Как сделать полупрозрачную картинку?

Sub Form2_Paint(sender As Object, e As PaintEventArgs) Handles MyBase.Paint
        Dim image1 As Image = Image.FromFile("red_impala.jpg")
        Dim destRect As New Rectangle(0, 0, SystemInformation.PrimaryMonitorSize.Width, SystemInformation.PrimaryMonitorSize.Height)
        e.Graphics.DrawImage(image1, destRect)
 
End Sub

Public Shared Function ChangeOpacity(ByVal img As Image, ByVal opacityvalue As Single) As Bitmap
        Dim bmp As New Bitmap(img.Width, img.Height)
        Dim graphics__1 As Graphics = Graphics.FromImage(bmp)
        Dim colormatrix As New System.Drawing.Imaging.ColorMatrix
        colormatrix.Matrix33 = opacityvalue
        Dim imgAttribute As New System.Drawing.Imaging.ImageAttributes
        imgAttribute.SetColorMatrix(colormatrix, System.Drawing.Imaging.ColorMatrixFlag.[Default], System.Drawing.Imaging.ColorAdjustType.Bitmap)
        graphics__1.DrawImage(img, New Rectangle(0, 0, bmp.Width, bmp.Height), 0, 0, img.Width, img.Height,
         GraphicsUnit.Pixel, imgAttribute)
        graphics__1.Dispose()
        Return bmp
    End Function