1
            bmcImage.GetARGB(x, y, col0)
            col1.a = col0.a
            Mean = (col0.r + col0.g + col0.b) / 3
            If Mean >= Threshold Then
                BWCol = 255
            Else
                BWCol = 0
            End If          
            col1.r = BWCol
            col1.g = BWCol
            col1.b = BWCol
            bmcResult.SetARGB(x, y, col1)
        Next
    Next
    Return bmcResult.Bitmap
End Sub