In BackgroundSubtractorMOG2 set background fixed(static) like BackgroundSubtractorMOG

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Is there any way to fix the background set in BackgroundSubtractorMOG2 as in BackgroundSubtractorMOG.

heres my code to detect hand ... It does not have a fixed background

    #include<opencv2/opencv.hpp>
    #include<iostream>
    #include<vector> 
    using namespace cv; 
    using namespace std;

    const int nmixtures=10; 
    const bool shadow=false;  
    const int history =1000;

    BackgroundSubtractorMOG2 back_obj(history,nmixtures,shadow); 
    //BackgroundSubtractorMOG back_obj;  this gives me a first frame as fixed background. 
    int main(int argc,char **argv) { 

     Mat original; 
     Mat background,foreground; 
     VideoCapture cap(0); 
     std::vector<std::vector<cv::Point> >contours; 
     namedWindow("ORIGINAL"); 
     namedWindow("BACKGROUND"); 
     namedWindow("FOREGROUND"); 
     while(1)
     {
            cap>>original;  
            back_obj.operator()(original,foreground);
            back_obj.getBackgroundImage(background);    
            erode(foreground,foreground,Mat());         
            dilate(foreground,foreground,Mat());                         
            findContours(foreground,contours,CV_RETR_EXTERNAL,CV_CHAIN_APPROX_NONE);      
            drawContours(original,contours,-1,Scalar(255,255,0),4);     
            imshow("ORIGINAL",original);    
            imshow("BACKGROUND",background);
            imshow("FOREGROUND",foreground);    
            if(waitKey(10)>=0) 
            {
           break;
          }
     }
     return 0;
    }