opencv Mat的几种初始化方式

转载于：https://blog.csdn.net/jeakon/article/details/41942197

参考文章：http://www.cnblogs.com/tornadomeet/archive/2012/07/19/2599376.html

实验说明： （引用）

　　本文主要讲一些opencv 2.0版本后出现的Mat矩形类，主要是参考opencv自带doc文件夹下的tutiol教材。通过这次实验觉得用Mat的话下面几点需要特别注意（在代码中可以体现出来）：

#include 
#include 
#include 
#include 
 
using namespace std;
using namespace cv;
 
int demo_Mat()
{
    int next_num = 1;
 char tmp;
 while(next_num<7)
{
       cout<<"-------- "<" --------"<<endl;
waitKey(0);
        
        switch (next_num)
{
           case 1:
{
              Mat M( 2, 2, CV_8UC3, Scalar(0,255,0) );//其实是2*6的矩阵，因为每个元素有3个通道。
             cout<<"create by using the constructor..."<<endl;
                cout<<"M = \n "<endl;
 
M.create( 4, 4, CV_8UC(2));//括号里面的2表示2通道
               cout<< "create by using create function..."<<endl;
               cout<<"M = \n "<endl;
              break;
}//当case语句里面变量定义时，需要用括号括起来，否则会报错
           case 2:
{
                int sz[3] = {2, 2, 2};
                Mat L( 3, sz, CV_8UC(1), Scalar::all(0) );
                cout<< "create multidimensional matrix..."<<endl;
                // cout<<"L =   "<
                break;
}
            case 3:
{
Mat E = Mat::eye(4, 4, CV_64F);
Mat O = Mat::ones(2, 3, CV_32F);
Mat Z = Mat::zeros(3, 3, CV_8UC1);
                cout<< "using matlab stytle..."<<endl;
                cout<<"E = \n "<endl;
                cout<<"O = \n "<endl;
                cout<<"Z = \n "<endl;
                break;
}
         case 4:
{
Mat C =(Mat_<double>(3,3)<<0,-1,0,-1,5,-1,0,-1,0);//直接赋初始值的方法
Mat row_clone = C.row(1).clone();
              cout<< "create 3*3 double-precision identity matrix..."<<endl;
               cout<<"C = \n "<endl;
              cout<<"row_clone =  "<endl;
                break;
}
            case 5:
{
Mat R = Mat( 3, 2, CV_8UC3 );
randu( R, Scalar::all(0), Scalar::all(255) );
                cout<< "fill a matrix with rand numbers..."<<endl;
                cout<<"R (default) =  "<endl;
                cout<< "demonstrate the output formating options..."<<endl;
                cout<<"R (python) = \n "<"python")<<endl;
                cout<<"R (numpy) = \n "<"numpy")<<endl;//numpy是一个用python实现的科学计算包
                cout<<"R (csv) = \n "<"csv")<<endl;//csv,逗号分隔符
                cout<<"R (c) = \n " <"C")<<endl;
                break;
}
         case 6:
{
               cout<< "the point format output..."<<endl;
 
              Point2f P1(5, 1);
             cout<<"Point (2D) = "<endl;
 
              Point3f P2(4, 5, 6);
             cout<<"Point (3D) = "<endl;
 
              vector<float>v;
v.push_back( (float)CV_PI);
v.push_back( 2 );//push_back为在其尾部加入一个数据
v.push_back( 3.01f );
              cout<<"vector of float: = "<endl;//vector数据是没法单独输出的,因此可以借助mat输出
 
                int N = 20;
              vectorvPoints(N);//vector可以用变量定义其长度，比数组好用
               for( size_t E = 0; E < vPoints.size(); ++E )    //size_t其实就是一个unsigned int类型
vPoints[E] = Point2f((float)(E*5), (float)(E%7));
             cout<<"vPoints[] = \n"<endl;//但是vector点确实可以直接输出的，因为这时候的vector本身就是
                                                      //一个多维（至少2维）Mat了
              break;
}
           default:
              break;
}
next_num++;
}
  return 0;
}
 

运行结果：

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