BitmapSource image = BitmapSource.Create(
    width,
    height,
    96,
    96,
    PixelFormats.Indexed1,
    myPalette,
    pixels,
    stride);

FileStream stream = new FileStream("new.jpg", FileMode.Create);
JpegBitmapEncoder encoder = new JpegBitmapEncoder();
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString();
encoder.FlipHorizontal = true;
encoder.FlipVertical = false;
encoder.QualityLevel = 30;
encoder.Rotation = Rotation.Rotate90;
encoder.Frames.Add(BitmapFrame.Create(image));
encoder.Save(stream);