find and drawContours doc

samples/cpp/contours2.cpp

 #include "cv.h"
 #include "highgui.h"
 #include <math.h>
+#include <iostream>
 
 using namespace cv;
 
+void help()
+{
+	cout
+	<< "This program illustrates the use of findContours and drawContours\n"
+	<< "The original image is put up along with the image of drawn contours\n"
+	<< "Usage:\n"
+	<< "./contours2\n"
+	<< "\nA trackbar is put up which controls the contour level from -3 to 3\n"
+	<< endl;
+}
+
 const int w = 500;
 int levels = 3;
 
@@ -20,10 +32,15 @@ void on_trackbar(int, void*)
     imshow("contours", cnt_img);
 }
 
-int main( int, char** )
+int main( int argc, char** argv)
 {
     Mat img = Mat::zeros(w, w, CV_8UC1);
-
+    if(argc > 1)
+    {
+    	help();
+    	return -1;
+    }
+    //Draw 6 faces
     for( int i = 0; i < 6; i++ )
     {
         int dx = (i%2)*250 - 30;
@@ -55,10 +72,10 @@ int main( int, char** )
         ellipse( img, Point(dx+27, dy+100), Size(20,35), 0, 0, 360, white, -1, 8, 0 );
         ellipse( img, Point(dx+273, dy+100), Size(20,35), 0, 0, 360, white, -1, 8, 0 );
     }
-
+    //show the faces
     namedWindow( "image", 1 );
     imshow( "image", img );
-
+    //Extract the contours so that
     vector<vector<Point> > contours0;
     findContours( img, contours0, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE);