使用c＃中的itextsharp从pdf中提取图像

Question

您好我正在使用

     public void ExtractImagesFromPDF(string sourcePdf, string outputPath)
    {
        // NOTE: This will only get the first image it finds per page.
        PdfReader pdf = new PdfReader(sourcePdf);
        RandomAccessFileOrArray raf = new iTextSharp.text.pdf.RandomAccessFileOrArray(sourcePdf);

        try
        {
            for (int pageNumber = 1; pageNumber <= pdf.NumberOfPages; pageNumber++)
            {
                Response.Write("Page " + pageNumber.ToString());
                PdfDictionary pg = pdf.GetPageN(pageNumber);

                // recursively search pages, forms and groups for images.
                PdfObject obj = FindImageInPDFDictionary(pg);

                if (obj != null)
                {

                    int XrefIndex = Convert.ToInt32(((PRIndirectReference)obj).Number.ToString(System.Globalization.CultureInfo.InvariantCulture));
                    PdfObject pdfObj = pdf.GetPdfObject(XrefIndex);
                    PdfStream pdfStrem = (PdfStream)pdfObj;
                    bytes = PdfReader.GetStreamBytesRaw((PRStream)pdfStrem);
                    if ((bytes != null))
                    {




                        using (System.IO.MemoryStream memStream = new System.IO.MemoryStream(bytes))
                        {
                            memStream.Seek(0, SeekOrigin.Begin);
                            memStream.Position = 0;
                            System.Drawing.Image img = System.Drawing.Image.FromStream(memStream);
                            // must save the file while stream is open.
                            if (!Directory.Exists(outputPath))
                                Directory.CreateDirectory(outputPath);

                            string path = System.IO.Path.Combine(outputPath, String.Format(@"{0}.jpg", pageNumber));
                            System.Drawing.Imaging.EncoderParameters parms = new System.Drawing.Imaging.EncoderParameters(1);
                            parms.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Compression, 0);
                            System.Drawing.Imaging.ImageCodecInfo jpegEncoder = GetEncoder(System.Drawing.Imaging.ImageFormat.Jpeg);
                            img.Save(path, jpegEncoder, parms);
                        }
                    }
                }
                else
                {
                }
            }
        }
        catch
        {
            throw;
        }
        finally
        {
            pdf.Close();
            raf.Close();
        }


    }

代码但不提取我的pdf文件，参数无效错误，我使用第三方dll用于提取图像所以从pdf获取所有图像但我想使用itextsharp dll，请检查并帮助我。< / p>