OpenCV基本图像容器Mat的几种创建方法

參考文章：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版本号后出现的Mat矩形类，主要是參考opencv自带doc目录下的tutiol教材。通过这次实验认为用Mat的话以下几点须要特别注意（在代码中能够体现出来）：

1. 利用create函数又一次改变Mat数据在内存中的布局。

2. 注意多通道数据在Mat中事实上也是占一个元素的位置的。 

3. 学会多维Mat的创建方法。

4. 当Mat矩阵比較小时。学会直接赋值的方法，即用Mat_。

5. 掌握Mat矩阵内容输出到终端时的几种常见格式。

6. 注意假设vector是单独一维的话须要转换成Mat才干输出。多维的能够直接输出，比如vector里面存放的是点的话。

#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

using namespace std;
using namespace cv;

int demo_Mat()
{
    int next_num = 1;
	char tmp;
	while(next_num<7)
	{
		cout<<"-------- "<<next_num<<" --------"<<endl;
		waitKey(0);

		switch (next_num)
        {
           case 1:
            {
				Mat M( 2, 2, CV_8UC3, Scalar(0,255,0) );//事实上是2*6的矩阵，由于每一个元素有3个通道。

cout<<"create by using the constructor..."<<endl;
				cout<<"M = \n "<<M<<endl;

				M.create( 4, 4, CV_8UC(2));//括号中面的2表示2通道
				cout<< "create by using create function..."<<endl;
				cout<<"M = \n "<<M<<endl;
				break;
            }//当case语句里面变量定义时，须要用括号括起来，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 =   "<<L<<endl;此处不能打印出来，由于那仅仅适应二维数组
                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 "<<E<<endl;
                cout<<"O = \n "<<O<<endl;
                cout<<"Z = \n "<<Z<<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 "<<C<<endl;
				cout<<"row_clone =  "<<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) =  "<<R<<endl;
                cout<< "demonstrate the output formating options..."<<endl;
                cout<<"R (python) = \n "<<format(R, "python")<<endl;
                cout<<"R (numpy) = \n "<<format(R, "numpy")<<endl;//numpy是一个用python实现的科学计算包
                cout<<"R (csv) = \n "<<format(R, "csv")<<endl;//csv,逗号分隔符
                cout<<"R (c) = \n " <<format(R, "C")<<endl;
                break;
            }
			case 6:
			{
				cout<< "the point format output..."<<endl;

				Point2f P1(5, 1);
				cout<<"Point (2D) = "<<P1<<endl;

				Point3f P2(4, 5, 6);
				cout<<"Point (3D) = "<<P2<<endl;

				vector<float>v;
				v.push_back( (float)CV_PI);
				v.push_back( 2 );//push_back为在其尾部增加一个数据
				v.push_back( 3.01f );
				cout<<"vector of float: = "<<Mat(v)<<endl;//vector数据是没法单独输出的,因此能够借助mat输出

				int N = 20;
				vector<Point2f>vPoints(N);//vector能够用变量定义其长度。比数组好用
				for( size_t E = 0; E < vPoints.size(); ++E )    //size_t事实上就是一个unsigned int类型
					vPoints[E] = Point2f((float)(E*5), (float)(E%7));
				cout<<"vPoints[] = \n"<<vPoints<<endl;//可是vector点确实能够直接输出的。由于这时候的vector本身就是
														//一个多维（至少2维）Mat了
				break;
			}
			default:
				break;
        }
		next_num++;
	}
	return 0;
}

执行结果：