opencv學習之路（4）、Mat類介紹，基本繪圖函數

一、Mat類創建

    Mat img;//創建無初始化矩陣
    Mat img1(200,100,CV_8UC1);//200行，100列（長200，寬100）
    Mat img2(Size(200,100),CV_8UC3,Scalar(0,255,0));//長100，寬200
    Mat img3(200,100,CV_8UC3,Scalar(0,255,0));//創建200行，100列的8位三通道矩陣
    Mat img4(200,100,CV_8UC1,Scalar(255));//創建單通道矩陣    

#include <opencv2/opencv.hpp>
using namespace cv;

void main(){
    Mat img1=imread("E://1.jpg");
    Mat img2(img1);
    Mat img3=img1;
    Mat img4=img1.clone();
    Mat img5;
    img1.copyTo(img5);

    cvtColor(img1,img1,CV_BGR2HSV);//BGR圖轉為HSV圖
    imshow("img1",img1);
    imshow("img2",img2);
    imshow("img3",img3);//image1/2/3跟隨原圖變化
    imshow("img4",img4);
    imshow("img5",img5);//image4/5不會跟隨原圖變化
    waitKey(0);
}

二、基本繪圖函數

1、畫線、畫圓、畫矩形

#include <opencv2/opencv.hpp>
using namespace cv;

void main(){
    Mat img(500,400,CV_8UC3,Scalar(255,255,255));//創建一個500行400列，3通道（即彩色圖）的白色圖
    line(img,Point(10,10),Point(100,250),Scalar(0,255,255),20,8);//在img圖中畫一條黃線，線寬為20，線型為8聯通（一般都設置為8）
    circle(img,Point(200,100),50,Scalar(0,255,255),15,8);   //以（200,100）為圓心，半徑為50，線寬為15畫空心圓
    circle(img,Point(200,250),50,Scalar(0,255,255),-1,8);   //設置為-1時，畫實心圓
    rectangle(img,Point(10,100),Point(200,200),Scalar(0,0,255),1,8);   //傳入坐上、右下角坐標，畫空心矩形
    rectangle(img,Rect(200,300,100,50),Scalar(0,255,0),-1,8); //傳矩形數據（左上角坐標（200,300）和寬100，高50），畫實心綠色矩形

    imshow("drawing",img);
    waitKey(0);
}

2、畫橢圓、畫多邊形、寫入文字

#include <opencv2/opencv.hpp>
using namespace cv;

void main(){
    Mat img(600,650,CV_8UC3,Scalar(255,255,255));
    ellipse(img,Point(200,200),Size(180,80),15,0,360,Scalar(0,255,255),10,8);   //畫橢圓，（200,200）為中點，15旋轉角度，0~360度，長軸180，短軸80
    ellipse(img,RotatedRect(Point(350,350),Size(150,100),40),Scalar(0,255,0),-1,8);   //畫橢圓，40旋轉角度
    
    Point ppt[]={Point(120,50),Point(180,50),Point(210,100),Point(180,150),Point(120,150),Point(90,100)};
    Point ppt2[]={Point(80,400),Point(80,550),Point(250,500),Point(300,550)};//定義點集
    const Point* pts[]={ppt};
    const Point* pts2[]={ppt2};
    int npt[]={6};
    int npt2[]={4};
    fillPoly(img,pts,npt,1,Scalar(255,255,0),8);   //畫填充多邊形
    polylines(img,pts2,npt2,1,false,Scalar(0,100,200),2,8);   //畫多邊形，false為不閉合，true為閉合
    
    putText(img,"China",Point(400,400),CV_FONT_BLACK,2,Scalar(100,100,100),5,8);//寫入文字

    imshow("drawing",img);
    waitKey(0);
}