Method RecognizeSegment

deps/tesseract/cube/cube_search_object.cpp:240–293

call from Beam Search to return the alt list corresponding to recognizing the bitmap between two segmentation pts

// call from Beam Search to return the alt list corresponding to
// recognizing the bitmap between two segmentation pts
CharAltList * CubeSearchObject::RecognizeSegment(int start_pt, int end_pt) {
  // init if necessary
  if (!init_ && !Init()) {
    fprintf(stderr, "Cube ERROR (CubeSearchObject::RecognizeSegment): could "
            "not initialize CubeSearchObject\n");
    return NULL;
  }

  // validate segment range
  if (!IsValidSegmentRange(start_pt, end_pt)) {
    fprintf(stderr, "Cube ERROR (CubeSearchObject::RecognizeSegment): invalid "
            "segment range (%d, %d)\n", start_pt, end_pt);
    return NULL;
  }

  // look for the recognition results in cache in the cache
  if (reco_cache_ && reco_cache_[start_pt + 1] &&
      reco_cache_[start_pt + 1][end_pt]) {
    return reco_cache_[start_pt + 1][end_pt];
  }

  // create the char sample corresponding to the blob
  CharSamp *samp = CharSample(start_pt, end_pt);
  if (!samp) {
    fprintf(stderr, "Cube ERROR (CubeSearchObject::RecognizeSegment): could "
            "not construct CharSamp\n");
    return NULL;
  }

  // recognize the char sample
  CharClassifier *char_classifier = cntxt_->Classifier();
  if (char_classifier) {
    reco_cache_[start_pt + 1][end_pt] = char_classifier->Classify(samp);
  } else {
    // no classifer: all characters are equally probable; add a penalty
    // that favors 2-segment characters and aspect ratios (w/h) > 1
    fprintf(stderr, "Cube WARNING (CubeSearchObject::RecognizeSegment): cube "
            "context has no character classifier!! Inventing a probability "
            "distribution.\n");
    int class_cnt = cntxt_->CharacterSet()->ClassCount();
    CharAltList *alt_list = new CharAltList(cntxt_->CharacterSet(), class_cnt);
    int seg_cnt = end_pt - start_pt;
    double prob_val = (1.0 / class_cnt) *
        exp(-fabs(seg_cnt - 2.0)) *
        exp(-samp->Width() / static_cast<double>(samp->Height()));

    for (int class_idx = 0; class_idx < class_cnt; class_idx++) {
      alt_list->Insert(class_idx, CubeUtils::Prob2Cost(prob_val));
    }
    reco_cache_[start_pt + 1][end_pt] = alt_list;
  }

  return reco_cache_[start_pt + 1][end_pt];
}

// Perform segmentation of the bitmap by detecting connected components,
// segmenting each connected component using windowed vertical pixel density