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,,CV_PI/,);
     //依次在图中绘制出每条线段
     for (size_t i = ;i < lines.size();i++)
     {
         float rho = lines[i][],theta = lines[i][];
         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+*(-b));//1000是取两点之间的距离，可操控量;
         pt1.y = cvRound(y0+*(a));//pt1是位于A较上的一个点;
         pt2.x = cvRound(x0-*(-b));//pt2是位于A较下的一个点;
         pt2.y = cvRound(y0-*(a));

         line(dstImage,pt1,pt2,Scalar(,,),,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=, double stn= );

 //! 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=, double maxLineGap= );

 //! 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=, double param2=,
                                int minRadius=, int maxRadius= );

//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());