Вызов функции из dll. Dll не определена в коде и подключается программно

Function Negative(ByVal Bmp As Bitmap)
        Dim Bmp2 As New Bitmap(Bmp.Width, Bmp.Height)
        Dim C As Color
        For y = 0 To Bmp2.Height - 1
            For x = 0 To Bmp2.Width - 1
                C = Bmp.GetPixel(x, y)
                Bmp2.SetPixel(x, y, Color.FromArgb(255 - C.R, 255 - C.G, 255 - C.B))
            Next
        Next
        Return Bmp2
End Function

Public Class Class1
Function Negative(ByVal Bmp As Bitmap)
        Dim Bmp2 As New Bitmap(Bmp.Width, Bmp.Height)
        Dim C As Color
        For y = 0 To Bmp2.Height - 1
            For x = 0 To Bmp2.Width - 1
                C = Bmp.GetPixel(x, y)
                Bmp2.SetPixel(x, y, Color.FromArgb(255 - C.R, 255 - C.G, 255 - C.B))
            Next
        Next
        Return Bmp2
End Function
End Class

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.BackgroundImage = Negative(Me.BackgroundImage)
End Sub

Class1.Negative........

Imports<Библа>

Dim MyLib As New <Твоя библа>

Me.BackgroundImage = MyLib.Negative(Me.BackgroundImage)

IO.Directory.GetFiles("Effect", "*.dll", IO.SearchOption.TopDirectoryOnly)