Extract image from PDF

[programmersharp]

I have a PDF file that contains an image where this image is successfully displayed. When I try to extract the image from the PDF file I get bytes, then decode them successfully (because there is /Filter/FlateDecode there). But when I try to convert these bytes to an image using different libs the exception occured (it looks like the bytes are actually not an image). As far as I understand the problem is processing these bytes, but the image in the Pdf is not corrupted because it is shown there correctly. PDF is here.

        int pageNum = 1;
        PdfReader pdf = new PdfReader(filename);
        PdfDictionary pg = pdf.GetPageN(pageNum);
        PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES));
        PdfDictionary xobj = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT));
        if (xobj == null) { return ""; }

        foreach (PdfName name in xobj.Keys)
        {
            PdfObject obj = xobj.Get(name);
            if (!obj.IsIndirect()) { continue; }
            PdfDictionary tg = (PdfDictionary)PdfReader.GetPdfObject(obj);
            PdfName type = (PdfName)PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE));
            if (!type.Equals(PdfName.IMAGE)) { continue; }
            int XrefIndex = Convert.ToInt32(((PRIndirectReference)obj).Number.ToString(System.Globalization.CultureInfo.InvariantCulture));
            PdfObject pdfObj = pdf.GetPdfObject(XrefIndex);
            PdfStream pdfStrem = (PdfStream)pdfObj;
            byte[] bytes = PdfReader.GetStreamBytesRaw((PRStream)pdfStrem);
            if (bytes == null) { continue; }
            using (System.IO.MemoryStream memStream = new System.IO.MemoryStream(bytes))
            {
                memStream.Position = 0;

                byte[] decodedBytes = PdfReader.FlateDecode(bytes);

                /// Now libs can not process these decodedBytes as an image, exception occured.
            }
        }