vpCannyEdgeDetection.h

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2023 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */
 
#ifndef _vpCannyEdgeDetection_h_
#define _vpCannyEdgeDetection_h_
 
// System includes
#include <map>
#include <vector>
 
// ViSP include
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpImage.h>
#include <visp3/core/vpImageFilter.h>
 
// 3rd parties include
#ifdef VISP_HAVE_NLOHMANN_JSON
#include <nlohmann/json.hpp>
using json = nlohmann::json; 
#endif
 
class VISP_EXPORT vpCannyEdgeDetection
{
private:
  typedef enum EdgeType
  {
    STRONG_EDGE, 
    WEAK_EDGE,
    ON_CHECK 
  } EdgeType;
 
  // // Gaussian smoothing attributes
  int m_gaussianKernelSize; 
  float m_gaussianStdev;   
 
  // // Gradient computation attributes
  bool m_areGradientAvailable; 
  vpArray2D<float> m_fg; 
  vpArray2D<float> m_fgDg; 
  vpImage<float> m_dIx; 
  vpImage<float> m_dIy; 
 
  // // Edge thining attributes
  std::map<std::pair<unsigned int, unsigned int>, float> m_edgeCandidateAndGradient; 
 
  // // Hysteresis thresholding attributes
  float m_lowerThreshold; 
  float m_upperThreshold; 
 
  // // Edge tracking attributes
  std::map<std::pair<unsigned int, unsigned int>, EdgeType> m_edgePointsCandidates; 
  vpImage<unsigned char> m_edgeMap; 


  void initGaussianFilters();

  void performFilteringAndGradientComputation(const vpImage<unsigned char> &I);

  void performEdgeThining();

  void performHysteresisThresholding(const float &lowerThreshold, const float &upperThreshold);

  bool recursiveSearchForStrongEdge(const std::pair<unsigned int, unsigned int> &coordinates);

  void performEdgeTracking();
 
public:

  vpCannyEdgeDetection();

  vpCannyEdgeDetection(const int &gaussianKernelSize, const float &gaussianStdev,
                       const float &lowerThreshold = -1., const float &upperThreshold = -1.);
 
  // // Configuration from files
#ifdef VISP_HAVE_NLOHMANN_JSON
  vpCannyEdgeDetection(const std::string &jsonPath);

  void initFromJSON(const std::string &jsonPath);

  inline friend void from_json(const json &j, vpCannyEdgeDetection &detector)
  {
    detector.m_gaussianKernelSize = j.value("gaussianSize", detector.m_gaussianKernelSize);
    detector.m_gaussianStdev = j.value("gaussianStdev", detector.m_gaussianStdev);
    detector.m_lowerThreshold = j.value("lowerThreshold", detector.m_lowerThreshold);
    detector.m_upperThreshold = j.value("upperThreshold", detector.m_upperThreshold);
  }

  inline friend void to_json(json &j, const vpCannyEdgeDetection &detector)
  {
    j = json {
            {"gaussianSize", detector.m_gaussianKernelSize},
            {"gaussianStdev", detector.m_gaussianStdev},
            {"lowerThreshold", detector.m_lowerThreshold},
            {"upperThreshold", detector.m_upperThreshold} };
  }
#endif

#ifdef HAVE_OPENCV_CORE
  vpImage<unsigned char> detect(const cv::Mat &cv_I);
#endif

  vpImage<unsigned char> detect(const vpImage<vpRGBa> &I_color);

  vpImage<unsigned char> detect(const vpImage<unsigned char> &I);


  inline void setGradients(const vpImage<float> &dIx, const vpImage<float> &dIy)
  {
    m_dIx = dIx;
    m_dIy = dIy;
    m_areGradientAvailable = true;
  }

  inline void setCannyThresholds(const float &lowerThresh, const float &upperThresh)
  {
    m_lowerThreshold = lowerThresh;
    m_upperThreshold = upperThresh;
  }

  inline void setGaussianFilterParameters(const int &kernelSize, const float &stdev)
  {
    m_gaussianKernelSize = kernelSize;
    m_gaussianStdev = stdev;
    initGaussianFilters();
  }

};
#endif