2x2 box filter

.gitignore

@@ -47,4 +47,5 @@ external/
 dataset/
 
 # Unit test
-tests/test_bayer_image
+tests/test_bayer_image
+tests/test_utility

CMakeLists.txt

@@ -61,3 +61,9 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/tests )
 add_executable( test_bayer_image 
   tests/test_bayer_image.cpp )
 target_link_libraries( test_bayer_image ${PROJECT_NAME} )
+
+add_executable( test_utility 
+  tests/test_utility.cpp )
+target_link_libraries( test_utility 
+  ${OpenCV_LIBS} 
+  ${PROJECT_NAME} )

include/hdrplus/bayer_image.h

@@ -14,9 +14,11 @@ class bayer_image
         ~bayer_image();
 
         LibRaw libraw_processor;
-        cv::Mat image;
+        cv::Mat raw_image;
+        cv::Mat grayscale_image;
         size_t width;
         size_t height;
+        size_t white_level;
 };
 
 } // namespace hdrplus

include/hdrplus/utility.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <string>
+#include <stdexcept> // std::runtime_error
+#include <opencv2/opencv.hpp> // all opencv header
+// TODO: add openmp support
+
+namespace hdrplus
+{
+
+template <typename T>
+cv::Mat box_filter_2x2( cv::Mat src_image )
+{
+    // https://stackoverflow.com/questions/34042112/opencv-mat-data-member-access
+    const T* src_image_ptr = (T*)src_image.data;
+    int src_height = src_image.size().height;
+    int src_width  = src_image.size().width;
+    int src_step   = src_image.step1();
+
+    if ( src_height % 2 != 0 || src_width % 2 != 0 )
+    {
+        throw std::runtime_error( std::string( __FILE__ ) + "::" + __func__ + " source image need to have size multiplier of 2\n" );
+    }
+
+    cv::Mat dst_image( src_height / 2, src_width / 2, src_image.type() );
+    T* dst_image_ptr = (T*)dst_image.data;
+    //int dst_height = dst_image.size().height;
+    //int dst_width  = dst_image.size().width;
+    int dst_step = dst_image.step1();
+
+    // -03 should be enough to optimize below code
+    for ( int row_i = 0; row_i < src_height; row_i += 2 )
+    {
+        for ( int col_i = 0; col_i < src_width; col_i += 2 )
+        {
+            T box_sum = src_image_ptr[ ( row_i + 0 ) * src_step + col_i + 0 ] + \
+                        src_image_ptr[ ( row_i + 0 ) * src_step + col_i + 1 ] + \
+                        src_image_ptr[ ( row_i + 1 ) * src_step + col_i + 0 ] + \
+                        src_image_ptr[ ( row_i + 1 ) * src_step + col_i + 1 ];
+            T box_avg = ( box_sum + T(3) ) / 4; // take ceiling
+            dst_image_ptr[ ( row_i / 2 ) * dst_step + ( col_i / 2 ) ] = box_avg;
+        }
+    }
+
+    // cv::Mat internally use reference count. Will not copy by value here
+    return dst_image;
+}
+
+} // namespace hdrplus

src/bayer_image.cpp

@@ -1,8 +1,10 @@
 #include <string>
+#include <cstdio>
+#include <stdexcept> // std::runtime_error
 #include <opencv2/opencv.hpp> // all opencv header
 #include <libraw/libraw.h>
 #include "hdrplus/bayer_image.h"
-
+#include "hdrplus/utility.h" // box_filter_2x2
 namespace hdrplus
 {
 
@@ -25,10 +27,20 @@ bayer_image::bayer_image( const std::string& bayer_image_path )
     // Get image basic info
     width = size_t( libraw_processor.imgdata.rawdata.sizes.raw_width );
     height = size_t( libraw_processor.imgdata.rawdata.sizes.raw_height );
+    white_level = size_t( libraw_processor.imgdata.rawdata.color.maximum );
+
+    #ifndef NDEBUG
+    printf("%s::%s read bayer image %d with width %zu height %zu", \
+        __FILE__, __func__, bayer_image_path.c_str(), width, height );
+    #endif
 
     // Create CV mat
     // https://answers.opencv.org/question/105972/de-bayering-a-cr2-image/
-    image = cv::Mat( width, height, CV_16U, libraw_processor.imgdata.rawdata.raw_image );
+    // https://www.libraw.org/node/2141
+    raw_image = cv::Mat( width, height, CV_16U, libraw_processor.imgdata.rawdata.raw_image );
+
+    // 2x2 box filter
+    grayscale_image = box_filter_2x2<uint16_t>( raw_image );
 }
 
 bayer_image::~bayer_image()

tests/test_utility.cpp

@@ -0,0 +1,49 @@
+#include <cstdio>
+#include <vector>
+#include <opencv2/opencv.hpp>
+#include "hdrplus/utility.h"
+
+template< typename T >
+void print_cvmat( cv::Mat image )
+{
+    int height = image.size().height;
+    int width = image.size().width;
+
+    for ( int row_i = 0; row_i < height; ++row_i )
+    {
+        for ( int col_i = 0; col_i < width; ++col_i )
+        {
+            printf("%2.d ", int( image.at<T>( row_i, col_i ) ) );
+        }
+        printf("\n");
+    }
+}
+
+void test_box_filter_2x2()
+{
+    // Intialize input data
+    int src_width = 10;
+    int src_height = 6;
+    std::vector<uint16_t> src_data( src_width, src_height );
+
+    for ( int i = 0; i < src_width * src_height; ++i )
+    {
+        src_data[ i ] = i+1;
+    }
+
+    // Create input cv::mat
+    cv::Mat src_image( src_height, src_width, CV_16U, src_data.data() );
+
+    printf("src cv::Mat is \n");
+    print_cvmat<uint16_t>( src_image );
+
+    cv::Mat dst_image = hdrplus::box_filter_2x2<uint16_t>( src_image );
+
+    printf("dst cv::Mat is \n");
+    print_cvmat<uint16_t>( dst_image );
+}
+
+int main()
+{
+    test_box_filter_2x2();
+}