imgproc模块--轮廓矩

1.目的
（1）使用openCV函数moments计算图像所有的矩
（2）使用openCV函数contoursArea计算轮廓面积
（3）使用openCV函数arcLength计算曲线或者轮廓长度

2.原理
[1]空间矩的计算

[2]中心矩的计算

其中：

[3]归一化的中心矩的计算

在openCV中
// 空间矩 double m00, m10, m01, m20, m11, m02, m30, m21, m12, m03;
// 中心矩 double mu20, mu11, mu02, mu30, mu21, mu12, mu03;
// 中心归一化矩 double nu20, nu11, nu02, nu30, nu21, nu12, nu03;

3.完整代码
（1）CommonInclude.h

#ifndef COMMON_INCLUDE#define COMMON_INCLUDE#include<iostream>#include<opencv2/core/core.hpp>#include<opencv2/highgui/highgui.hpp>#include<opencv2/imgproc/imgproc.hpp>using namespace std;using namespace cv;#endif

（2）ContoursMoment.cpp

#include "CommonInclude.h"Mat src; Mat src_gray;int thresh = 100;int max_thresh = 255;RNG rng(12345);/** @thresh_callback 函数 */void thresh_callback(int, void* ){    Mat canny_output;    vector<vector<Point> > contours;    vector<Vec4i> hierarchy;    /// 使用Canndy检测边缘    Canny( src_gray, canny_output, thresh, thresh*2, 3 );    /// 找到轮廓    findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );    /// 计算矩    vector<Moments> mu(contours.size() );    for( int i = 0; i < contours.size(); i++ )    {         mu[i] = moments( contours[i], false );    }    ///  计算质心:    vector<Point2f> mc( contours.size() );    for( int i = 0; i < contours.size(); i++ )    {        mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 );    }    /// 绘制轮廓    Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );    for( int i = 0; i< contours.size(); i++ )    {        Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );        drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );        circle( drawing, mc[i], 4, color, -1, 8, 0 );    }    /// 显示到窗口中    namedWindow( "Contours", CV_WINDOW_AUTOSIZE );    imshow( "Contours", drawing );    /// 通过m00计算轮廓面积并且和OpenCV函数比较    printf("\t Info: Area and Contour Length \n");    for( int i = 0; i< contours.size(); i++ )    {        printf(" * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n", i, mu[i].m00, contourArea(contours[i]), arcLength( contours[i], true ) );    }}/** @主函数 */int main( int argc, char** argv ){    /// 读入原图像, 返回3通道图像数据    src = imread( argv[1], 1 );    /// 把原图像转化成灰度图像并进行平滑    cvtColor( src, src_gray, CV_BGR2GRAY );    blur( src_gray, src_gray, Size(3,3) );    /// 创建新窗口    char* source_window = "Source";    namedWindow( source_window, CV_WINDOW_AUTOSIZE );    imshow( source_window, src );    createTrackbar( " Canny thresh:", "Source", &thresh, max_thresh, thresh_callback );    thresh_callback( 0, 0 );    waitKey(0);    return(0);}

参考文献
1.http://www.opencv.org.cn/opencvdoc/2.3.2/html/doc/tutorials/imgproc/shapedescriptors/moments/moments.html