Public Function SetImageAlpha(ByVal Image As Image, ByVal Alpha As Single) As _
   Image
        Dim ImgAttr As New Imaging.ImageAttributes()
 
      [u]  'Standard-ColorMatrix für Transparenz
        Dim ColorMatrix As New Imaging.ColorMatrix(New Single()() {New Single() _
          {1, 0, 0, 0, 0}, New Single() {0, 1, 0, 0, 0}, New Single() {0, 0, 1, _
          0, 0}, New Single() {0, 0, 0, CSng(Alpha / 100), 0}, New Single() {0, _
          0, 0, 0, 1}})  
 
        'ColorMatrix an ImageAttribute-Objekt übergeben
        ImgAttr.SetColorMatrix(ColorMatrix)
 
        'Neue 32bit Bitmap erstellen
        Dim NewBitmap = New Bitmap(Image.Width, Image.Height, _
          System.Drawing.Imaging.PixelFormat.Format32bppArgb)
 
        'Resolution (DPI) vom Quellbitmap auf Zielbitmap übertragen
        NewBitmap.SetResolution(Image.HorizontalResolution, _
          Image.VerticalResolution)
 
        'Graphicsobjekt von NewBitmap erstellen
        Dim NewGraphics As Graphics = Graphics.FromImage(NewBitmap)
 
        'NewBitmap auf NewGraphics zeichnen
        NewGraphics.DrawImage(Image, New Rectangle(0, 0, NewBitmap.Width, _
          NewBitmap.Height), 0, 0, Image.Width, Image.Height, _
          GraphicsUnit.Pixel, ImgAttr)
 
        'Ressource freigeben
        NewGraphics.Dispose()
        ImgAttr.Dispose()
        Return NewBitmap
    End Function