diff --git a/ccv/sheet4/lab_pyramid.cpp b/ccv/sheet4/lab_pyramid.cpp
index b302b44..fc759bc 100644
--- a/ccv/sheet4/lab_pyramid.cpp
+++ b/ccv/sheet4/lab_pyramid.cpp
@@ -33,3 +33,54 @@ gauss_pyramid lab_pyramid::get_pyramid(int channel)
       throw std::invalid_argument( "received invalid channel value, use COLOR_L, COLOR_A or COLOR_B" );
   }
 }
+
+void static lab_pyramid::compute_dog(lab_pyramid center, lab_pyramid surround, int number_of_layers) {
+  // L channel
+  gauss_pyramid center_l = center.get_pyramid(COLOR_L);
+  gauss_pyramid surround_l = surround.get_pyramid(COLOR_L);
+
+  // A channel
+  gauss_pyramid center_a = center.get_pyramid(COLOR_A);
+  gauss_pyramid surround_a = surround.get_pyramid(COLOR_A);
+
+  // A channel
+  gauss_pyramid center_b = center.get_pyramid(COLOR_B);
+  gauss_pyramid surround_b = surround.get_pyramid(COLOR_B);
+
+  for (int layer = 0; layer < number_of_layers; layer++) {
+    // L channel
+    cv::Mat center_layer_mat = center_l.get(layer);
+    cv::Mat surround_layer_mat = surround_l.get(layer);
+    cv::Mat dog_raw = center_layer_mat - surround_layer_mat;
+    cv::Mat dog_final;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _cs_contrast_l.push_back(dog_final);
+    dog_raw = surround_layer_mat - center_layer_mat;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _sc_contrast_l.push_back(dog_final);
+
+    // A channel
+    center_layer_mat = center_a.get(layer);
+    surround_layer_mat = surround_a.get(layer);
+    dog_raw = center_layer_mat - surround_layer_mat;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _cs_contrast_a.push_back(dog_final);
+    dog_raw = surround_layer_mat - center_layer_mat;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _sc_contrast_a.push_back(dog_final);
+
+    // B channel
+    center_layer_mat = center_b.get(layer);
+    surround_layer_mat = surround_b.get(layer);
+    dog_raw = center_layer_mat - surround_layer_mat;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _cs_contrast_b.push_back(dog_final);
+    dog_raw = surround_layer_mat - center_layer_mat;
+    cv::threshold(dog_raw, dog_final, 0, 1, cv::THRESH_TOZERO);
+    _sc_contrast_b.push_back(dog_final);
+  }
+}
+
+void static lab_pyramid::visualize_dog() {
+
+}
diff --git a/ccv/sheet4/lab_pyramid.h b/ccv/sheet4/lab_pyramid.h
index 3649e5f..aaf2583 100644
--- a/ccv/sheet4/lab_pyramid.h
+++ b/ccv/sheet4/lab_pyramid.h
@@ -10,6 +10,12 @@ private:
     cv::Mat _inputImage_float;
     cv::Mat _imageChannels[3];
     gauss_pyramid _pyramids[3];
+    static std::vector<cv::Mat> _cs_contrast_l;
+    static std::vector<cv::Mat> _sc_contrast_l;
+    static std::vector<cv::Mat> _cs_contrast_a;
+    static std::vector<cv::Mat> _sc_contrast_a;
+    static std::vector<cv::Mat> _cs_contrast_b;
+    static std::vector<cv::Mat> _sc_contrast_b;
 public:
     const static int COLOR_L = 0;
     const static int COLOR_A = 1;
@@ -44,6 +50,20 @@ public:
      * @return the gaussian_pyramid for the given channel
      */
     gauss_pyramid get_pyramid(int channel);
+
+    /**
+     * Computes the center-surround and surround-center contrasts and stores them for later use.
+     *
+     * @param center the center pyramid
+     * @param surround the surround pyramid
+     * @param number_of_layers the number of layers used to create the two pyramids
+     */
+    void static compute_dog(lab_pyramid center, lab_pyramid surround, int number_of_layers);
+
+    /**
+     * Visualizes the center-surround and surround-center contrasts. They have to be computed first.
+     */
+    void static visualize_dog();
 };