OpenCV-绘制奥运五环（带套接效果）

Posted 2021-09-16 翟天保Steven

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绘制逻辑

奥运五环由5个同心圆套接组成，有蓝、黄、黑、绿、红5种颜色。环从左到右互相套接，上面是蓝、黑、红环，下面是是黄、绿环。整个造形为一个底部小的规则梯形。大多数人绘制一般只将五个同心圆按顺序排布，但是真正的五环是套接而成，所以本文绘制了带套接效果的奥运五环。

首先输入绘制的区域信息和五环的环宽，限制下区域宽高和环宽尺寸，避免程序崩溃；其次，正常绘制五个不同颜色的同心圆，以及各自的掩膜图；将交叉的两个环取交集建立交集掩膜图，共有4个交集，分别是蓝色和黄色、黄色和黑色、黑色和绿色、绿色和红色；按照交集区域颜色的优先级，清除交集掩膜图中的非操作区域，对操作区域进行颜色重绘，完毕。

话不多说，下方为具体实现函数和测试代码。

功能函数代码

// 绘制奥运五环
cv::Mat DrawOlympicRings(cv::Mat src,cv::Rect rect,int w)
{
	if (rect.width < 400)
		rect.width = 400;
	if (rect.height < 400)
		rect.height = 400;
	// 设置五环半径
	int r = min(rect.width, rect.height) / 7;
	if (w > r / 5)
		w = r / 5;
	cv::Mat result = src.clone();
	int row = result.rows;
	int col = result.cols;
	// 蓝色为1，黑色为2，红色为3，黄色为4，绿色为5
	cv::Point point2 = cv::Point(int(rect.x + rect.width / 2), int(rect.y + rect.height / 2 - 0.55*r));
	cv::Point point4 = cv::Point(int(rect.x + rect.width / 2 - 1.1*r), int(rect.y + rect.height / 2 + 0.55*r));
	cv::Point point5 = cv::Point(int(rect.x + rect.width / 2 + 1.1*r), int(rect.y + rect.height / 2 + 0.55*r));
	cv::Point point1 = cv::Point(int(rect.x + rect.width / 2 - 2.2*r), int(rect.y + rect.height / 2 - 0.55*r));
	cv::Point point3 = cv::Point(int(rect.x + rect.width / 2 + 2.2*r), int(rect.y + rect.height / 2 - 0.55*r));
	
	// 初步绘制同心圆
	DrawConcentricCircle(result, point1, r - w, r, cv::Scalar(255, 0, 0), -1, 16);
	DrawConcentricCircle(result, point2, r - w, r, cv::Scalar(0, 0, 0), -1, 16);
	DrawConcentricCircle(result, point3, r - w, r, cv::Scalar(0, 0, 255), -1, 16);
	DrawConcentricCircle(result, point4, r - w, r, cv::Scalar(0, 255, 255), -1, 16);
	DrawConcentricCircle(result, point5, r - w, r, cv::Scalar(0, 255, 0), -1, 16);

	// 绘制五环掩膜位置
	cv::Mat temp = result.clone();
	cv::Mat mask1 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask1, point1, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask2 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask2, point2, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask3 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask3, point3, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask4 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask4, point4, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask5 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask5, point5, r - w, r, cv::Scalar(255, 255, 255), -1, 16);

	// 五环交集
	cv::Mat blury  = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat blacky = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat blackg = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat greenr = cv::Mat::zeros(result.size(), CV_8UC1);
	for (int i = rect.y; i < (rect.y+rect.height); ++i)
	{
		for (int j = rect.x; j < (rect.x+rect.width); ++j)
		{
			if (mask1.at<Vec3b>(i, j)[0] == 255 && mask4.at<Vec3b>(i, j)[0] == 255)
				blury .at<uchar>(i, j) = 255;
			if (mask2.at<Vec3b>(i, j)[0] == 255 && mask4.at<Vec3b>(i, j)[0] == 255)
				blacky.at<uchar>(i, j) = 255;
			if (mask2.at<Vec3b>(i, j)[0] == 255 && mask5.at<Vec3b>(i, j)[0] == 255)
				blackg.at<uchar>(i, j) = 255;
			if (mask3.at<Vec3b>(i, j)[0] == 255 && mask5.at<Vec3b>(i, j)[0] == 255)
				greenr.at<uchar>(i, j) = 255;
		}
	}

	// 目前黄环和绿环压在蓝黑红三环上面
	// 按照五环交叠的规律，消除对应的重叠区，使上面的三环在对应位置反压下面两环
	clearArea(blury , 0);
	clearArea(blacky, 1);
	clearArea(blackg, 0);
	clearArea(greenr, 1);

	for (int i = rect.y; i < (rect.y + rect.height); ++i)
	{
		for (int j = rect.x; j < (rect.x + rect.width); ++j)
		{
			uchar *m1 = blury .ptr<uchar>(i);
			uchar *m2 = blacky.ptr<uchar>(i);
			uchar *m3 = blackg.ptr<uchar>(i);
			uchar *m4 = greenr.ptr<uchar>(i);
			if (m1[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 255;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 0;
			}
			if (m2[j] == 255|| m3[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 0;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 0;
			}
			if (m4[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 0;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 255;
			}
		}
	}
	return result;
}

// 绘制同心圆
void DrawConcentricCircle(cv::Mat mask, const cv::Point2i &center, int radius1, int radius2, const cv::Scalar &color, int thickness, int linetype)
{
	// 创建画布
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);

	// 计算内径和外径
	int inradius = min(radius1, radius2);
	int outradius = max(radius1, radius2);

	// 分情况讨论
	// 当thickness大于0时，绘制的是两个圆型线条组成的同心圆，不需填充
	if (thickness > 0)
	{
		cv::circle(mask, center, outradius, color, thickness, linetype);
		cv::circle(mask, center, inradius, color, thickness, linetype);
	}
	// 当thickness小于0，一般为-1，绘制的是填充同心圆，内圆不能有填充色
	else {
		cv::circle(canvas, center, outradius, cv::Scalar(255), -1, linetype);
		cv::circle(canvas, center, inradius, cv::Scalar(0), -1, linetype);
		int row = mask.rows;
		int col = mask.cols;
		for (int i = 0; i < row; ++i)
		{
			for (int j = 0; j < col; ++j)
			{
				uchar *m = canvas.ptr<uchar>(i);
				if (m[j] == 255)
				{
					mask.at<Vec3b>(i, j)[0] = static_cast<uchar>(color[0]);
					mask.at<Vec3b>(i, j)[1] = static_cast<uchar>(color[1]);
					mask.at<Vec3b>(i, j)[2] = static_cast<uchar>(color[2]);
				}

			}
		}
	}
}

// 清除第id个连通区
void clearArea(cv::Mat& mask, int id)
{
	std::vector<std::vector<cv::Point> > contours;  // 创建轮廓容器
	std::vector<cv::Vec4i> 	hierarchy;

	cv::findContours(mask, contours, hierarchy, cv::RETR_EXTERNAL, cv::CHAIN_APPROX_NONE, cv::Point());
	if (!contours.empty() && !hierarchy.empty())
	{
		if (id<contours.size())
		{
			cv::Rect rect = cv::boundingRect(cv::Mat(contours[id]));
			for (int i = rect.y; i < rect.y + rect.height; i++)
			{
				uchar *output_data = mask.ptr<uchar>(i);
				for (int j = rect.x; j < rect.x + rect.width; j++)
				{
					// 将连通区的值置0
					if (output_data[j] == 255)
					{
						output_data[j] = 0;
					}
				}
			}
		}
	}
}

