C++ OpenCV实战之形状识别

	Mat gray;
	cvtColor(src, gray, COLOR_BGR2GRAY);

	Mat gaussian;
	GaussianBlur(gray, gaussian, Size(3, 3), 0);

	Mat thresh;
	threshold(gaussian, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);

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

//基础几何形状识别
bool Pattern_Recognition(Mat& src)
{
	//图像预处理
	Mat gray;
	cvtColor(src, gray, COLOR_BGR2GRAY);

	Mat gaussian;
	GaussianBlur(gray, gaussian, Size(3, 3), 0);

	Mat thresh;
	threshold(gaussian, thresh, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);

	//轮廓查找
	vector<vector<Point>>contours;//轮廓点集
	findContours(thresh, contours, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);
	vector<vector<Point>>conPoly(contours.size());//多边形逼近结果，与轮廓一一对应

	for (int i = 0; i < contours.size(); i++)
	{
		double area = contourArea(contours[i]); //轮廓面积

		if (area > 1000)
		{
			Rect rect = boundingRect(contours[i]);//外界矩形

			double ratio = double(rect.width) / double(rect.height);//长宽比

			double peri = arcLength(contours[i], true);//周长

			approxPolyDP(contours[i], conPoly[i], 0.02 * peri, true);//多边形近似

			int objSize = conPoly[i].size();//折线数--通过判断轮廓有几条边来识别图形

			string objName;
			Scalar color;
			if (objSize == 3)
			{
				objName = "Triangle";//三角形
				color = Scalar(0, 0, 255);
			}
			if (objSize == 4)
			{
				//通过长宽比判断正方形/长方形
				if (ratio > 0.99 && ratio < 1.01)
				{
					objName = "Square";//正方形
					color = Scalar(0, 255, 255);
				}
				else
				{
					objName = "Rectangle";//长方形
					color = Scalar(0, 255, 0);
				}
			}
			if (objSize == 8)
			{
				objName = "Circle";//圆形
				color = Scalar(255, 255, 0);
			}
			if (objSize == 10)
			{
				objName = "Star";//星形
				color = Scalar(255, 0, 255);
			}

			//效果绘制
			rectangle(src, rect, color, 2);
			putText(src, objName, rect.tl(), FONT_HERSHEY_SIMPLEX, 1, color, 2);
		}
	}

	return true;
}

int main()
{
	Mat src = imread("src.jpeg");
	if (src.empty())
	{
		cout << "No Image!" << endl;
		system("pause");
		return -1;
	}
	
	if (!Pattern_Recognition(src))return false;

	namedWindow("test", WINDOW_NORMAL);
	imshow("test", src);
	waitKey(0);
	system("pause");
	return 0;
}