private void writeThisImageTo(BitmapSource bitmap, String filename)
{
// open a stream
FileStream stream = new FileStream(filename, FileMode.Create);
// create an encoder
JpegBitmapEncoder encoder = new JpegBitmapEncoder();
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author;
// add the bitmap to the frame
encoder.Frames.Add(BitmapFrame.Create(bitmap));
encoder.Save(stream);
// close the stream
stream.Close();
}