For y As Integer = 0 To b1.Height - 1
            For x As Integer = 0 To b1.Width - 1
                If b1.GetPixel(x, y) <> b2.GetPixel(x, y) Then
                    bm.SetPixel(x, y, Color.Black)
                Else
                    bm.SetPixel(x, y, Color.White)
 
                End If