Tutorial Discrete Fourier Transform

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

@@ -8,45 +8,58 @@
 using namespace cv;
 using namespace std;
 
-static void help(char* progName)
+static void help(void)
 {
     cout << endl
         <<  "This program demonstrated the use of the discrete Fourier transform (DFT). " << endl
         <<  "The dft of an image is taken and it's power spectrum is displayed."          << endl
         <<  "Usage:"                                                                      << endl
-        << progName << " [image_name -- default ../data/lena.jpg] "               << endl << endl;
+        <<  "./discrete_fourier_transform [image_name -- default ../data/lena.jpg]"       << endl;
 }
 
 int main(int argc, char ** argv)
 {
-    help(argv[0]);
+    help();
 
     const char* filename = argc >=2 ? argv[1] : "../data/lena.jpg";
 
     Mat I = imread(filename, IMREAD_GRAYSCALE);
-    if( I.empty())
+    if( I.empty()){
+        cout << "Error opening image" << endl;
         return -1;
+    }
 
+//! [expand]
     Mat padded;                            //expand input image to optimal size
     int m = getOptimalDFTSize( I.rows );
     int n = getOptimalDFTSize( I.cols ); // on the border add zero values
     copyMakeBorder(I, padded, 0, m - I.rows, 0, n - I.cols, BORDER_CONSTANT, Scalar::all(0));
+//! [expand]
 
+//! [complex_and_real]
     Mat planes[] = {Mat_<float>(padded), Mat::zeros(padded.size(), CV_32F)};
     Mat complexI;
     merge(planes, 2, complexI);         // Add to the expanded another plane with zeros
+//! [complex_and_real]
 
+//! [dft]
     dft(complexI, complexI);            // this way the result may fit in the source matrix
+//! [dft]
 
     // compute the magnitude and switch to logarithmic scale
     // => log(1 + sqrt(Re(DFT(I))^2 + Im(DFT(I))^2))
+//! [magnitude]
     split(complexI, planes);                   // planes[0] = Re(DFT(I), planes[1] = Im(DFT(I))
     magnitude(planes[0], planes[1], planes[0]);// planes[0] = magnitude
     Mat magI = planes[0];
+//! [magnitude]
 
+//! [log]
     magI += Scalar::all(1);                    // switch to logarithmic scale
     log(magI, magI);
+//! [log]
 
+//! [crop_rearrange]
     // crop the spectrum, if it has an odd number of rows or columns
     magI = magI(Rect(0, 0, magI.cols & -2, magI.rows & -2));
 
@@ -67,9 +80,12 @@ int main(int argc, char ** argv)
     q1.copyTo(tmp);                    // swap quadrant (Top-Right with Bottom-Left)
     q2.copyTo(q1);
     tmp.copyTo(q2);
+//! [crop_rearrange]
 
+//! [normalize]
     normalize(magI, magI, 0, 1, NORM_MINMAX); // Transform the matrix with float values into a
                                             // viewable image form (float between values 0 and 1).
+//! [normalize]
 
     imshow("Input Image"       , I   );    // Show the result
     imshow("spectrum magnitude", magI);