contrast_preserve.cpp

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#include "precomp.hpp"
#include "opencv2/photo.hpp"
#include <cmath>
#include <vector>
#include <limits>
#include "contrast_preserve.hpp"

using namespace std;
using namespace cv;

void cv::decolor(InputArray _src, OutputArray _dst, OutputArray _color_boost)
{
    CV_INSTRUMENT_REGION();

    Mat I = _src.getMat();
    _dst.create(I.size(), CV_8UC1);
    Mat dst = _dst.getMat();

    _color_boost.create(I.size(), CV_8UC3);
    Mat color_boost = _color_boost.getMat();

    CV_Assert(!I.empty() && (I.channels()==3));

    // Parameter Setting
    const int maxIter = 15;
    const double tol = .0001;
    int iterCount = 0;
    double E = 0;
    double pre_E = std::numeric_limits<double>::infinity();

    Mat img;
    I.convertTo(img, CV_32FC3, 1.0/255.0);

    // Initialization
    Decolor obj;

    vector <double> Cg;
    vector < vector <double> > polyGrad;
    vector <Vec3i> comb;
    vector <double> alf;

    obj.grad_system(img,polyGrad,Cg,comb);
    obj.weak_order(img,alf);

    // Solver
    Mat Mt = Mat(int(polyGrad.size()),int(polyGrad[0].size()), CV_32FC1);
    obj.wei_update_matrix(polyGrad,Cg,Mt);

    vector <double> wei;
    obj.wei_inti(comb,wei);

    //////////////////////////////// main loop starting ////////////////////////////////////////

    vector <double> G_pos(alf.size());
    vector <double> G_neg(alf.size());
    vector <double> EXPsum(G_pos.size());
    vector <double> EXPterm(G_pos.size());
    vector <double> temp(polyGrad[0].size());
    vector <double> temp1(polyGrad[0].size());
    vector <double> temp2(EXPsum.size());
    vector <double> wei1(polyGrad.size());

    while(sqrt(pow(E-pre_E,2)) > tol)
    {
        iterCount +=1;
        pre_E = E;

        for(size_t i=0; i<polyGrad[0].size(); i++)
        {
            double val = 0.0;
            for(size_t j=0; j<polyGrad.size(); j++)
                val = val + (polyGrad[j][i] * wei[j]);
            temp[i] = val - Cg[i];
            temp1[i] = val + Cg[i];
        }

        for(size_t i=0; i<alf.size(); i++)
        {
            const double sqSigma = obj.sigma * obj.sigma;
            const double pos = ((1 + alf[i])/2) * exp(-1.0 * 0.5 * (temp[i] * temp[i]) / sqSigma);
            const double neg = ((1 - alf[i])/2) * exp(-1.0 * 0.5 * (temp1[i] * temp1[i]) / sqSigma);
            G_pos[i] = pos;
            G_neg[i] = neg;
        }

        for(size_t i=0; i<G_pos.size(); i++)
            EXPsum[i] = G_pos[i]+G_neg[i];

        for(size_t i=0; i<EXPsum.size(); i++)
            temp2[i] = (EXPsum[i] == 0) ? 1.0 : 0.0;

        for(size_t i=0; i<G_pos.size(); i++)
            EXPterm[i] = (G_pos[i] - G_neg[i])/(EXPsum[i] + temp2[i]);

        for(int i=0; i<int(polyGrad.size()); i++)
        {
            double val1 = 0.0;
            for(int j=0; j<int(polyGrad[0].size()); j++)
            {
                val1 = val1 + (Mt.at<float>(i,j) * EXPterm[j]);
            }
            wei1[i] = val1;
        }

        for(size_t i=0; i<wei.size(); i++)
            wei[i] = wei1[i];

        E = obj.energyCalcu(Cg, polyGrad, wei);

        if(iterCount > maxIter)
            break;
    }

    Mat Gray = Mat::zeros(img.size(),CV_32FC1);
    obj.grayImContruct(wei, img, Gray);

    Gray.convertTo(dst,CV_8UC1,255);

    ///////////////////////////////////       Contrast Boosting   /////////////////////////////////

    Mat lab;
    cvtColor(I,lab,COLOR_BGR2Lab);

    vector <Mat> lab_channel;
    split(lab,lab_channel);

    dst.copyTo(lab_channel[0]);

    merge(lab_channel,lab);

    cvtColor(lab,color_boost,COLOR_Lab2BGR);
}