opencvmeanstddev计算矩阵的均值和标准偏差

#include<opencv2/opencv.hpp>
#include<iostream>
#include  <vector>


int main(int argc, char** argv) {

    cv::Mat src(5, 4, CV_8UC3, cv::Scalar(10,20,30));
    std::cerr << src << std::endl;

    cv::Mat mean, stddev;
    cv::meanStdDev(src,mean, stddev);
    double m = 0, sd = 0;
    std::cerr << mean << std::endl;

    m = mean.at<double>(0, 0);//返回第一通道均值
    std::cerr << "第一通道均值=" <<m<< std::endl;

    m = mean.at<double>(1, 0);//返回第二通道均值
    std::cerr << "第二通道均值=" << m << std::endl;

    m = mean.at<double>(2, 0);//返回第三通道均值
    std::cerr << "第三通道均值=" << m << std::endl;

    std::cerr << stddev << std::endl;

    sd = stddev.at<double>(0, 0); //返回第一通道标准偏差
    std::cerr << "第一通道标准偏差=" << sd << std::endl;

    sd = stddev.at<double>(1, 0); //返回第二通道标准偏差
    std::cerr << "第二通道标准偏差=" << sd << std::endl;

    sd = stddev.at<double>(2, 0); //返回第三通道标准偏差
    std::cerr << "第三通道标准偏差=" << sd << std::endl;
    
    cv::waitKey(0);
    return 0;
}