Yes, I realized that.
I have also tried doing:
./opencv_1 lena.jpg
and now get this error:
Abort trap (core dumped)
Here is the gdb back trace debugging:
GNU gdb (GDB) 12.1 [GDB v12.1 for FreeBSD]
Reading symbols from /home/user/OpenCV_1/opencv_1...
[New LWP 128661]
warning: Unexpected size of section `.reg-xstate/128661' in core file.
Core was generated by `./opencv_1 lena.jpg'.
Program terminated with signal SIGABRT, Aborted.
Sent by thr_kill() from pid 3967 and user 1001.
warning: Unexpected size of section `.reg-xstate/128661' in core file.
#0 0x0000000804cb433a in thr_kill () from /lib/libc.so.7
(gdb) bt
#0 0x0000000804cb433a in thr_kill () at /lib/libc.so.7
#1 0x0000000804c2cc74 in raise () at /lib/libc.so.7
#2 0x0000000804cde109 in abort () at /lib/libc.so.7
#3 0x0000000800febe69 in () at /lib/libcxxrt.so.1
#4 0x00000008041e98f5 in cv::error(cv::Exception const&) () at /usr/local/lib/libopencv_core.so.405
#5 0x00000008041e91a2 in cv::error(int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, char const*, char const*, int) ()
at /usr/local/lib/libopencv_core.so.405
#6 0x0000000800db7417 in cv::namedWindow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int) () at /usr/local/lib/libopencv_highgui.so.405
#7 0x00000000002027a9 in main(int, char**) (argc=2, argv=0x7fffffffe478) at opencv_1.cpp:28
Trace shows exception was raised in cv::namedWindow()
I think OpenCV have some trouble to display the image, like literally. Because it could be that OpenCV does not know how to access the window/desktop server to display the image on the KDE desktop environment I am using.
Does OpenCV works out of the box for FreeBSD 13.1 using KDE5 plasma desktop environment, does it need like GTK or QT to work?