放大Tesseract OCR的边界矩形

Question

我使用Tesseract OCR和OpenCV从Mat图像中获取数字，特别是零，但经常发生Tesseract没有以正确的方式识别零。我认为这是因为边界矩形太小而削减了数字的一部分，所以这是一个＆＃39; 0＆＃39;成了一个＆＃39; c＆＃39;或者是＆＃39; n。 有办法扩大边界矩形吗？这是我的代码：

int main()
{
  Mat img1 = imread("Input/05.png");
  cvtColor(img1, img1, CV_BGR2GRAY);
  Size size(img1.cols*1.5,img1.rows*1.5);
  Mat img;
  resize(img1, img, size);
  //pre-processing start

  IplImage* image = new IplImage(img);
  IplImage* bWImage = cvCreateImage(cvGetSize(image), IPL_DEPTH_8U, 1);
  cvThreshold(image, bWImage, 180, 255, THRESH_BINARY);
  Mat patch = cvarrToMat(bWImage, true);

  //pre-processing end

  tesseract::TessBaseAPI *api = new tesseract::TessBaseAPI();
  api->Init(NULL, "eng");
  api->SetImage((uchar*)patch.data, patch.cols, patch.rows, 1, patch.cols);
  //api->SetVariable("classify_bln_numeric_mode", "1");
  //api->SetRectangle(30, 400, 400, 40);
  api->Recognize(NULL);

  tesseract::ResultIterator* ri = api->GetIterator();
  tesseract::PageIteratorLevel level = tesseract::RIL_WORD;
  vector<Point> points;
  if (ri != 0){
     do {
       const char* word = ri->GetUTF8Text(level);
       float conf = ri->Confidence(level);
       int x1, y1, x2, y2;
       if(word != 0){
          ri->BoundingBox(level, &x1, &y1, &x2, &y2);
          rectangle(patch, Point(x1,y1), Point(x2,y2), 0, 1, 8);
          imshow("Zero", patch);
          waitKey();
          printf("word: '%s';  \tconf: %.2f; BoundingBox: %d,%d,%d,%d;\n", word, conf, x1, y1, x2, y2);
       }
       delete[] word;
     } while (ri->Next(level));
 }
}