undefined reference to cv::imread(cv::String const&, int)

.build_release/lib/libcaffe-nv.so: undefined reference to cv::imread(cv::String const&, int)' 

.build_release/lib/libcaffe-nv.so: undefined reference tocv::imencode(cv::String const&, cv::_InputArray const&, 
std::vector >&, std::vector > const&)'
.build_release/lib/libcaffe-nv.so: undefined reference to `cv::imdecode(cv::_InputArray const&, int)'
collect2: error: ld returned 1 exit status
make: *** [.build_release/tools/upgrade_net_proto_text.bin] Error 1

[Solution]
change Makefile:
LIBRARIES += glog gflags protobuf leveldb snappy \
lmdb boost_system hdf5_hl hdf5 m \
opencv_core opencv_highgui opencv_imgproc
add :opencv_imgcodecs solve my problem