Private Sub PDF2Tiff(ByVal qPfad As String, ByVal zpfad As String)
        Dim tiff As Image = Nothing

        Using doc = Patagames.Pdf.Net.PdfDocument.Load(qPfad)
            Dim dpi As Integer = 96
            Dim i As Integer = 1

            For Each page In doc.Pages
                Dim width As Integer = CInt((page.Width / 72.0 * dpi))
                Dim height As Integer = CInt((page.Height / 72.0 * dpi))

                Using bitmap = New Patagames.Pdf.Net.PdfBitmap(width, height, True)
                    bitmap.FillRect(0, 0, width, height, Patagames.Pdf.FS_COLOR.White)
                    page.Render(bitmap, 0, 0, width, height, Patagames.Pdf.Enums.PageRotate.Normal, Patagames.Pdf.Enums.RenderFlags.FPDF_LCD_TEXT)

                    If tiff Is Nothing Then
                        tiff = CreateTiffFromBitmap(bitmap.Image, zpfad)
                    Else
                        AddFrameToTiff(tiff, bitmap.Image)
                    End If
                End Using

                page.Dispose()
                Console.WriteLine(String.Format("Process page {0}", Math.Min(System.Threading.Interlocked.Increment(i), i - 1)))
            Next

            If tiff IsNot Nothing Then FlushTiff(tiff)
        End Using
    End Sub

    Public Function CreateTiffFromBitmap(ByVal bitmap As Image, ByVal pathToTiff As String) As Image
        Using byteStream As MemoryStream = New MemoryStream()
            bitmap.Save(byteStream, ImageFormat.Tiff)
            Dim tiff As Image = Image.FromStream(byteStream)
            Dim encoderInfo As ImageCodecInfo = ImageCodecInfo.GetImageEncoders().First(Function(i) i.MimeType = "image/tiff")
            Dim encoderParams As EncoderParameters = New EncoderParameters(2)
            Dim parameter As EncoderParameter = New EncoderParameter(Encoder.Compression, CLng(EncoderValue.CompressionLZW))
            encoderParams.Param(0) = parameter
            parameter = New EncoderParameter(Encoder.SaveFlag, CLng(EncoderValue.MultiFrame))
            encoderParams.Param(1) = parameter
            Dim ret = New MemoryStream()
            tiff.Save(pathToTiff, encoderInfo, encoderParams)
            Return tiff
        End Using
    End Function

    Public Sub AddFrameToTiff(ByVal tiff As Image, ByVal bitmap As Image)
        Dim EncoderParams As EncoderParameters = New EncoderParameters(3)
        Dim SaveEncodeParam As EncoderParameter = New EncoderParameter(Encoder.SaveFlag, CLng(EncoderValue.FrameDimensionPage))
        Dim CompressionEncodeParam As EncoderParameter = New EncoderParameter(Encoder.Compression, CLng(EncoderValue.CompressionLZW))
        Dim QualityEncodeParam As EncoderParameter = New EncoderParameter(Encoder.Quality, 100L)
        EncoderParams.Param(0) = CompressionEncodeParam
        EncoderParams.Param(1) = SaveEncodeParam
        EncoderParams.Param(2) = QualityEncodeParam
        tiff.SaveAdd(bitmap, EncoderParams)
    End Sub

    Public Sub FlushTiff(ByVal tiff As Image)
        Dim SaveEncodeParam As EncoderParameter = New EncoderParameter(Encoder.SaveFlag, CLng(EncoderValue.Flush))
        Dim EncoderParams = New EncoderParameters(1)
        EncoderParams.Param(0) = SaveEncodeParam
        tiff.SaveAdd(EncoderParams)
    End Sub