avoid Ptr<> == NULL checks

samples/cpp/detect_blob.cpp

@@ -178,7 +178,7 @@ int main(int argc, char *argv[])
             vector<Rect>  zone;
             vector<vector <Point> >  region;
             Mat     desc, result(img.rows, img.cols, CV_8UC3);
-            if (b.dynamicCast<SimpleBlobDetector>() != NULL)
+            if (b.dynamicCast<SimpleBlobDetector>().get())
             {
                 Ptr<SimpleBlobDetector> sbd = b.dynamicCast<SimpleBlobDetector>();
                 sbd->detect(img, keyImg, Mat());

samples/cpp/detect_mser.cpp

@@ -500,7 +500,7 @@ int main(int argc, char *argv[])
             vector<vector <Point> > region;
             Mat desc;
 
-            if (b.dynamicCast<MSER>() != NULL)
+            if (b.dynamicCast<MSER>().get())
             {
                 Ptr<MSER> sbd = b.dynamicCast<MSER>();
                 sbd->detectRegions(img, region, zone);