openalpr-base/src/openalpr/ocr.cpp

/*
 * Copyright (c) 2015 New Designs Unlimited, LLC
 * Opensource Automated License Plate Recognition [http://www.openalpr.com]
 *
 * This file is part of OpenAlpr.
 *
 * OpenAlpr is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License
 * version 3 as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include "ocr.h"

using namespace std;
using namespace cv;
using namespace tesseract;

namespace alpr
{

  OCR::OCR(Config* config)
  : postProcessor(config)
  {
    const string EXPECTED_TESSERACT_VERSION = "3.03";

    this->config = config;


    if (startsWith(tesseract.Version(), EXPECTED_TESSERACT_VERSION) == false)
    {
      std::cerr << "Warning: You are running an unsupported version of Tesseract." << endl;
      std::cerr << "Expecting version " << EXPECTED_TESSERACT_VERSION << ", your version is: " << tesseract.Version() << endl;
    }

    // Tesseract requires the prefix directory to be set as an env variable
    tesseract.Init(config->getTessdataPrefix().c_str(), config->ocrLanguage.c_str() 	);
    tesseract.SetVariable("save_blob_choices", "T");
    tesseract.SetPageSegMode(PSM_SINGLE_CHAR);
  }

  OCR::~OCR()
  {
    tesseract.Clear();
  }

  void OCR::performOCR(PipelineData* pipeline_data)
  {
    timespec startTime;
    getTimeMonotonic(&startTime);

    postProcessor.clear();

    // Don't waste time on OCR processing if it is impossible to get sufficient characters
    if (pipeline_data->charRegions.size() < config->postProcessMinCharacters)
      return;

    for (unsigned int i = 0; i < pipeline_data->thresholds.size(); i++)
    {
      // Make it black text on white background
      bitwise_not(pipeline_data->thresholds[i], pipeline_data->thresholds[i]);
      tesseract.SetImage((uchar*) pipeline_data->thresholds[i].data, 
                          pipeline_data->thresholds[i].size().width, pipeline_data->thresholds[i].size().height, 
                          pipeline_data->thresholds[i].channels(), pipeline_data->thresholds[i].step1());

      for (unsigned int j = 0; j < pipeline_data->charRegions.size(); j++)
      {
        Rect expandedRegion = expandRect( pipeline_data->charRegions[j], 2, 2, pipeline_data->thresholds[i].cols, pipeline_data->thresholds[i].rows) ;

        tesseract.SetRectangle(expandedRegion.x, expandedRegion.y, expandedRegion.width, expandedRegion.height);
        tesseract.Recognize(NULL);

        tesseract::ResultIterator* ri = tesseract.GetIterator();
        tesseract::PageIteratorLevel level = tesseract::RIL_SYMBOL;
        do
        {
          const char* symbol = ri->GetUTF8Text(level);
          float conf = ri->Confidence(level);

          bool dontcare;
          int fontindex = 0;
          int pointsize = 0;
          const char* fontName = ri->WordFontAttributes(&dontcare, &dontcare, &dontcare, &dontcare, &dontcare, &dontcare, &pointsize, &fontindex);

          if(symbol != 0  && pointsize >= config->ocrMinFontSize)
          {
            postProcessor.addLetter(string(symbol), j, conf);

            if (this->config->debugOcr)
              printf("charpos%d: threshold %d:  symbol %s, conf: %f font: %s (index %d) size %dpx", j, i, symbol, conf, fontName, fontindex, pointsize);

            bool indent = false;
            tesseract::ChoiceIterator ci(*ri);
            do
            {
              const char* choice = ci.GetUTF8Text();

              postProcessor.addLetter(string(choice), j, ci.Confidence());

              //letterScores.addScore(*choice, j, ci.Confidence() - MIN_CONFIDENCE);
              if (this->config->debugOcr)
              {
                if (indent) printf("\t\t ");
                printf("\t- ");
                printf("%s conf: %f\n", choice, ci.Confidence());
              }

              indent = true;
            }
            while(ci.Next());
          }

          if (this->config->debugOcr)
            printf("---------------------------------------------\n");

          delete[] symbol;
        }
        while((ri->Next(level)));

        delete ri;
      }
    }

    if (config->debugTiming)
    {
      timespec endTime;
      getTimeMonotonic(&endTime);
      cout << "OCR Time: " << diffclock(startTime, endTime) << "ms." << endl;
    }
  }

}