Minor change to compile with the current version of OpenCV.

src/blob_detector_alg.cpp

@@ -68,7 +68,7 @@ void BlobDetectorAlgorithm::blob_detector(const cv::Mat& img,cv::Mat &img_out,ir
 
   this->lock();
   cv::Ptr<cv::SimpleBlobDetector> detector = cv::SimpleBlobDetector::create(this->params);
-  cvtColor(img,img_hsv,CV_RGB2HSV);
+  cvtColor(img,img_hsv,cv::COLOR_BGR2RGB);
   cv::inRange(img_hsv,cv::Scalar(this->h_min,this->s_min,this->v_min), cv::Scalar(this->h_max,this->s_max,this->v_max),img_bin);
   cv::bitwise_not(img_bin,img_bin_inv);
   detector->detect(img_bin_inv, keypoints);