Определить яркость пикселя в HSB

Private Sub Command_Button_Click(ByVal sender _
 As System.Object, ByVal e As System.EventArgs) Handles Command_Button.Click
        Dim c As Object
        Dim n, i, j As Integer
        Dim r, g, b As Integer
        Dim m As Bitmap
        Dim p As New Point(i, j)
        'n = FreeFile()
        'FileOpen(n, TextBox1.Text, OpenMode.Random)
        m = Image.FromFile(TextBox1.Text)
        Dim l As Color
        Dim k As New hsbcolor(l)
        PictureBox1.ImageLocation = TextBox1.Text
        For i = 1 To m.Width
            For j = 1 To m.Height
                l = m.GetPixel(i, j)
            Next
        Next
        'FileClose(n)
    End Sub

Dim pxRGB As Color = Color.FromArgb(196, 194, 194)
Dim pxH As Single = pxRGB.GetHue
Dim pxS As Single = pxRGB.GetSaturation
Dim pxB As Single = pxRGB.GetBrightness
Dim ss As String = "Hue (цветовой тон; 0-360) = " & pxH.ToString & vbCrLf & _
                    "Saturation (насыщенность; 0-1) = " & pxS.ToString & vbCrLf & _
                    "Brightness (яркость; 0-1) = " & pxB.ToString
MsgBox(ss)