Add Rectangle Object Detection.cpp

Author: BBuf

Feature Extraction/Rectangle Object Detection.cpp

@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <opencv2/opencv.hpp>
+
+using namespace std;
+using namespace cv;
+
+//计算两个向量pt0->pt1和pt0->pt2的夹角
+double angle(Point pt1, Point pt2, Point pt0) {
+	double dx1 = pt1.x - pt0.x;
+	double dy1 = pt1.y - pt0.y;
+	double dx2 = pt2.x - pt0.x;
+	double dy2 = pt2.y - pt0.y;
+	return (dx1*dx2 + dy1*dy2) / sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
+}
+
+const int N = 5;
+
+int main() {
+	// 读入图片
+	Mat src = cv::imread("F:\\2stickies.jpg");
+	// 记录长宽
+	int row = src.rows;
+	int col = src.cols;
+	// 存储矩阵
+	vector <vector<Point> > squares;
+	// 将原图转化为灰度图
+	Mat gray(row, col, CV_8UC1);
+	cvtColor(src, gray, CV_BGRA2GRAY);
+	// 中值滤波，半径为9
+	medianBlur(gray, gray, 9);
+	cv::imshow("median", gray);
+	waitKey(0);
+	// 存储图像的轮廓
+	vector <vector<Point> > contours;
+	Mat gray0 = gray.clone();
+	for (int l = 0; l < N; l++) {
+		if (l == 0) {
+			// 先执行Canny边缘检测
+			Canny(gray0, gray, 5, 50, 5);
+			// 形态学操作
+			dilate(gray, gray, Mat(), Point(-1, -1));
+		}
+		else {
+			gray = gray0 >= (l + 1) * 255 / N;
+		}
+		// 寻找图像的轮廓
+		findContours(gray, contours, RETR_LIST, CHAIN_APPROX_SIMPLE);
+		// 存储多边形的点
+		vector <Point> approx;
+		for (size_t i = 0; i < contours.size(); i++) {
+			approxPolyDP(Mat(contours[i]), approx, arcLength(Mat(contours[i]), true) * 0.02, true);
+			if (approx.size() == 4 && fabs(contourArea(Mat(approx))) > 1000 &&
+				isContourConvex(Mat(approx))) {
+				// 找到多边形最大的角
+				double maxCosine = 0;
+				for (int j = 2; j < 5; j++) {
+					double cosine = fabs(angle(approx[j % 4], approx[j - 2], approx[j - 1]));
+					maxCosine = max(maxCosine, cosine);
+				}
+				//如果余弦值小于0.3，就判断为矩阵
+				if (maxCosine < 0.3) {
+					squares.push_back(approx);
+				}
+			}
+		}
+	}
+	printf("%d\n", squares.size());
+	// 把矩形画在原图上
+	for (size_t i = 0; i < squares.size(); i++)
+	{
+		const Point* p = &squares[i][0];
+		int n = (int)squares[i].size();
+		//dont detect the border
+		printf("%d %d\n", p->x, p->y);
+		if (p->x > 3 && p->y > 3)
+			polylines(src, &p, &n, 1, true, Scalar(0, 255, 0), 3, LINE_AA);
+	}
+	imshow("result", src);
+	waitKey(0);
+	return 0;
+}