test.cpp:(.text+0xc0): undefined reference to `cv::imread(std::string const&, int)'

test.cpp:(.text+0xc0): undefined reference to `cv::imread(std::string const&, int)'
test.cpp:(.text+0x11f): undefined reference to `cv::_OutputArray::_OutputArray(cv::Mat&)'

This is a linker issue. Try:

g++ -o test_1 test_1.cpp ` pkg-config opencv --cflags --libs`

after compiling libraries from source, you need to do finally:

sudo ldconfig