slic.h

#ifndef SLIC_H
#define SLIC_H

/* slic.h.
 *
 * Written by: Pascal Mettes.
 * and adapted by using the DGtal library (see. http://libdgtal.org and https://github.com/DGtal-team/DGtal)
 *
 * This file contains the class elements of the class Slic. This class is an
 * implementation of the SLIC Superpixel algorithm by Achanta et al. [PAMI'12,
 * vol. 34, num. 11, pp. 2274-2282].
 *
 * This implementation is created for the specific purpose of creating
 * over-segmentations in an OpenCV-based environment.
 */


#include "DGtal/base/Common.h"
#include "DGtal/helpers/StdDefs.h"
#include "DGtal/images/ImageContainerBySTLVector.h"


typedef struct CvScalar {
  double val[4];
} CvScalar;



typedef struct ToCvScalarFct{
  inline
  CvScalar operator() (unsigned int aVal) const
  {
    CvScalar result;
    DGtal::Color c (aVal, 255);
    result.val[0] = (double)(c.red());
    result.val[1] = (double)(c.green());
    result.val[2] = (double)(c.blue());
    return result;
  }
  
} ToCvScalarFct;

#define NR_ITERATIONS 10


typedef std::vector<std::vector<double> >  vec2dd;
typedef std::vector<std::vector<int> >  vec2di;
typedef std::vector<std::vector<bool> > vec2db;


typedef  DGtal::ImageContainerBySTLVector<DGtal::Z2i::Domain, unsigned int> Image2D;


class Slic{
  
private:
  /* The cluster assignments and distance values for each pixel. */
  vec2di clusters;
  vec2dd distances;
        
  /* The LAB and xy values of the centers. */
  vec2dd centers;
  /* The number of occurences of each center. */

  std::vector<int> center_counts;
        
  /* The step size per cluster, and the colour (nc) and distance (ns)
   * parameters. */
  int step, nc, ns;
        
  /* Compute the distance between a center and an individual pixel. */
  double compute_dist(int ci, DGtal::Z2i::Point pixel,CvScalar colour);
  /* Find the pixel with the lowest gradient in a 3x3 surrounding. */
  DGtal::Z2i::Point find_local_minimum(Image2D &image, DGtal::Z2i::Point center);
        
  /* Remove and initialize the 2d vectors. */
  void clear_data();
  void init_data(Image2D &image);

public:
  /* Class constructors and deconstructors. */
  Slic();
  ~Slic();
        
  /* Generate an over-segmentation for an image. */
  void generate_superpixels(Image2D &, int step, int nc);
  /* Enforce connectivity for an image. */
  void create_connectivity(Image2D &image);
        
  /* Draw functions. Resp. displayal of the centers and the contours. */
  void display_center_grid( Image2D &image, DGtal::Color &colour);
  void display_contours( Image2D &image, DGtal::Color &colour);
  void colour_with_cluster_means(Image2D &image);
};

#endif