Adding example 12-02

CMakeLists.txt

@@ -35,6 +35,7 @@ add_executable( example_11-01 example_11-01.cpp )
 add_executable( example_11-02 example_11-02.cpp )
 add_executable( example_11-03 example_11-03.cpp )
 add_executable( example_12-01 example_12-01.cpp )
+add_executable( example_12-02 example_12-02.cpp )
 add_executable( example_16-01 example_16-01.cpp )
 
 target_link_libraries( example_02-01 ${OpenCV_LIBS} )
@@ -65,6 +66,7 @@ target_link_libraries( example_11-01 ${OpenCV_LIBS} )
 target_link_libraries( example_11-02 ${OpenCV_LIBS} )
 target_link_libraries( example_11-03 ${OpenCV_LIBS} )
 target_link_libraries( example_12-01 ${OpenCV_LIBS} )
+target_link_libraries( example_12-02 ${OpenCV_LIBS} )
 target_link_libraries( example_16-01 ${OpenCV_LIBS} )
 
 

example_12-02.cpp

@@ -0,0 +1,44 @@
+// Example 12-2. Using cv::HoughCircles() to return a sequence of circles found in a
+// grayscale image
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+#include <math.h>
+
+using namespace cv;
+using namespace std;
+
+int main(int argc, char** argv) {
+
+  if(argc != 2) {
+  cout << "Hough Circle detect\nUsage: " <<argv[0] <<" <imagename>\n" << endl;
+  return -1;
+  }
+
+  cv::Mat src, image;
+
+  src = cv::imread( argv[1], 1 );
+  if( src.empty() ) { cout << "Cannot load " << argv[1] << endl; return -1; }
+
+  cv::cvtColor(src, image, cv::COLOR_BGR2GRAY);
+  cv::GaussianBlur(image, image, Size(5,5), 0, 0);
+
+  vector<cv::Vec3f> circles;
+  cv::HoughCircles(image, circles, cv::HOUGH_GRADIENT, 2, image.cols/4);
+
+  for( size_t i = 0; i < circles.size(); ++i ) {
+    cv::circle(
+      src,
+      cv::Point(cvRound(circles[i][0]), cvRound(circles[i][1])),
+      cvRound(circles[i][2]),
+      cv::Scalar(0,0,255),
+      2,
+      cv::LINE_AA
+    );
+  }
+
+  cv::imshow( "Hough Circles", src);
+  cv::waitKey(0);
+
+  return 0;
+}