Implemented traffic sign detector (red signs)

modules/traffic-sign-detector/traffic_sign_detector.cpp

@@ -0,0 +1,108 @@
+#include "traffic_sign_detector.h"
+
+vector<Rect> TrafficSignDetector::GetRedTrafficSigns(Mat image) {
+
+	Mat red_mask = GetRedMask(image);
+	vector<vector<Point> > contours;
+	vector<Point> approx;
+	vector<Vec4i> hierarchy;
+	vector<Rect> detected_signs;
+
+	erode(red_mask, red_mask, Mat(), Point(-1, -1), 1, 1, 1);
+	dilate(red_mask, red_mask, Mat(), Point(-1, -1), 4, 1, 1);
+
+	// RETR_TREE: Creates a full family hierarchy list.
+	// CV_CHAIN_APPROX_SIMPLE: compresses horizontal, vertical, 
+	// and diagonal segments and leaves only their end points.
+	// CV_CHAIN_APPROX_NONE: stores absolutely all the contour points.
+	// Hierarchy: [Next, Previous, First_Child, Parent]
+	findContours(red_mask.clone(), contours, hierarchy, RETR_TREE, 
+		CV_CHAIN_APPROX_SIMPLE);
+
+#ifdef DEBUG	
+	Mat convex_hull = image.clone();
+#endif
+
+	for (int ci = 0; ci < contours.size(); ++ci) {
+
+#ifdef DEBUG	
+		vector<vector<Point> > hull(contours.size());
+		convexHull(contours[ci], hull[ci], false);
+		drawContours(convex_hull, hull, ci, Scalar(0, 255, 0));
+#endif
+		// If contour has at least one child, then draw it
+		if (hierarchy[ci][2] != -1) {
+
+			// With contour approximation will remove small curves
+			// Maximum distance from contour to approximated contour: %20
+			approxPolyDP(contours[hierarchy[ci][2]], approx,
+				arcLength(contours[hierarchy[ci][2]], true) * 0.2, true);
+
+			// Detected triangular traffic sign
+			if (approx.size() == 3) {
+				detected_signs.push_back(boundingRect(contours[ci]));
+#ifdef DEBUG	
+				Rect bounding_rect = boundingRect(contours[ci]);
+				rectangle(image, bounding_rect.tl(), bounding_rect.br(), 
+					Scalar(0, 255, 0), 2);
+				cout << "triangle" << endl;
+#endif
+			}
+
+			// Detected circular traffic sign - if current contour is circular and 
+			// double of its childs area is greater than its own area
+			if (approx.size() == 2 
+				&& contours[hierarchy[ci][2]].size() * 2 > contours[ci].size()) {
+
+				detected_signs.push_back(boundingRect(contours[ci]));
+#ifdef DEBUG
+				Rect bounding_rect = boundingRect(contours[ci]);
+				rectangle(image, bounding_rect.tl(), bounding_rect.br(), 
+					Scalar(0, 255, 0), 2);
+				cout << "circle" << endl;
+#endif
+			}
+		}
+	}
+
+#ifdef DEBUG	
+	while (true) {
+		imshow("mask", red_mask);
+		imshow("result", image);
+		imshow("hull", convex_hull);
+		waitKey(30);
+	}
+#endif
+
+	return detected_signs;
+}
+
+vector<Rect> TrafficSignDetector::GetBlueTrafficSigns(Mat image) {
+
+}
+
+Mat TrafficSignDetector::GetRedMask(Mat image) {
+
+	// Hue and sturation tresholds
+	Mat tresh_hue_fst,
+		tresh_hue_snd,
+		tresh_saturation,
+		hsv;
+
+	vector<Mat> channels;
+
+	// Convert image to HSV, split it to channels
+	cvtColor(image, hsv, CV_BGR2HSV);
+	split(hsv, channels);
+
+	// Hue values between 0° to 25° and 335° to 360°
+	tresh_hue_fst = channels[0] < 25 / 2.0f;
+	tresh_hue_snd = channels[0] > 335 / 2.0f;
+	tresh_saturation = channels[1] > 50;
+
+	return (tresh_hue_fst | tresh_hue_snd) & tresh_saturation;
+}
+
+Mat TrafficSignDetector::GetBlueMask(Mat image) {
+
+}

modules/traffic-sign-detector/traffic_sign_detector.h

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+#pragma once
+
+#ifdef DEBUG	
+#include <iostream>
+#endif
+#include <opencv2/opencv.hpp>
+
+using namespace std;
+using namespace cv;
+
+class TrafficSignDetector
+{
+public:
+	// Returns the bounding rectangles for detected red traffic signs
+	static vector<Rect> GetRedTrafficSigns(Mat image);
+	static vector<Rect> GetBlueTrafficSigns(Mat image);
+
+private:
+	// Returns a binary image in which 
+	// 1 corresponds to red area, 0 corresponds to other colors
+	static Mat GetRedMask(Mat image);
+	static Mat GetBlueMask(Mat image);
+};