diff --git a/bin/demo.cpp b/bin/demo.cpp
index 8d2413d..5a610cd 100644
--- a/bin/demo.cpp
+++ b/bin/demo.cpp
@@ -2,6 +2,12 @@
 
 int main( int argc, char** argv )
 {
+    if ( argc != 3 )
+    {
+        printf("Usage: ./demo BURST_FOLDER_PATH(no / at end) REFERENCE_IMAGE_PATH\n");
+        exit(1);
+    }
+
     hdrplus::hdrplus_pipeline pipeline;
-    pipeline.run_pipeline();
+    pipeline.run_pipeline( argv[1], argv[ 2 ]);
 }
\ No newline at end of file
diff --git a/include/hdrplus/align.h b/include/hdrplus/align.h
index 72b9b9f..587baa1 100644
--- a/include/hdrplus/align.h
+++ b/include/hdrplus/align.h
@@ -12,7 +12,17 @@ class align
 {
     public:
         align() = default;
-        void process( hdrplus::burst& burst_images, \
+        ~align() = default;
+
+        /**
+         * @brief Run alignment on burst of images
+         * 
+         * @param burst_images collection of burst images
+         * @param aligements alignment in pixel value pair. 
+         *      Outer most vector is per alternative image.
+         *      Inner most two vector is for horizontle & verticle tiles 
+         */
+        void process( const hdrplus::burst& burst_images, \
                       std::vector<std::vector<std::vector<std::pair<int, int>>>>& aligements );
 
         const std::vector<int> inv_scale_factors = { 1, 2, 2, 4 };
diff --git a/include/hdrplus/burst.h b/include/hdrplus/burst.h
index 0b9fd09..4dd7eea 100644
--- a/include/hdrplus/burst.h
+++ b/include/hdrplus/burst.h
@@ -19,7 +19,11 @@ class burst
         int reference_image_idx;
         std::vector<std::string> bayer_image_paths;
 
+        // Source bayer images & grayscale unpadded image
         std::vector<hdrplus::bayer_image> bayer_images;
+
+        // Image padded to tile size
+        // Use for alignment, merging, and finishing
         std::vector<cv::Mat> grayscale_images_pad;
 
 };
diff --git a/include/hdrplus/hdrplus_pipeline.h b/include/hdrplus/hdrplus_pipeline.h
index 0e992e3..9df420a 100644
--- a/include/hdrplus/hdrplus_pipeline.h
+++ b/include/hdrplus/hdrplus_pipeline.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <string>
 #include <opencv2/opencv.hpp> // all opencv header
 #include "hdrplus/burst.h"
 #include "hdrplus/align.h"
@@ -17,8 +18,9 @@ class hdrplus_pipeline
         hdrplus::finish finish_module;
     
     public:
-        void run_pipeline();
+        void run_pipeline( const std::string& burst_path, const std::string& reference_image_path  );
         hdrplus_pipeline() = default;
+        ~hdrplus_pipeline() = default;
 };
 
 } // namespace hdrplus
diff --git a/include/hdrplus/merge.h b/include/hdrplus/merge.h
index 0204c53..cd7bcec 100644
--- a/include/hdrplus/merge.h
+++ b/include/hdrplus/merge.h
@@ -1,6 +1,8 @@
 #pragma once
 
+#include <vector>
 #include <opencv2/opencv.hpp> // all opencv header
+#include "hdrplus/burst.h"
 
 namespace hdrplus
 {
@@ -9,6 +11,18 @@ class merge
 {
     public:
         merge() = default;
+        ~merge() = default;
+
+        /**
+         * @brief Run alignment on burst of images
+         * 
+         * @param burst_images collection of burst images
+         * @param aligements alignment in pixel value pair. 
+         *      Outer most vector is per alternative image.
+         *      Inner most two vector is for horizontle & verticle tiles 
+         */
+        void process( const hdrplus::burst& burst_images, \
+                      std::vector<std::vector<std::vector<std::pair<int, int>>>>& aligements );
 };
 
