The logistic regression validator (not tested)

include/ball_tracking/img_proc.hpp

@@ -22,6 +22,19 @@ namespace ball_tracking {
    */
   cv::Mat map_channel_quad(cv::InputArray src, cv::InputArray mean, cv::InputArray S);
 
+  /**
+   * @brief Applies a pixel-wise logistic regression with quadratic features to the source
+   * image and returns a single-channel image with the log-probabilities
+   *
+   * @param[in] src The source image
+   * @param[in] bkg A background image (Without the ball)
+   * @param[in] weights Vector of weights of logistic regression
+   *
+   * @returns a new image where every pixel corresponds to the log-probability of the
+   * pixel being a ball according to the trained classifier 
+   */
+  cv::Mat quadf_log_reg(cv::InputArray src, cv::InputArray bkg, cv::InputArray weights);
+
   
   /**
    * @brief Produces a single channel image highlighting the possible position of the ball

src/img_proc.cpp

@@ -34,4 +34,31 @@ namespace ball_tracking {
     return ans;
   }
 
+  cv::Mat quadf_log_reg(cv::InputArray _src, cv::InputArray _bkg, cv::InputArray _weights) {
+    Mat src = _src.getMat(), bkg = _bkg.getMat(), tmp_weight = _weights.getMat();
+    const unsigned int channels = src.channels();
+    CV_Assert(channels == 3);
+    CV_Assert(src.rows == bkg.rows && src.cols == bkg.cols);
+    double w[28];
+    copy(tmp_weight.begin<double>(), tmp_weight.end<double>(), w);
+
+    Mat ans(src.rows, src.cols, CV_64FC1);
+    MatIterator_<Vec3b> it=src.begin<Vec3b>(), end=src.end<Vec3b>();
+    MatIterator_<Vec3b> it_bkg=bkg.begin<Vec3b>();
+    MatIterator_<double> it_ans = ans.begin<double>();
+    for (; it != end; it++, it_ans++, it_bkg++) {
+      double sum = 0.0;
+      double lfeat[7] = {(*it)[0]/255.0, (*it)[1]/255.0, (*it)[2]/255.0, 
+        (*it_bkg)[0]/255.0, (*it_bkg)[1]/255.0, (*it_bkg)[2]/255.0, 1.0};
+      double* wptr = w;
+      for (unsigned int i=0; i<7; i++) {
+        for (unsigned int j=i; j<channels; j++, wptr++) {
+          sum += (*wptr) * lfeat[i] * lfeat[j];
+        }
+      }
+      *it_ans = sum;
+    }
+    return ans;
+  }
+
 };