Extract image from PDF using itextsharp

I am trying to extract all the images from a pdf using itextsharp but can't seem to overcome this one hurdle.

The error occures on the line System.Drawing.Image ImgPDF = System.Drawing.Image.FromStream(MS); giving an error of "Parameter is not valid".

I think it works when the image is a bitmap but not of any other format.

I have this following code - sorry for the length;

    private void Form1_Load(object sender, EventArgs e)
    {
        FileStream fs = File.OpenRead(@"reader.pdf");
        byte[] data = new byte[fs.Length];
        fs.Read(data, 0, (int)fs.Length);

        List<System.Drawing.Image> ImgList = new List<System.Drawing.Image>();

        iTextSharp.text.pdf.RandomAccessFileOrArray RAFObj = null;
        iTextSharp.text.pdf.PdfReader PDFReaderObj = null;
        iTextSharp.text.pdf.PdfObject PDFObj = null;
        iTextSharp.text.pdf.PdfStream PDFStremObj = null;

        try
        {
            RAFObj = new iTextSharp.text.pdf.RandomAccessFileOrArray(data);
            PDFReaderObj = new iTextSharp.text.pdf.PdfReader(RAFObj, null);

            for (int i = 0; i <= PDFReaderObj.XrefSize - 1; i++)
            {
                PDFObj = PDFReaderObj.GetPdfObject(i);

                if ((PDFObj != null) && PDFObj.IsStream())
                {
                    PDFStremObj = (iTextSharp.text.pdf.PdfStream)PDFObj;
                    iTextSharp.text.pdf.PdfObject subtype = PDFStremObj.Get(iTextSharp.text.pdf.PdfName.SUBTYPE);

                    if ((subtype != null) && subtype.ToString() == iTextSharp.text.pdf.PdfName.IMAGE.ToString())
                    {
                        byte[] bytes = iTextSharp.text.pdf.PdfReader.GetStreamBytesRaw((iTextSharp.text.pdf.PRStream)PDFStremObj);

                        if ((bytes != null))
                        {
                            try
                            {
                                System.I