7 访问多通道Mat对象中的值

7.1使用成员函数at()

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main()
{
    Mat mm = (Mat_<Vec3f>(2, 2) << Vec3f(1, 11, 21), Vec3f(2, 12, 32), Vec3f(3, 13, 23), Vec3f(4, 24, 34));
    cout << mm << endl;
    for (int r = 0; r < mm.rows; r++) {
        for (int c = 0; c < mm.cols; c++) {
            cout << mm.at<Vec3f>(r, c) << ",";
        }
        cout << endl;
    }
    return 0;
}

在这里插入图片描述

7.2使用成员函数ptr()

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main()
{
    Mat mm = (Mat_<Vec3f>(2, 2) << Vec3f(1, 11, 21), Vec3f(2, 12, 32), Vec3f(3, 13, 23), Vec3f(4, 24, 34));
    cout << mm << endl;
    for (int r = 0; r < mm.rows; r++) {
        //每行首元素的地址
        Vec3f* ptr = mm.ptr<Vec3f>(r);
        for (int c = 0; c < mm.cols; c++) {
            cout << ptr[c] << ",";
        }
        cout << endl;
    }
    return 0;
}

在这里插入图片描述

7.3使用成员函数isContinuous()和ptr()

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main()
{
    Mat mm = (Mat_<Vec3f>(2, 2) << Vec3f(1, 11, 21), Vec3f(2, 12, 32), Vec3f(3, 13, 23), Vec3f(4, 24, 34));
    cout << mm << endl;
   if(mm.isContinuous()){
       //指向多通道矩阵的第一个元素的指针
        Vec3f* ptr = mm.ptr<Vec3f>(0);
        for (int c = 0; c < mm.cols*mm.rows; c++) {
            cout << ptr[c] << endl;
        }
    }
    return 0;
}

在这里插入图片描述

7.4使用成员变量step和data

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main(){
    Mat mm = (Mat_<Vec3f>(2, 2) << Vec3f(1, 11, 21), Vec3f(2, 12, 32), Vec3f(3, 13, 23), Vec3f(4, 24, 34));
    cout << mm << endl;
  for(int r=0;r<mm.rows;r++){
      for(int c=0;c<mm.cols;c++){
            Vec3f* ptr = (Vec3f*)(mm.data + mm.step[0] * r + c * mm.step[1]);
            cout << *ptr << ",";
        }
        cout << endl;
    }
    return 0;
}

在这里插入图片描述

7.5分离通道split(mm,vec)

将所有向量第一个值组成的单通道矩阵作为第一通道，以此类推

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main(){
    Mat mm = (Mat_<Vec3f>(2, 2) << Vec3f(1, 11, 21), Vec3f(2, 12, 32), Vec3f(3, 13, 23), Vec3f(4, 24, 34));
    cout << mm << endl;
    vector<Mat> planes;
    split(mm, planes);
    cout << planes[0] << endl;//第一个通道
    cout << planes[1] << endl;//第二个通道
    cout << planes[2] << endl;//第三个通道
    
    return 0;
}

在这里插入图片描述

7.6合并通道merge( , , )

将单通道矩阵存储在Mat中：

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main(){
    Mat planes0 = (Mat_<int>(2, 2) << 1,2,3,4);
    Mat planes1 = (Mat_<int>(2, 2) << 5, 6, 7, 8);
    Mat planes2 = (Mat_<int>(2, 2) << 9, 10, 11, 12);
    Mat planes[] = { planes0 ,planes1 ,planes2 };
    Mat mat;
    merge(planes,3,mat);
    cout << mat << endl;
    return 0;
}

在这里插入图片描述

存储在vector容器中，使用merge重载函数：

#include <opencv2/core/core.hpp>  
#include<iostream>  
using namespace std;
using namespace cv;
int main(){
    Mat planes0 = (Mat_<int>(2, 2) << 1,2,3,4);
    Mat planes1 = (Mat_<int>(2, 2) << 5, 6, 7, 8);
    Mat planes2 = (Mat_<int>(2, 2) << 9, 10, 11, 12);
    vector<Mat> plane;
    plane.push_back(planes0);
    plane.push_back(planes1);
    plane.push_back(planes2);
    Mat mat;
    merge(plane, mat);
    cout << mat << endl;
    return 0;
}