opencv学习之路Mat类介绍，基本绘图函数

Posted 2020-09-28 进击的小猴子

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 }