在GdPicture.NET控件中提供了OCR识别模块，利用该模块可以对图片、PDF、TIFF等文件进行文本的识别，支持多达50多种语言，如：英语、法语、意大利、德语、西班牙语、中文等，在识别时不仅可以进行多页完整识别，还可以对指定区域进行文本的识别，这篇文章主要介绍如何利用该产品对PDF文件中指定区域的识别，具体代码如下：

GdPictureImaging oGdPictureImaging = new GdPictureImaging();
GdPicturePDF oGdPicturePDF = new GdPicturePDF();
int rasterPageID = 0;

//Loading PDF
if (oGdPicturePDF.LoadFromFile("input.pdf", false) == GdPictureStatus.OK) {
   //Selecting first page
   oGdPicturePDF.SelectPage(1);
   //rendering page to a 200 DPI image
   rasterPageID = oGdPicturePDF.RenderPageToGdPictureImage(200, true);
   if (rasterPageID != 0) {
      //setting the Area to be OCRed
      oGdPictureImaging.SetROI(0, 0, 1000, 1000);
      // here we make a region of interest from (0, 0) to (1000, 1000)
      //setting the OCR context
      oGdPictureImaging.OCRTesseractSetOCRContext(OCRContext.OCRContextDocument);
      //You can use another context if possible. This can increase accuracy
      string sOCR = oGdPictureImaging.OCRTesseractDoOCR(rasterPageID, "eng", "C:\\Path\\To\\GdPicture.NET 10\\Redist\

\OCR", "");
      if (oGdPictureImaging.GetStat() == GdPictureStatus.OK) {
         MessageBox.Show(sOCR);
      } else {
         MessageBox.Show(oGdPictureImaging.GetStat().ToString());
      }
   } else {
      MessageBox.Show(oGdPicturePDF.GetStat().ToString());
   }
//closing the pdf
   oGdPicturePDF.CloseDocument();
}
//Clearing resources
oGdPictureImaging.ReleaseGdPictureImage(rasterPageID);