C++测试代码

#include <iostream>
#include <opencv2/opencv.hpp>
#include <time.h>

using namespace std;
using namespace cv;

cv::Mat DrawOlympicRings(cv::Mat src, cv::Rect rect, int w);
void DrawConcentricCircle(cv::Mat mask, const cv::Point2i &center, int radius1, int radius2, const cv::Scalar &color, int thickness, int linetype);
void clearArea(cv::Mat& mask, int id);

int main()
{
	cv::Mat src = imread("test.jpg");
	cv::Mat result = src.clone();
	cv::Rect rect = cv::Rect(10, 10, 800, 800);
	int width = 20;
	clock_t start, end;
	start = clock();
	result = DrawOlympicRings(result,rect,width);
	end = clock();
	double diff = end - start;
	cout << "time:" << diff / CLOCKS_PER_SEC << endl;
	imshow("original", src);
	imshow("result", result);
	waitKey(0);
	system("pause");
	return 0;
}



// 绘制奥运五环
cv::Mat DrawOlympicRings(cv::Mat src,cv::Rect rect,int w)
{
	if (rect.width < 400)
		rect.width = 400;
	if (rect.height < 400)
		rect.height = 400;
	// 设置五环半径
	int r = min(rect.width, rect.height) / 7;
	if (w > r / 5)
		w = r / 5;
	cv::Mat result = src.clone();
	int row = result.rows;
	int col = result.cols;
	// 蓝色为1，黑色为2，红色为3，黄色为4，绿色为5
	cv::Point point2 = cv::Point(int(rect.x + rect.width / 2), int(rect.y + rect.height / 2 - 0.55*r));
	cv::Point point4 = cv::Point(int(rect.x + rect.width / 2 - 1.1*r), int(rect.y + rect.height / 2 + 0.55*r));
	cv::Point point5 = cv::Point(int(rect.x + rect.width / 2 + 1.1*r), int(rect.y + rect.height / 2 + 0.55*r));
	cv::Point point1 = cv::Point(int(rect.x + rect.width / 2 - 2.2*r), int(rect.y + rect.height / 2 - 0.55*r));
	cv::Point point3 = cv::Point(int(rect.x + rect.width / 2 + 2.2*r), int(rect.y + rect.height / 2 - 0.55*r));
	
	// 初步绘制同心圆
	DrawConcentricCircle(result, point1, r - w, r, cv::Scalar(255, 0, 0), -1, 16);
	DrawConcentricCircle(result, point2, r - w, r, cv::Scalar(0, 0, 0), -1, 16);
	DrawConcentricCircle(result, point3, r - w, r, cv::Scalar(0, 0, 255), -1, 16);
	DrawConcentricCircle(result, point4, r - w, r, cv::Scalar(0, 255, 255), -1, 16);
	DrawConcentricCircle(result, point5, r - w, r, cv::Scalar(0, 255, 0), -1, 16);

	// 绘制五环掩膜位置
	cv::Mat temp = result.clone();
	cv::Mat mask1 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask1, point1, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask2 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask2, point2, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask3 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask3, point3, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask4 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask4, point4, r - w, r, cv::Scalar(255, 255, 255), -1, 16);
	cv::Mat mask5 = cv::Mat::zeros(result.size(), CV_8UC3);
	DrawConcentricCircle(mask5, point5, r - w, r, cv::Scalar(255, 255, 255), -1, 16);

	// 五环交集
	cv::Mat blury  = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat blacky = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat blackg = cv::Mat::zeros(result.size(), CV_8UC1);
	cv::Mat greenr = cv::Mat::zeros(result.size(), CV_8UC1);
	for (int i = rect.y; i < (rect.y+rect.height); ++i)
	{
		for (int j = rect.x; j < (rect.x+rect.width); ++j)
		{
			if (mask1.at<Vec3b>(i, j)[0] == 255 && mask4.at<Vec3b>(i, j)[0] == 255)
				blury .at<uchar>(i, j) = 255;
			if (mask2.at<Vec3b>(i, j)[0] == 255 && mask4.at<Vec3b>(i, j)[0] == 255)
				blacky.at<uchar>(i, j) = 255;
			if (mask2.at<Vec3b>(i, j)[0] == 255 && mask5.at<Vec3b>(i, j)[0] == 255)
				blackg.at<uchar>(i, j) = 255;
			if (mask3.at<Vec3b>(i, j)[0] == 255 && mask5.at<Vec3b>(i, j)[0] == 255)
				greenr.at<uchar>(i, j) = 255;
		}
	}

