Added the "Mask operations on matrices" tutorial (with its sample). Plus modified some other core tutorials.

samples/cpp/tutorial_code/core/discrete_fourier_transform/discrete_fourier_transform.cpp

@@ -18,7 +18,7 @@ void help(char* progName)
 
 int main(int argc, char ** argv)
 {
-    help(argv[0]);
+	help(argv[0]);
 
     const char* filename = argc >=2 ? argv[1] : "lena.jpg";
 

samples/cpp/tutorial_code/core/mat_mask_operations/mat_mask_operations.cpp

@@ -0,0 +1,86 @@
+#include <opencv2/core/core.hpp>
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/imgproc/imgproc.hpp>
+#include <iostream>
+
+using namespace std; 
+using namespace cv;
+
+void help(char* progName)
+{
+    cout << endl 
+        <<  "This program shows how to filter images with mask: the write it yourself and the"
+        << "filter2d way. " << endl
+        <<  "Usage:"                                                                        << endl
+        << progName << " [image_name -- default lena.jpg] [G -- grayscale] "        << endl << endl;
+}
+
+
+void Sharpen(const Mat& myImage,Mat& Result);
+
+int main( int argc, char* argv[])
+{
+    help(argv[0]);
+    const char* filename = argc >=2 ? argv[1] : "lena.jpg";
+
+    Mat I, J, K;
+
+    if (argc >= 3 && !strcmp("G", argv[2]))
+        I = imread( filename, CV_LOAD_IMAGE_GRAYSCALE);
+    else
+        I = imread( filename, CV_LOAD_IMAGE_COLOR);
+
+    namedWindow("Input", CV_WINDOW_AUTOSIZE);
+    namedWindow("Output", CV_WINDOW_AUTOSIZE);
+
+    imshow("Input", I);
+    double t = (double)getTickCount();
+    
+    Sharpen(I, J); 
+    
+    t = ((double)getTickCount() - t)/getTickFrequency();
+    cout << "Hand written function times passed in seconds: " << t << endl;
+
+    imshow("Output", J);
+    cvWaitKey(0);
+
+    Mat kern = (Mat_<char>(3,3) <<  0, -1,  0, 
+                                   -1,  5, -1,
+                                    0, -1,  0);
+    t = (double)getTickCount();
+    filter2D(I, K, I.depth(), kern ); 
+    t = ((double)getTickCount() - t)/getTickFrequency();
+    cout << "Built-in filter2D time passed in seconds:      " << t << endl;
+
+    imshow("Output", K);
+
+    cvWaitKey(0);
+    return 0; 
+}
+void Sharpen(const Mat& myImage,Mat& Result)
+{
+    CV_Assert(myImage.depth() == CV_8U);  // accept only uchar images
+
+    const int nChannels = myImage.channels();
+    Result.create(myImage.size(),myImage.type());
+    
+    for(int j = 1 ; j < myImage.rows-1; ++j)
+    {
+        const uchar* previous = myImage.ptr<uchar>(j - 1);
+        const uchar* current  = myImage.ptr<uchar>(j    );
+        const uchar* next     = myImage.ptr<uchar>(j + 1);
+
+        uchar* output = Result.ptr<uchar>(j);
+
+        for(int i= nChannels;i < nChannels*(myImage.cols-1); ++i)
+        {
+            *output++ = saturate_cast<uchar>(5*current[i] 
+                         -current[i-nChannels] - current[i+nChannels] - previous[i] - next[i]);
+        }
+    }
+
+    Result.row(0).setTo(Scalar(0));
+    Result.row(Result.rows-1).setTo(Scalar(0));
+    Result.col(0).setTo(Scalar(0));
+    Result.col(Result.cols-1).setTo(Scalar(0));
+}