include/opencv2/video/background_segm.hpp

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#ifndef __OPENCV_BACKGROUND_SEGM_HPP__
#define __OPENCV_BACKGROUND_SEGM_HPP__

#include "opencv2/core/core.hpp"
#include <list>
namespace cv
{

class CV_EXPORTS_W BackgroundSubtractor : public Algorithm
{
public:
    virtual ~BackgroundSubtractor();
    CV_WRAP_AS(apply) virtual void operator()(InputArray image, OutputArray fgmask,
                                              double learningRate=0);

    virtual void getBackgroundImage(OutputArray backgroundImage) const;
};


class CV_EXPORTS_W BackgroundSubtractorMOG : public BackgroundSubtractor
{
public:
    CV_WRAP BackgroundSubtractorMOG();
    CV_WRAP BackgroundSubtractorMOG(int history, int nmixtures, double backgroundRatio, double noiseSigma=0);
    virtual ~BackgroundSubtractorMOG();
    virtual void operator()(InputArray image, OutputArray fgmask, double learningRate=0);

    virtual void initialize(Size frameSize, int frameType);

    virtual AlgorithmInfo* info() const;

protected:
    Size frameSize;
    int frameType;
    Mat bgmodel;
    int nframes;
    int history;
    int nmixtures;
    double varThreshold;
    double backgroundRatio;
    double noiseSigma;
};


class CV_EXPORTS BackgroundSubtractorMOG2 : public BackgroundSubtractor
{
public:
    BackgroundSubtractorMOG2();
    BackgroundSubtractorMOG2(int history,  float varThreshold, bool bShadowDetection=true);
    virtual ~BackgroundSubtractorMOG2();
    virtual void operator()(InputArray image, OutputArray fgmask, double learningRate=-1);

    virtual void getBackgroundImage(OutputArray backgroundImage) const;

    virtual void initialize(Size frameSize, int frameType);

    virtual AlgorithmInfo* info() const;

protected:
    Size frameSize;
    int frameType;
    Mat bgmodel;
    Mat bgmodelUsedModes;//keep track of number of modes per pixel
    int nframes;
    int history;
    int nmixtures;
    double varThreshold;
    // threshold on the squared Mahalanobis distance to decide if it is well described
    // by the background model or not. Related to Cthr from the paper.
    // This does not influence the update of the background. A typical value could be 4 sigma
    // and that is varThreshold=4*4=16; Corresponds to Tb in the paper.

    // less important parameters - things you might change but be carefull
    float backgroundRatio;
    // corresponds to fTB=1-cf from the paper
    // TB - threshold when the component becomes significant enough to be included into
    // the background model. It is the TB=1-cf from the paper. So I use cf=0.1 => TB=0.
    // For alpha=0.001 it means that the mode should exist for approximately 105 frames before
    // it is considered foreground
    // float noiseSigma;
    float varThresholdGen;
    //correspondts to Tg - threshold on the squared Mahalan. dist. to decide
    //when a sample is close to the existing components. If it is not close
    //to any a new component will be generated. I use 3 sigma => Tg=3*3=9.
    //Smaller Tg leads to more generated components and higher Tg might make
    //lead to small number of components but they can grow too large
    float fVarInit;
    float fVarMin;
    float fVarMax;
    //initial variance  for the newly generated components.
    //It will will influence the speed of adaptation. A good guess should be made.
    //A simple way is to estimate the typical standard deviation from the images.
    //I used here 10 as a reasonable value
    // min and max can be used to further control the variance
    float fCT;//CT - complexity reduction prior
    //this is related to the number of samples needed to accept that a component
    //actually exists. We use CT=0.05 of all the samples. By setting CT=0 you get
    //the standard Stauffer&Grimson algorithm (maybe not exact but very similar)

    //shadow detection parameters
    bool bShadowDetection;//default 1 - do shadow detection
    unsigned char nShadowDetection;//do shadow detection - insert this value as the detection result - 127 default value
    float fTau;
    // Tau - shadow threshold. The shadow is detected if the pixel is darker
    //version of the background. Tau is a threshold on how much darker the shadow can be.
    //Tau= 0.5 means that if pixel is more than 2 times darker then it is not shadow
    //See: Prati,Mikic,Trivedi,Cucchiarra,"Detecting Moving Shadows...",IEEE PAMI,2003.
};

class CV_EXPORTS BackgroundSubtractorGMG: public cv::BackgroundSubtractor
{
public:
    BackgroundSubtractorGMG();
    virtual ~BackgroundSubtractorGMG();
    virtual AlgorithmInfo* info() const;

    void initialize(cv::Size frameSize, double min, double max);

    virtual void operator()(InputArray image, OutputArray fgmask, double learningRate=-1.0);

    void release();

    int     maxFeatures;
    double  learningRate;
    int     numInitializationFrames;
    int     quantizationLevels;
    double  backgroundPrior;
    double  decisionThreshold;
    int     smoothingRadius;
    bool updateBackgroundModel;

private:
    double maxVal_;
    double minVal_;

    cv::Size frameSize_;
    int frameNum_;

    cv::Mat_<int> nfeatures_;
    cv::Mat_<unsigned int> colors_;
    cv::Mat_<float> weights_;

    cv::Mat buf_;
};

}

#endif