clarified docs

samples/cpp/generic_descriptor_match.cpp

@@ -6,6 +6,13 @@
 
 using namespace cv;
 
+void help()
+{
+	printf("Using the surf descriptor for matching keypoints between 2 images\n");
+    printf("Format: \n./generic_descriptor_match [image1] [image2] [algorithm] [XML params]\n");
+    printf("For example: ./generic_descriptor_match scene_l.bmp scene_r.bmp FERN fern_params.xml\n");
+}
+
 IplImage* DrawCorrespondences(IplImage* img1, const vector<KeyPoint>& features1, IplImage* img2,
                               const vector<KeyPoint>& features2, const vector<DMatch>& desc_idx);
 
@@ -13,8 +20,7 @@ int main(int argc, char** argv)
 {
     if (argc != 5)
     {
-        printf("Format: \n./generic_descriptor_match [image1] [image2] [algorithm] [XML params]\n");
-        printf("For example: ./generic_descriptor_match scene_l.bmp scene_r.bmp FERN fern_params.xml\n");
+    	help();
         return 0;
     }