From 30737542ed3ccbc854a62fb42ea0bcfb8492a448 Mon Sep 17 00:00:00 2001
From: novak_99 <cooljohn312@gmail.com>
Date: Sun, 21 Nov 2021 22:43:51 -0800
Subject: [PATCH] Added gaussian filter, added laplacian filter.

---
 MLPP/Convolutions/Convolutions.cpp | 20 ++++++++++++++++++++
 MLPP/Convolutions/Convolutions.hpp |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/MLPP/Convolutions/Convolutions.cpp b/MLPP/Convolutions/Convolutions.cpp
index 9e3d6d9..b5ea669 100644
--- a/MLPP/Convolutions/Convolutions.cpp
+++ b/MLPP/Convolutions/Convolutions.cpp
@@ -8,6 +8,7 @@
 #include "Convolutions/Convolutions.hpp"
 #include "LinAlg/LinAlg.hpp"
 #include "Stat/Stat.hpp"
+#include <cmath>
 
 namespace MLPP{
 
@@ -225,6 +226,25 @@ namespace MLPP{
         return pooledMap; 
     }
 
+    double Convolutions::gaussian2D(double x, double y, double std){
+        double std_sq = std * std;
+        return 1/(2 * M_PI * std_sq) * std::exp(-(x * x + y * y)/2 * std_sq);
+    }
+
+    std::vector<std::vector<double>> Convolutions::gaussianFilter2D(int size, double std){
+        std::vector<std::vector<double>> filter; 
+        filter.resize(size);
+        for(int i = 0; i < filter.size(); i++){
+            filter[i].resize(size);
+        }
+        for(int i = 0; i < size; i++){
+            for(int j = 0; j < size; j++){
+                filter[i][j] = gaussian2D(i - (size-1)/2, (size-1)/2 - j, std);
+            }
+        }
+        return filter;
+    }
+
     std::vector<std::vector<double>> Convolutions::getPrewittHorizontal(){
         return prewittHorizontal;
     }
diff --git a/MLPP/Convolutions/Convolutions.hpp b/MLPP/Convolutions/Convolutions.hpp
index 913c965..fb37465 100644
--- a/MLPP/Convolutions/Convolutions.hpp
+++ b/MLPP/Convolutions/Convolutions.hpp
@@ -14,6 +14,9 @@ namespace MLPP{
             double globalPool(std::vector<std::vector<double>> input, std::string type);
             std::vector<double> globalPool(std::vector<std::vector<std::vector<double>>> input, std::string type);
 
+            double gaussian2D(double x, double y, double std);
+            std::vector<std::vector<double>> gaussianFilter2D(int size, double std);
+
             std::vector<std::vector<double>> getPrewittHorizontal();
             std::vector<std::vector<double>> getPrewittVertical();
             std::vector<std::vector<double>> getSobelHorizontal();