OpenCV學習(九)之Mat的基本操作_1

實驗環境：VS2010 + OpenCV2.4.9.0

參考手冊：The OpenCV Tutorials, Release 2.4.9.0

Mat：OpenCV中圖像的基本容器，自OpenCV2.0之後的新功能，正在逐漸代替IplImage和CvMat。相比於IplImage和CvMat，Mat型側重於計算，數學性較高，OpenCV對Mat類型的計算也進行了優化。而CvMat和IplImage類型更側重於“圖像”，OpenCV對其中的圖像操作（縮放、單通道提取、圖像閾值操作等）進行了優化。在OpenCV2.0之前，OpenCV是完全用C實現的，但是，IplImage類型與CvMat類型的關係類似於面向對象中的繼承關係。實際上，CvMat之上還有一個更抽象的基類----CvArr，這在源代碼中會常見。根據參考手冊看來，Mat類表示一個 n 維的密集數值單通道或多通道數組。它可以用於存儲實數或複數值的向量和矩陣、灰度或彩色圖像、體素、向量場、點雲、張量、直方圖 （儘管較高維的直方圖存儲在SparseMat可能更好）。大概介紹至此，下面學習一些最基本用法：都以main函數的形式列出，頭文件略。

1、Mat矩陣的建立

int main(int argc,char** argv)
{
	Mat M(2,2,CV_8UC3,Scalar(0,0,255));
	//Mat M;
	//M.create(4,4,CV_8UC2);
	cout << "M = " << endl <<" " << M << endl << endl;
	system("pause");
	return 0;
}

2、幾類基本矩陣的創建

//Define some matrices
int main(int argc,char** argv)
{
	Mat E = Mat::eye(4,4,CV_64F);
	cout << "E = " << endl <<" " << E<< endl << endl;

	Mat ON  = Mat::ones(4,4,CV_32F);
	cout << "ON = " << endl <<" " << ON << endl << endl;

	Mat Z = Mat::zeros(3,3,CV_8UC1);
	cout << "Z = " << endl << " " << Z << endl << endl;
	system("pause");
	return 0;
}

3、小矩陣的創建和矩陣的複製/克隆

//For small matrices,may use comma separated initializers
int main(int argc,char** argv)
{
	Mat C = (Mat_<double>(3,3)<<0,-1,0,-1,5,-1,0,-1,0);
	cout << "C = " << endl <<" " << C<< endl << endl;

	//Create a new header for an existing Mat object and clone() or copyTo() it
	Mat rowClone = C.row(1).clone();
	cout << "rowClone = " << endl <<" " << rowClone << endl << endl;

	Mat rowCopy;
	C.row(1).copyTo(rowCopy);
	cout << "rowCopy = " << endl <<" " << rowCopy << endl << endl;
	
	system("pause");
	return 0;
}

4、用隨機函數生成矩陣的值，需要設置矩陣的最大最小值

//random function
int main(int argc,char** argv)
{
	Mat R = Mat(3,2,CV_8UC3);
	randu(R,Scalar::all(0),Scalar::all(255));
	cout << "R = " << endl <<" " << R << endl << endl;
	system("pause");
	return 0;
}

5、C++容器和Mat

int main(int argc,char** argv)
{
	//2D Point
	Point2f P(5,1);
	cout << "Point (2D) = " << P << endl << endl;

	//3D Point
	Point3f P3f(2,6,7);
	cout << "Point (3D) = " << P3f << endl << endl;

	//std::vector via cv::Mat
	vector<float> v;
	v.push_back((float)CV_PI);
	v.push_back(2);
	v.push_back(3.01f);
	cout << "Vector of float via Mat = " << Mat(v) << endl << endl;

	//std::vector of points
	vector<Point2f> vPoints(20);
	for(size_t i = 0;i < vPoints.size();i++)
		vPoints[i] = Point2f((float)(i*5),(float)(i % 7));
	cout << "A vector of 2D Points = " << vPoints << endl << endl;
	system("pause");
	return 0;
}