OpenCV基础篇之Mat数据结构
程序及分析
/*
* FileName : MatObj.cpp
* Author : xiahouzuoxin @163.com
* Version : v1.0
* Date : Thu 15 May 2014 09:12:45 PM CST
* Brief :
*
* Copyright (C) MICL,USTB
*/
#include <cv.h>
#include <highgui.h>
#include <iostream>
using namespace std;
using namespace cv;
int main(void)
{
/*
* Create Mat
*/
Mat M(2,2,CV_8UC3, Scalar(0,0,255));
cout << "M=" << endl << " " << M << endl << endl;
/*
* Matlab style
*/
Mat E = Mat::eye(4,4,CV_64F);
cout << "E=" << endl << " " << E << endl << endl;
E = Mat::ones(4,4,CV_64F);
cout << "E=" << endl << " " << E << endl << endl;
E = Mat::zeros(4,4,CV_64F);
cout << "E=" << endl << " " << E << endl << endl;
/*
* Convert IplImage to Mat
*/
IplImage *img = cvLoadImage("../test_imgs/Lena.jpg");
Mat L(img);
namedWindow("Lena.jpg", CV_WINDOW_AUTOSIZE);
imshow("Lena.jpg", L);
waitKey(0);
/*
* Init Mat with separated data
*/
Mat C = (Mat_<int>(3,3) << 0,1,2,3,4,5,6,7,8);
cout << "C=" << endl << " " << C << endl << endl;
return 0;
}
1.
Mat是OpenCV最基本的数据结构，Mat即矩阵（Matrix）的缩写，Mat数据结构主要包含2部分：Header和Pointer。Header中主要包含矩阵的大小，存储方式，存储地址等信息；Pointer中存储指向像素值的指针。我们在读取图片的时候就是将图片定义为Mat类型，其重载的构造函数一大堆，
class CV_EXPORTS Mat
{
public:
//! default constructor
Mat();
//! constructs 2D matrix of the specified size and type
// (_type is CV_8UC1, CV_64FC3, CV_32SC(12) etc.)
Mat(int _rows, int _cols, int _type);
Mat(Size _size, int _type);
//! constucts 2D matrix and fills it with the specified value _s.
Mat(int _rows, int _cols, int _type, const Scalar& _s);
Mat(Size _size, int _type, const Scalar& _s);
//! constructs n-dimensional matrix
Mat(int _ndims, const int* _sizes, int _type);
Mat(int _ndims, const int* _sizes, int _type, const Scalar& _s);
//! copy constructor
Mat(const Mat& m);
//! constructor for matrix headers pointing to user-allocated data
Mat(int _rows, int _cols, int _type, void* _data, size_t _step=AUTO_STEP);
Mat(Size _size, int _type, void* _data, size_t _step=AUTO_STEP);
Mat(int _ndims, const int* _sizes, int _type, void* _data, const size_t* _steps=0);
//! creates a matrix header for a part of the bigger matrix
Mat(const Mat& m, const Range& rowRange, const Range& colRange=Range::all());
Mat(const Mat& m, const Rect& roi);
Mat(const Mat& m, const Range* ranges);
//! converts old-style CvMat to the new matrix; the data is not copied by default
Mat(const CvMat* m, bool copyData=false);
//! converts old-style CvMatND to the new matrix; the data is not copied by default
Mat(const CvMatND* m, bool copyData=false);
//! converts old-style IplImage to the new matrix; the data is not copied by default
Mat(const IplImage* img, bool copyData=false);
......
}
要了解如何初始化Mat结构，就应该了解它的构造函数，比如程序中的第一初始化方式调用额就是
Mat(int _rows, int _cols, int _type, const Scalar& _s);
这个构造函数。
IplImage*是C语言操作OpenCV的数据结构，在当时C操纵OpenCV的时候，地位等同于Mat，OpenCV为其提供了一个接口，很方便的直接将IplImage转化为Mat，即使用构造函数
Mat(const IplImage* img, bool copyData=false);
上面程序中的第二种方法就是使用的这个构造函数。
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