--- modules/video_filter/opencv_example.cpp.orig	2015-10-19 13:07:12.000000000 +0200
+++ modules/video_filter/opencv_example.cpp	2015-10-19 13:10:05.000000000 +0200
@@ -42,6 +42,7 @@
 #include <opencv2/core/core_c.h>
 #include <opencv2/core/core.hpp>
 #include <opencv2/objdetect/objdetect.hpp>
+#include <opencv2/highgui/highgui.hpp>
 
 /*****************************************************************************
  * filter_sys_t : filter descriptor