	// 目前黄环和绿环压在蓝黑红三环上面
	// 按照五环交叠的规律，消除对应的重叠区，使上面的三环在对应位置反压下面两环
	clearArea(blury , 0);
	clearArea(blacky, 1);
	clearArea(blackg, 0);
	clearArea(greenr, 1);

	for (int i = rect.y; i < (rect.y + rect.height); ++i)
	{
		for (int j = rect.x; j < (rect.x + rect.width); ++j)
		{
			uchar *m1 = blury .ptr<uchar>(i);
			uchar *m2 = blacky.ptr<uchar>(i);
			uchar *m3 = blackg.ptr<uchar>(i);
			uchar *m4 = greenr.ptr<uchar>(i);
			if (m1[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 255;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 0;
			}
			if (m2[j] == 255|| m3[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 0;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 0;
			}
			if (m4[j] == 255)
			{
				result.at<Vec3b>(i, j)[0] = 0;
				result.at<Vec3b>(i, j)[1] = 0;
				result.at<Vec3b>(i, j)[2] = 255;
			}
		}
	}
	return result;
}

// 绘制同心圆
void DrawConcentricCircle(cv::Mat mask, const cv::Point2i &center, int radius1, int radius2, const cv::Scalar &color, int thickness, int linetype)
{
	// 创建画布
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);

	// 计算内径和外径
	int inradius = min(radius1, radius2);
	int outradius = max(radius1, radius2);

	// 分情况讨论
	// 当thickness大于0时，绘制的是两个圆型线条组成的同心圆，不需填充
	if (thickness > 0)
	{
		cv::circle(mask, center, outradius, color, thickness, linetype);
		cv::circle(mask, center, inradius, color, thickness, linetype);
	}
	// 当thickness小于0，一般为-1，绘制的是填充同心圆，内圆不能有填充色
	else {
		cv::circle(canvas, center, outradius, cv::Scalar(255), -1, linetype);
		cv::circle(canvas, center, inradius, cv::Scalar(0), -1, linetype);
		int row = mask.rows;
		int col = mask.cols;
		for (int i = 0; i < row; ++i)
		{
			for (int j = 0; j < col; ++j)
			{
				uchar *m = canvas.ptr<uchar>(i);
				if (m[j] == 255)
				{
					mask.at<Vec3b>(i, j)[0] = static_cast<uchar>(color[0]);
					mask.at<Vec3b>(i, j)[1] = static_cast<uchar>(color[1]);
					mask.at<Vec3b>(i, j)[2] = static_cast<uchar>(color[2]);
				}

			}
		}
	}
}

// 清除第id个连通区
void clearArea(cv::Mat& mask, int id)
{
	std::vector<std::vector<cv::Point> > contours;  // 创建轮廓容器
	std::vector<cv::Vec4i> 	hierarchy;

	cv::findContours(mask, contours, hierarchy, cv::RETR_EXTERNAL, cv::CHAIN_APPROX_NONE, cv::Point());
	if (!contours.empty() && !hierarchy.empty())
	{
		if (id<contours.size())
		{
			cv::Rect rect = cv::boundingRect(cv::Mat(contours[id]));
			for (int i = rect.y; i < rect.y + rect.height; i++)
			{
				uchar *output_data = mask.ptr<uchar>(i);
				for (int j = rect.x; j < rect.x + rect.width; j++)
				{
					// 将连通区的值置0
					if (output_data[j] == 255)
					{
						output_data[j] = 0;
					}
				}
			}
		}
	}
}

测试效果

奥运五环完成啦，和图3是不是很接近，颜色可能有些许差异，只需要改变对应的RGB颜色即可。奥运五环的环上还有白边，可以通过重写同心圆函数DrawConcentricCircle来实现，我就不做啦，感兴趣的兄弟可以自行研究~

如果函数有什么可以改进完善的地方，非常欢迎大家指出，一同进步何乐而不为呢~

如果文章帮助到你了，可以点个赞让我知道，我会很快乐~加油！

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