iTextSharp：提取的CMYK图像被反转

Question

我一直在使用itextsharp从PDF中提取文本，我想提取所有图像，可能是灰度级JPG，CMYK JPG和PNG（根据itextsharp过滤器）。当我提取图像时，灰色JPG和PNG显示正确。然而，CMYK JPG看起来很奇怪，就像他们的颜色在提取后被倒置一样。这是我的代码：

internal class ImageRenderListener : IRenderListener
{
    #region Fields

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

    #endregion Fields

    #region Properties

    public List<System.Drawing.Image> Images
    {
        get { return images; }
    }

    #endregion Properties

    #region Methods

    #region Public Methods

    public void BeginTextBlock() { }

    public void EndTextBlock() { }

    public void RenderImage(ImageRenderInfo renderInfo)
    {
        PdfImageObject image = renderInfo.GetImage();
        PdfName filter = (PdfName)image.Get(PdfName.FILTER);

        //int width = Convert.ToInt32(image.Get(PdfName.WIDTH).ToString());
        //int bitsPerComponent = Convert.ToInt32(image.Get(PdfName.BITSPERCOMPONENT).ToString());
        //string subtype = image.Get(PdfName.SUBTYPE).ToString();
        //int height = Convert.ToInt32(image.Get(PdfName.HEIGHT).ToString());
        //int length = Convert.ToInt32(image.Get(PdfName.LENGTH).ToString());
        //string colorSpace = image.Get(PdfName.COLORSPACE).ToString();

        /* It appears to be safe to assume that when filter == null, PdfImageObject 
         * does not know how to decode the image to a System.Drawing.Image.
         * 
         * Uncomment the code above to verify, but when I've seen this happen, 
         * width, height and bits per component all equal zero as well. */
        if (filter != null)
        {

            System.Drawing.Image drawingImage = image.GetDrawingImage();
            var DimParams = renderInfo.GetImageCTM();

            string extension = string.Empty;

            if (filter == PdfName.DCTDECODE)
            {
                extension += PdfImageObject.ImageBytesType.JPG.FileExtension;

            }
            else if (filter == PdfName.JPXDECODE)
            {
                extension += PdfImageObject.ImageBytesType.JP2.FileExtension;
            }
            else if (filter == PdfName.FLATEDECODE)
            {
                extension += PdfImageObject.ImageBytesType.PNG.FileExtension;
            }
            else if (filter == PdfName.LZWDECODE)
            {
                extension += PdfImageObject.ImageBytesType.CCITT.FileExtension;
            }

            /* Rather than struggle with the image stream and try to figure out how to handle 
             * BitMapData scan lines in various formats (like virtually every sample I've found 
             * online), use the PdfImageObject.GetDrawingImage() method, which does the work for us. */

            Images.Add(drawingImage );
        }

    }

    public void RenderText(TextRenderInfo renderInfo) { }

    #endregion Public Methods

    #endregion Methods
}

我认为问题应该是流解码的方式，但我不明白如何解决这个问题。 感谢任何有想法的人。

这是提取的图像（已更新）：

这是PDF的链接 http://docdro.id/ZoHmiAd