在PDF文件進(jìn)行掃描的時(shí)候，有時(shí)PDF中會有一些空白頁存在，掃描出來也是空白的，所以在掃描前往往需要加載GdPicture.NET，先一頁一頁的進(jìn)行檢查，這樣往往會很麻煩，實(shí)際上在使用GdPicture.NET的時(shí)候，只需要幾段簡單的代碼，就可以除去PDF中的空白頁，這里提供一段示例代碼，適用于GdPicture.NET 8.5.3或者更高的版本。

const int RASTER_DPI = 200;
            GdPictureImaging oGdPictureImaging = new GdPictureImaging();
            GdPicturePDF oGdPicturePDF = new GdPicturePDF();
            oGdPicturePDF.LoadFromFile(@"c:\input.pdf", false);
            oGdPicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitPoint);
            oGdPicturePDF.EnableCompression(true);
            for (int i = 1; i <= oGdPicturePDF.GetPageCount(); i++)
            {
                oGdPicturePDF.SelectPage(i);
                int rasterImageID = oGdPicturePDF.RenderPageToGdPictureImageEx(RASTER_DPI, false);
                int bitDepth = oGdPictureImaging.GetBitDepth(rasterImageID);
                if (oGdPictureImaging.IsBlank(rasterImageID))
                {
                    //page is blank, we remove it
                    oGdPicturePDF.DeletePage(i--);
                }
                else
                {
                    //if the page is based on a single color image, we convert it to 1bpp. Warning: not 100% safe
                    if (bitDepth > 8 && !oGdPicturePDF.PageHasText() && !oGdPicturePDF.PageHasShape() && oGdPicturePDF.GetPageImageCount() == 1)
                    {
                        if (oGdPictureImaging.ConvertTo1BppAT(rasterImageID) == GdPictureStatus.OK)
                        {
                            //we remove the page then create a new one to remove unused resources on pack
                            float pageWidth = oGdPicturePDF.GetPageWidth();
                            float pageHeight = oGdPicturePDF.GetPageHeight();
                            oGdPicturePDF.DeletePage(i);
                            oGdPicturePDF.InsertPage(pageWidth, pageHeight, i);
                            string pdfImageResName = oGdPicturePDF.AddImageFromGdPictureImage(rasterImageID, false, false);
                            if (pdfImageResName != "")
                            {
                                oGdPicturePDF.DrawImage(pdfImageResName, 0, 0, pageWidth, pageHeight);
                            }
                            else
                            {
                                throw new Exception("Error embedding bitmap in PDF");
                            }
                        }
                        else
                        {
                            throw new Exception("Error during bitmap thresholding");
                        }
                    }
                }
                oGdPictureImaging.ReleaseGdPictureImage(rasterImageID);
            }
            oGdPicturePDF.SaveToFile(@"c:\newpdf.pdf", true); //we have to pack the doc to remove unused enbedded bitmaps
            oGdPicturePDF.CloseDocument();