Using g As Graphics = Graphics.FromImage(vorschau1)
   g.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
   g.DrawImage(vorschau, 0, 0, vorschau.Width, vorschau.Height)
End Using

Dim EncoderParameters As New Drawing.Imaging.EncoderParameters(1)
EncoderParameters.Param(0) = New Drawing.Imaging.EncoderParameter _
(Drawing.Imaging.Encoder.Quality, Quality)
 
vorschau1.Save(Filename, EncoderInfo("JPEG"), EncoderParameters)

Private Function EncoderInfo _
       (ByVal FormatDescriptor As String) As Drawing.Imaging.ImageCodecInfo
 
        ' Formatdescriptoren: BMP JPEG GIF TIFF PNG
 
    Dim i As Integer = 0
    Dim encoders() As Drawing.Imaging.ImageCodecInfo = _
          Drawing.Imaging.ImageCodecInfo.GetImageEncoders()
 
    FormatDescriptor = Trim(UCase(FormatDescriptor))
 
    While i < encoders.Length
       If UCase(encoders(i).FormatDescription) = FormatDescriptor Then
          Return encoders(i)
       End If
       i += 1
    End While
    Return Nothing
 End Function