Public Class Form1
 
	Private Sub cmd_einfügen_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles cmd_einfügen.Click
 
    	Dim input As String
 
    	Dim output As String
 
    	Dim water As String
 
 
 
    	input = "C:\hallo welt.pdf"
 
    	water = "C:\hintergrund.jpg"
 
    	output = "C:\ergebnis.pdf"
 
    	AddWatermarkImage(input, output, water)
 
 
 
	End Sub
 
	Public Shared Sub AddWatermarkImage(ByVal sourceFile As String, ByVal _
  outputFile As String, ByVal watermarkImage As String)
 
    	Dim reader As iTextSharp.text.pdf.PdfReader = Nothing
 
    	Dim stamper As iTextSharp.text.pdf.PdfStamper = Nothing
 
    	Dim img As iTextSharp.text.Image = Nothing
 
    	Dim underContent As iTextSharp.text.pdf.PdfContentByte = Nothing
 
    	Dim rect As iTextSharp.text.Rectangle = Nothing
 
    	Dim X, Y As Single
 
    	Dim pageCount As Integer = 0
 
 
    	Try
 
        	If System.IO.File.Exists(sourceFile) Then
 
            	reader = New iTextSharp.text.pdf.PdfReader(sourceFile)
 
            	rect = reader.GetPageSizeWithRotation(1)
 
            	stamper = New iTextSharp.text.pdf.PdfStamper(reader, New _
              System.IO.FileStream(outputFile, IO.FileMode.Create))
 
            	img = iTextSharp.text.Image.GetInstance(watermarkImage)
 
            	If img.Width > rect.Width OrElse img.Height > rect.Height Then
 
                	img.ScaleToFit(rect.Width, rect.Height)
 
                	X = (rect.Width - img.ScaledWidth) / 2
 
                	Y = (rect.Height - img.ScaledHeight) / 2
 
            	Else
 
                	X = (rect.Width - img.Width) / 2
 
                	Y = (rect.Height - img.Height) / 2
 
            	End If
 
            	img.SetAbsolutePosition(X, Y)
 
            	pageCount = reader.NumberOfPages()
 
            	For i As Integer = 1 To pageCount
 
                	underContent = stamper.GetUnderContent(i)
 
                	underContent.AddImage(img)
 
            	Next
 
            	stamper.Close()
 
            	reader.Close()
 
        	Else
 
            	MessageBox.Show("Deitei existiert nicht", "Datei?")
 
        	End If
 
    	Catch ex As Exception
 
        	Throw ex
 
    	End Try
 
	End Sub
End Class