Learning OpenCV 3 章节习题——第6章

目录

1.绘图练习

2.灰度练习

3.动态文字练习

4.编写绘图程序

5.计算直线的像素数

5.1 什么情况下4连通和8连通能得到相同的像素数？

5.2 哪一种连通方式有更多的像素数？

5.3 在4连通和8连通的两种情况下，对于一条给定的直线段，直线长度和使用迭代器计算出的像素数之间的区别是什么？哪一种连接更接近真实的直线长度？

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1 绘图练习

//1.绘图练习
	//1.1 绘制圆
	Mat drawMat1(300,300,CV_8UC3,Scalar(0));
	circle(drawMat1, Point(150, 150), 50, Scalar(255, 0, 255),
		2, //宽度为2个像素长度
		8, //轮廓连通方法 4连通或者8连通
		0 //圆心移位shift  tarVal=priVal/pow(2,shift) =75
		);
	circle(drawMat1, Point(150, 150), 50, Scalar(0, 0, 255),
		2, //宽度为2个像素长度
		8, //轮廓连通方法 4连通或者8连通
		1 //圆心移位shift  tarVal=priVal/pow(2,shift) =75
 		);

//1.2 判断直线与矩形的关系：只有当直线完全位于矩形之外才会返回 false
Mat drawMat2(300, 300, CV_8UC3, Scalar(0));
Rect rect(100,100,100,100);
rectangle(drawMat2,rect,Scalar(0,0,255),2,8);
if (clipLine(rect, Point(50, 50), Point(150, 150))) 
line(drawMat2, Point(50, 50), Point(150, 150), Scalar(255, 0, 255), 2, 8);

//1.3 绘制椭圆
	Mat drawMat3(300, 300, CV_8UC3, Scalar(0));
	RotatedRect rect1(Point(50, 50), Point(50, 200), Point(150, 200));
	ellipse(drawMat3,rect1,Scalar(255,0,255),2,8);
	ellipse(drawMat3,
		Point(200, 200),//中心点
		Size(50, 25),//长半轴50 短半轴25
		0,//长半轴夹角
		0,//起始角度
		360,//终止角度
		Scalar(0,0,255),
		2,
		8
		);

//1.4 基于角度对椭圆进行采样
	Mat drawMat4(300, 300, CV_8UC3, Scalar(0));
	vector<Point> result;
	//每隔 10°采样一次
	ellipse2Poly(Point(150,150),Size(70,50),0,0,360,10,result);
	for (Point m : result) circle(drawMat4,m,1,Scalar(0,0,255),-1);

//1.5 直线迭代器
	Mat drawMat5(300, 300, CV_8UC1, Scalar(0));
	LineIterator line(drawMat5,Point(100,100),Point(200,200),8,false);
	for (int i = 0; i < line.count; i++, line++)
		drawMat5.at<uchar>(line.pos().y, line.pos().x) = line.pos().y;

	//1.6 绘制文字
	Mat drawMat6(300, 300, CV_8UC1, Scalar(0));
	String text = "Hellow World !";
	// 左上角坐标(50,150) 手写体
	putText(drawMat6,text,Point(50,150),
		       FONT_HERSHEY_SCRIPT_COMPLEX,1,Scalar(255),2,8);
	int y_base;
	int* p = &y_base;
	Size size=getTextSize(text, FONT_HERSHEY_SCRIPT_COMPLEX, 1, 2, p);

 

 

 

 

 

 

 

 

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