opencv学习之路（4）、Mat类介绍，基本绘图函数
一、Mat类创建
Mat img;//创建无初始化矩阵 Mat img1(200,100,CV_8UC1);//200行，100列（长200，宽100） Mat img2(Size(200,100),CV_8UC3,Scalar(0,255,0));//长100，宽200 Mat img3(200,100,CV_8UC3,Scalar(0,255,0));//创建200行，100列的8位三通道矩阵 Mat img4(200,100,CV_8UC1,Scalar(255));//创建单通道矩阵
1 #include <opencv2/opencv.hpp> 2 using namespace cv; 3 4 void main(){ 5 Mat img1=imread("E://1.jpg"); 6 Mat img2(img1); 7 Mat img3=img1; 8 Mat img4=img1.clone(); 9 Mat img5; 10 img1.copyTo(img5); 11 12 cvtColor(img1,img1,CV_BGR2HSV);//BGR图转为HSV图 13 imshow("img1",img1); 14 imshow("img2",img2); 15 imshow("img3",img3);//image1/2/3跟随原图变化 16 imshow("img4",img4); 17 imshow("img5",img5);//image4/5不会跟随原图变化 18 waitKey(0); 19 }
二、基本绘图函数
1、画线、画圆、画矩形
1 #include <opencv2/opencv.hpp> 2 using namespace cv; 3 4 void main(){ 5 Mat img(500,400,CV_8UC3,Scalar(255,255,255));//创建一个500行400列，3通道（即彩色图）的白色图 6 line(img,Point(10,10),Point(100,250),Scalar(0,255,255),20,8);//在img图中画一条黄线，线宽为20，线型为8联通（一般都设置为8） 7 circle(img,Point(200,100),50,Scalar(0,255,255),15,8); //以（200,100）为圆心，半径为50，线宽为15画空心圆 8 circle(img,Point(200,250),50,Scalar(0,255,255),-1,8); //设置为-1时，画实心圆 9 rectangle(img,Point(10,100),Point(200,200),Scalar(0,0,255),1,8); //传入坐上、右下角坐标，画空心矩形 10 rectangle(img,Rect(200,300,100,50),Scalar(0,255,0),-1,8); //传矩形数据（左上角坐标（200,300）和宽100，高50），画实心绿色矩形 11 12 imshow("drawing",img); 13 waitKey(0); 14 }
2、画椭圆、画多边形、写入文字
1 #include <opencv2/opencv.hpp> 2 using namespace cv; 3 4 void main(){ 5 Mat img(600,650,CV_8UC3,Scalar(255,255,255)); 6 ellipse(img,Point(200,200),Size(180,80),15,0,360,Scalar(0,255,255),10,8); //画椭圆，（200,200）为中点，15旋转角度，0~360度，长轴180，短轴80 7 ellipse(img,RotatedRect(Point(350,350),Size(150,100),40),Scalar(0,255,0),-1,8); //画椭圆，40旋转角度 8 9 Point ppt[]={Point(120,50),Point(180,50),Point(210,100),Point(180,150),Point(120,150),Point(90,100)}; 10 Point ppt2[]={Point(80,400),Point(80,550),Point(250,500),Point(300,550)};//定义点集 11 const Point* pts[]={ppt}; 12 const Point* pts2[]={ppt2}; 13 int npt[]={6}; 14 int npt2[]={4}; 15 fillPoly(img,pts,npt,1,Scalar(255,255,0),8); //画填充多边形 16 polylines(img,pts2,npt2,1,false,Scalar(0,100,200),2,8); //画多边形，false为不闭合，true为闭合 17 18 putText(img,"China",Point(400,400),CV_FONT_BLACK,2,Scalar(100,100,100),5,8);//写入文字 19 20 imshow("drawing",img); 21 waitKey(0); 22 }
