Automatically skip images with no detections

examples/dnn_instance_segmentation_ex.cpp

@@ -127,10 +127,13 @@ int main(int argc, char** argv) try
         // Show the input image on the left, and the predicted RGB labels on the right.
         win.set_image(join_rows(input_image, rgb_label_image));
 
+        if (!instances.empty())
+        {
             cout << file.name() << " - hit enter to process the next image";
             cin.get();
         }
     }
+}
 catch(std::exception& e)
 {
     cout << e.what() << endl;