OpenCV图像处理中常用函数汇总（2）

// 霍夫线变换 hough
    vector<Vec2f> lines;//定义一个矢量结构lines用于存放得到的线段矢量集合
    HoughLines(dstImage,lines,1,CV_PI/180,150);
    //依次在图中绘制出每条线段
    for (size_t i = 0;i < lines.size();i++)
    {
        float rho = lines[i][0],theta = lines[i][1];
        Point pt1,pt2;
        double a = cos(theta),b = sin(theta);
        double x0 = rho*a,y0 = rho*b;//A是与直线垂直的线交点 坐标为(x0,y0)=(rho*cos(theta),rho*sin(theta));
        //向上取整函数cvCeil、向下取整函数cvFloor、四舍五入函数cvRound;

        pt1.x = cvRound(x0+1000*(-b));//1000是取两点之间的距离，可操控量;
        pt1.y = cvRound(y0+1000*(a));//pt1是位于A较上的一个点;
        pt2.x = cvRound(x0-1000*(-b));//pt2是位于A较下的一个点;
        pt2.y = cvRound(y0-1000*(a));

        line(dstImage,pt1,pt2,Scalar(55,100,195),1,CV_AA);
    }
    imshow("hough检测直线图",dstImage);
    //waitKey(0);

 //霍夫变换线、圆
 1 //! finds lines in the black-n-white image using the standard or pyramid Hough transform
CV_EXPORTS_W void HoughLines( InputArray image, OutputArray lines,
                              double rho, double theta, int threshold,
                              double srn=0, double stn=0 );

//! finds line segments in the black-n-white image using probabalistic Hough transform
CV_EXPORTS_W void HoughLinesP( InputArray image, OutputArray lines,
                               double rho, double theta, int threshold,
                               double minLineLength=0, double maxLineGap=0 );

//! finds circles in the grayscale image using 2+1 gradient Hough transform
CV_EXPORTS_W void HoughCircles( InputArray image, OutputArray circles,
                               int method, double dp, double minDist,
                               double param1=100, double param2=100,
                               int minRadius=0, int maxRadius=0 );

//扩充边界函数
//! copies 2D array to a larger destination array with extrapolation of the outer part of src using the specified border mode
CV_EXPORTS_W void copyMakeBorder( InputArray src, OutputArray dst,
                                int top, int bottom, int left, int right,
                                int borderType, const Scalar& value=Scalar() );

 // 计算非0个数  平均数 标准差
 1 //! computes the number of nonzero array elements
CV_EXPORTS_W int countNonZero( InputArray src );
//! returns the list of locations of non-zero pixels
CV_EXPORTS_W void findNonZero( InputArray src, OutputArray idx );

//! computes mean value of selected array elements
CV_EXPORTS_W Scalar mean(InputArray src, InputArray mask=noArray());
//! computes mean value and standard deviation of all or selected array elements
CV_EXPORTS_W void meanStdDev(InputArray src, OutputArray mean, OutputArray stddev,
                             InputArray mask=noArray());