diff --git a/ccv/sheet5/gauss_pyramid.cpp b/ccv/sheet5/gauss_pyramid.cpp
index 108f51b..a45ff2d 100644
--- a/ccv/sheet5/gauss_pyramid.cpp
+++ b/ccv/sheet5/gauss_pyramid.cpp
@@ -14,11 +14,21 @@ gauss_pyramid::gauss_pyramid(cv::Mat img, float sigma, int number_of_layers)
   }
 }
 
+cv::Mat gauss_pyramid::get(int layer) const
+{
+  return _layers.at((unsigned long) layer);
+}
+
 cv::Mat gauss_pyramid::get(int layer)
 {
   return _layers.at((unsigned long) layer);
 }
 
+unsigned long gauss_pyramid::get_number_of_layers() const
+{
+  return _layers.size();
+}
+
 unsigned long gauss_pyramid::get_number_of_layers()
 {
   return _layers.size();
diff --git a/ccv/sheet5/gauss_pyramid.h b/ccv/sheet5/gauss_pyramid.h
index 4583332..7a54d26 100644
--- a/ccv/sheet5/gauss_pyramid.h
+++ b/ccv/sheet5/gauss_pyramid.h
@@ -10,7 +10,9 @@ private:
 public:
     gauss_pyramid();
     gauss_pyramid(cv::Mat img, float sigma, int number_of_layers);
+    cv::Mat get(int layer) const;
     cv::Mat get(int layer);
+    unsigned long get_number_of_layers() const;
     unsigned long get_number_of_layers();
 };