public static void ConvertPdf2Image(string pdfFilePath, string imageDirectoryPath,int beginPageNum, int endPageNum, ImageFormat format, double zoom = 1) {

            Acrobat.CAcroPDDoc pdfDoc = null;            Acrobat.CAcroPDPage pdfPage = null;            Acrobat.CAcroRect pdfRect = null;            Acrobat.CAcroPoint pdfPoint = null;

//1)            //生成操作Pdf文件的Com对象              pdfDoc = (Acrobat.CAcroPDDoc)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.PDDoc", "");

//检查输入参数              if (!pdfDoc.Open(pdfFilePath)) {throw new FileNotFoundException(string.Format("源文件{0}不存在！", pdfFilePath));            }

if (!Directory.Exists(imageDirectoryPath)) {                Directory.CreateDirectory(imageDirectoryPath);            }

if (beginPageNum <= 0) {                beginPageNum = 1;            }

if (endPageNum > pdfDoc.GetNumPages() || endPageNum <= 0) {                endPageNum = pdfDoc.GetNumPages();            }

if (beginPageNum > endPageNum) {throw new ArgumentException("参数\"beginPageNum\"必须小于\"endPageNum\"！");            }

if (format == null) {                format = ImageFormat.Png;            }

if (zoom <= 0) {                zoom = 1;            }

//转换              for (int i = beginPageNum; i <= endPageNum; i++) {//2)//取出当前页                  pdfPage = (Acrobat.CAcroPDPage)pdfDoc.AcquirePage(i - 1);

//3)//得到当前页的大小                   pdfPoint = (Acrobat.CAcroPoint)pdfPage.GetSize();//生成一个页的裁剪区矩形对象                   pdfRect = (Acrobat.CAcroRect)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.Rect", "");

//计算当前页经缩放后的实际宽度和高度,zoom==1时，保持原比例大小                   int imgWidth = (int)((double)pdfPoint.x * zoom);int imgHeight = (int)((double)pdfPoint.y * zoom);

//设置裁剪矩形的大小为当前页的大小                   pdfRect.Left = 0;                pdfRect.right = (short)imgWidth;                pdfRect.Top = 0;                pdfRect.bottom = (short)imgHeight;

//4)//将当前页的裁剪区的内容编成图片后复制到剪贴板中                  pdfPage.CopyToClipboard(pdfRect, 0, 0, (short)(100 * zoom));

//5)                IDataObject clipboardData = Clipboard.GetDataObject();

//检查剪贴板中的对象是否是图片，如果是图片则将其保存为指定格式的图片文件                  if (clipboardData.GetDataPresent(DataFormats.Bitmap)) {                    Bitmap pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);

                    pdfBitmap.Save(                        Path.Combine(imageDirectoryPath, i.ToString("0000") + "." + format.ToString()), format);

                    pdfBitmap.Dispose();                }            }

//关闭和释放相关COM对象              pdfDoc.Close();            Marshal.ReleaseComObject(pdfRect);            Marshal.ReleaseComObject(pdfPoint);            Marshal.ReleaseComObject(pdfPage);            Marshal.ReleaseComObject(pdfDoc);        }