I’m getting linker errors on code that uses imread, imshow, and the Mat object constructor and destructor.
I’m on Linux Mint version 20.3, my OpenCV version is 4.2, and my g++ version is 9.4.
This this the output from linking the libraries one by one:
g++ -L/usr/lib/x86_64-linux-gnu -lopencv_core -lopencv_imgcodecs -lopencv_highgui main.o visualizeBitPallette.o -o visualizeBitPallette
/usr/bin/ld: main.o: in function `grayscaleRedTest()':
main.cpp:(.text+0x449): undefined reference to `cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
/usr/bin/ld: main.cpp:(.text+0x509): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
/usr/bin/ld: main.cpp:(.text+0x542): undefined reference to `cv::Mat::~Mat()'
/usr/bin/ld: main.cpp:(.text+0x551): undefined reference to `cv::Mat::~Mat()'
/usr/bin/ld: main.cpp:(.text+0x60a): undefined reference to `cv::Mat::~Mat()'
/usr/bin/ld: main.cpp:(.text+0x622): undefined reference to `cv::Mat::~Mat()'
/usr/bin/ld: visualizeBitPallette.o: in function `getPreviewImage(std::vector<BitColor, std::allocator<BitColor> >, unsigned int, cv::Mat&)':
visualizeBitPallette.cpp:(.text+0x3a4): undefined reference to `cv::Mat::Mat(int, int, int)'
/usr/bin/ld: visualizeBitPallette.cpp:(.text+0x4d5): undefined reference to `cv::Mat::~Mat()'
collect2: error: ld returned 1 exit status
make: *** [Makefile:9: visualizeBitPallette] Error 1
Running “g++ pkg-config opencv4 --cflags --libs main.o visualizeBitPallette.o -o visualizeBitPallette” gives exactly the same output, as does linking with “pkg-config opencv4 --cflags --libs-L/usr/lib/x86_64-linux-gnu”.
The output from “pkg-config opencv4 --cflags --libs”:
-I/usr/include/opencv4/opencv -I/usr/include/opencv4 -lopencv_stitching -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_dnn_objdetect -lopencv_dnn_superres -lopencv_dpm -lopencv_highgui -lopencv_face -lopencv_freetype -lopencv_fuzzy -lopencv_hdf -lopencv_hfs -lopencv_img_hash -lopencv_line_descriptor -lopencv_quality -lopencv_reg -lopencv_rgbd -lopencv_saliency -lopencv_shape -lopencv_stereo -lopencv_structured_light -lopencv_phase_unwrapping -lopencv_superres -lopencv_optflow -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_dnn -lopencv_plot -lopencv_ml -lopencv_videostab -lopencv_videoio -lopencv_viz -lopencv_ximgproc -lopencv_video -lopencv_xobjdetect -lopencv_objdetect -lopencv_calib3d -lopencv_imgcodecs -lopencv_features2d -lopencv_flann -lopencv_xphoto -lopencv_photo -lopencv_imgproc -lopencv_core
These are all of the libraries in the directory specified:
(cd /usr/lib/x86_64-linux-gnu && ls -1 libopencv*.so)
libopencv_aruco.so
libopencv_bgsegm.so
libopencv_bioinspired.so
libopencv_calib3d.so
libopencv_ccalib.so
libopencv_core.so
libopencv_datasets.so
libopencv_dnn_objdetect.so
libopencv_dnn.so
libopencv_dnn_superres.so
libopencv_dpm.so
libopencv_face.so
libopencv_features2d.so
libopencv_flann.so
libopencv_freetype.so
libopencv_fuzzy.so
libopencv_hdf.so
libopencv_hfs.so
libopencv_highgui.so
libopencv_imgcodecs.so
libopencv_img_hash.so
libopencv_imgproc.so
libopencv_line_descriptor.so
libopencv_ml.so
libopencv_objdetect.so
libopencv_optflow.so
libopencv_phase_unwrapping.so
libopencv_photo.so
libopencv_plot.so
libopencv_quality.so
libopencv_reg.so
libopencv_rgbd.so
libopencv_saliency.so
libopencv_shape.so
libopencv_stereo.so
libopencv_stitching.so
libopencv_structured_light.so
libopencv_superres.so
libopencv_surface_matching.so
libopencv_text.so
libopencv_tracking.so
libopencv_videoio.so
libopencv_video.so
libopencv_videostab.so
libopencv_viz.so
libopencv_ximgproc.so
libopencv_xobjdetect.so
libopencv_xphoto.so
My included OpenCV headers:
#include <opencv2/core/mat.hpp>
#include <opencv2/imgcodecs.hpp> // imread
#include <opencv2/highgui.hpp> // imshow
How can I successfully link this code against the libraries I need?