PTdecode/CImg-1.3.0/examples/mcf_levelsets.cpp

/*
 #
 #  File        : mcf_levelsets.cpp
 #                ( C++ source file )
 #
 #  Description : Implementation of the Mean Curvature Flow (classical 2d curve evolution),
 #                using the framework of Level Sets.
 #                This file is a part of the CImg Library project.
 #                ( http://cimg.sourceforge.net )
 #
 #  Copyright   : David Tschumperle
 #                ( http://www.greyc.ensicaen.fr/~dtschump/ )
 #
 #  License     : CeCILL v2.0
 #                ( http://www.cecill.info/licences/Licence_CeCILL_V2-en.html )
 #
 #  This software is governed by the CeCILL  license under French law and
 #  abiding by the rules of distribution of free software.  You can  use,
 #  modify and/ or redistribute the software under the terms of the CeCILL
 #  license as circulated by CEA, CNRS and INRIA at the following URL
 #  "http://www.cecill.info".
 #
 #  As a counterpart to the access to the source code and  rights to copy,
 #  modify and redistribute granted by the license, users are provided only
 #  with a limited warranty  and the software's author,  the holder of the
 #  economic rights,  and the successive licensors  have only  limited
 #  liability.
 #
 #  In this respect, the user's attention is drawn to the risks associated
 #  with loading,  using,  modifying and/or developing or reproducing the
 #  software by the user in light of its specific status of free software,
 #  that may mean  that it is complicated to manipulate,  and  that  also
 #  therefore means  that it is reserved for developers  and  experienced
 #  professionals having in-depth computer knowledge. Users are therefore
 #  encouraged to load and test the software's suitability as regards their
 #  requirements in conditions enabling the security of their systems and/or
 #  data to be ensured and,  more generally, to use and operate it in the
 #  same conditions as regards security.
 #
 #  The fact that you are presently reading this means that you have had
 #  knowledge of the CeCILL license and that you accept its terms.
 #
*/

#include "CImg.h"
using namespace cimg_library;

// The lines below are necessary when using a non-standard compiler as visualcpp6.
#ifdef cimg_use_visualcpp6
#define std
#endif
#ifdef min
#undef min
#undef max
#endif

// get_level0() : Retrieve the curve corresponding to the zero level set of the distance function
//-------------
CImg<unsigned char> get_level0(const CImg<>& img) {
  CImg<unsigned char> dest(img);
  CImg_2x2(I,float); Inn = 0;
  cimg_for2x2(img,x,y,0,0,I) if (Icc*Inc<0 || Icc*Icn<0) dest(x,y) = 255; else dest(x,y) = Icc<0?100:0;
  return dest;
}

//-----------------
// Main procedure
//-----------------
int main(int argc,char **argv) {
  cimg_usage("Perform a Mean Curvature Flow on closed curves, using Level Sets");
  const float dt = cimg_option("-dt",0.8f,"PDE time step");
  const unsigned int nb_iter = cimg_option("-iter",10000,"Number of iterations");

  // Create a user-defined closed curve
  CImg<unsigned char> curve(256,256,1,2,0);
  unsigned char col1[2]={0,255}, col2[2]={200,255}, col3[2]={255,255};
  curve.draw_grid(20,20,0,0,false,false,col1,0.4f,0xCCCCCCCC,0xCCCCCCCC).
    draw_text(5,5,"Please draw your curve\nin this window\n(Use your mouse)",col1);
  CImgDisplay disp(curve,"Mean curvature flow",0);
  int xo=-1,yo=-1,x0=-1,y0=-1,x1=-1,y1=-1;
  while (!disp.is_closed && (x0<0 || disp.button)) {
    if (disp.button && disp.mouse_x>=0 && disp.mouse_y>=0) {
      if (x0<0) { xo = x0 = disp.mouse_x; yo = y0 = disp.mouse_y; } else {
        x1 = disp.mouse_x; y1 = disp.mouse_y;
        curve.draw_line(x0,y0,x1,y1,col2).display(disp);
        x0 = x1; y0 = y1;
      }
    }
    disp.wait();
    if (disp.is_resized) disp.resize(disp);
  }
  curve.draw_line(x1,y1,xo,yo,col2).channel(0).draw_fill(0,0,col3);
  CImg<> img = CImg<>(curve.get_shared_channel(0)).normalize(-1,1);

  // Perform the "Mean Curvature Flow"
  img.distance_hamilton(10);
  CImg_3x3(I,float);
  for (unsigned int iter=0; iter<nb_iter && !disp.is_closed && !disp.is_keyQ; iter++) {
    CImg<> veloc(img.dimx(),img.dimy(),img.dimz(),img.dimv());
    cimg_for3x3(img,x,y,0,0,I) {
      const float
        ix = 0.5f*(Inc-Ipc),
        iy = 0.5f*(Icn-Icp),
        ixx = Inc+Ipc-2*Icc,
        iyy = Icn+Icp-2*Icc,
        ixy = 0.25f*(Ipp+Inn-Inp-Ipn),
        ngrad = ix*ix+iy*iy,
        iee = (ngrad>1e-5)?(( iy*iy*ixx - 2*ix*iy*ixy + ix*ix*iyy )/ngrad):0;
      veloc(x,y) = iee;
    }
    float m, M = veloc.maxmin(m);
    const double xdt = dt/cimg::max(cimg::abs(m),cimg::abs(M));
    img+=xdt*veloc;
    if (!(iter%10)) {
      get_level0(img).resize(disp.dimx(),disp.dimy()).draw_grid(20,20,0,0,false,false,col3,0.4f,0xCCCCCCCC,0xCCCCCCCC).
        draw_text(5,5,"Iteration %d",col3,0,1,11,iter).display(disp);
    }
    if (!(iter%30)) img.distance_hamilton(1,3);
    if (disp.is_resized) disp.resize();
  }

  // End of program
  return 0;
}