root@raspberrypi:/home/pi# g++ $(pkg-config --cflags opencv) rahul.cpp $(pkg-config --libs opencv) -o imagetest -lopencv_video
/usr/bin/ld: /tmp/ccTM3H9p.o: undefined reference to symbol 'cv::fastFree(void*)'
/usr/bin/ld: note: 'cv::fastFree(void*)' is defined in DSO /usr/lib/libopencv_core.so.2.3 so try adding it to the linker command line
/usr/lib/libopencv_core.so.2.3: could not read symbols: Invalid operation
collect2: ld returned 1 exit status