 } // namespace hdrplus
diff --git a/src/align.cpp b/src/align.cpp
index 26a81fa..124edde 100644
--- a/src/align.cpp
+++ b/src/align.cpp
@@ -1,7 +1,52 @@
+#include <vector>
 #include <opencv2/opencv.hpp> // all opencv header
 #include "hdrplus/align.h"
+#include "hdrplus/burst.h"
+#include "hdrplus/utility.h"
 
 namespace hdrplus
 {
-    
+
+void align::process( const hdrplus::burst& burst_images, \
+                     std::vector<std::vector<std::vector<std::pair<int, int>>>>& aligements )
+{
+    /*
+    // Build image pyramid
+    std::vector<std::vector<cv::Mat>> grayscale_images_pyramid;
+    grayscale_images_pyramid.resize( burst_images.grayscale_images_pad.size() );
+    for ( int img_idx = 0; img_idx < burst_images.grayscale_images_pad.size(); ++img_idx )
+    {
+        grayscale_images_pyramid[ img_idx ].resize( inv_scale_factors.size() );
+
+        // pyramid image are laied out from coarse to fine
+        // level 0 is the original grayscale image 
+        grayscale_images_pyramid[ img_idx ][ inv_scale_factors.size() - 1 ] = burst_images.grayscale_images_pad[ img_idx];
+
+        // downsample and gaussian blur
+        for ( int i = 1; i < inv_scale_factors.size(); ++i )
+        {
+            int inv_scale_factor_i = inv_scale_factors[ i ];
+            cv::Mat blurred_image = \
+                hdrplus::gaussian_blur( grayscale_images_pyramid[ img_idx ][ i - 1 ], inv_scale_factor_i * 0.5 );
+            
+            // Get around with template
+            cv::Mat downsampled_blurred_image;
+            if ( inv_scale_factor_i == 2 )
+            {
+                hdrplus::downsample_nearest_neighbour<uint16_t, 2>( blurred_image );
+            }
+            else if ( inv_scale_factor_i == 4 )
+            {
+                hdrplus::downsample_nearest_neighbour<uint16_t, 4>( blurred_image );
+            }   
+
+            grayscale_images_pyramid[ img_idx ][ inv_scale_factors.size() - i - 1 ] = downsampled_blurred_image;
+        }
+    }
+
+    cv::GaussianBlur( src_image, dst_image, cv::Size(0, 0), sigma );
+
+    */
+}
+
 } // namespace hdrplus
diff --git a/src/hdrplus_pipeline.cpp b/src/hdrplus_pipeline.cpp
index 60f0e83..fc53dff 100644
--- a/src/hdrplus_pipeline.cpp
+++ b/src/hdrplus_pipeline.cpp
@@ -1,13 +1,32 @@
 #include <cstdio>
+#include <string>
+#include <vector>
+#include <utility> // std::pair
 #include <opencv2/opencv.hpp> // all opencv header
 #include "hdrplus/hdrplus_pipeline.h"
+#include "hdrplus/burst.h"
+#include "hdrplus/align.h"
+#include "hdrplus/merge.h"
+#include "hdrplus/finish.h"
 
 namespace hdrplus
 {
     
-void hdrplus_pipeline::run_pipeline()
+void hdrplus_pipeline::run_pipeline( \
+    const std::string& burst_path, \
+    const std::string& reference_image_path  )
 {
-    printf("Run pipeline\n");
+    // Create burst of images
+    burst burst_images( burst_path, reference_image_path );
+    std::vector<std::vector<std::vector<std::pair<int, int>>>> alignments;
+    
+    // Run align
+    align_module.process( burst_images, alignments );
+
+    // Run merging
+    merge_module.process( burst_images, alignments );
+
+    // Run finishing
 }
 
 } // namespace hdrplus
diff --git a/src/merge.cpp b/src/merge.cpp
index c1195ef..aaa46db 100644
--- a/src/merge.cpp
+++ b/src/merge.cpp
@@ -1,7 +1,15 @@
 #include <opencv2/opencv.hpp> // all opencv header
+#include <vector>
 #include "hdrplus/merge.h"
+#include "hdrplus/burst.h"
 
 namespace hdrplus
 {
+
+void merge::process( const hdrplus::burst& burst_images, \
+                     std::vector<std::vector<std::vector<std::pair<int, int>>>>& aligements )
+{
     
+}
+
 } // namespace hdrplus