exell@exell-MS-7A63:~$ git clone https://github.com/openalpr/openalpr.git
Cloning into 'openalpr'...
remote: Enumerating objects: 8831, done.
remote: Total 8831 (delta 0), reused 0 (delta 0), pack-reused 8831
Receiving objects: 100% (8831/8831), 5.59 MiB | 3.66 MiB/s, done.
Resolving deltas: 100% (6103/6103), done.
exell@exell-MS-7A63:~$ cd openalpr/src
exell@exell-MS-7A63:~/openalpr/src$ mkdir build
exell@exell-MS-7A63:~/openalpr/src$ cd build
exell@exell-MS-7A63:~/openalpr/src/build$ cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr -DCMAKE_INSTALL_SYSCONFDIR:PATH=/etc ..
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Tesseract
-- Found OpenCV: /usr/local (found version "4.0.1")
-- Found CURL: /usr/lib/x86_64-linux-gnu/libcurl.so (found version "7.58.0")
-- Found log4cplus
-- Found JNI: /usr/lib/jvm/default-java/lib/libjawt.so
-- Configuring done
-- Generating done
-- Build files have been written to: /home/exell/openalpr/src/build
exell@exell-MS-7A63:~/openalpr/src/build$ make
Scanning dependencies of target support
[  1%] Building CXX object openalpr/support/CMakeFiles/support.dir/filesystem.cpp.o
[  1%] Building CXX object openalpr/support/CMakeFiles/support.dir/timing.cpp.o
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[  7%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/mimics_pcre.cc.o
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[ 18%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/util/hash.cc.o
[ 18%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/util/stringprintf.cc.o
[ 19%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/util/rune.cc.o
[ 20%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/util/strutil.cc.o
[ 20%] Building CXX object openalpr/support/CMakeFiles/support.dir/re2/util/valgrind.cc.o
[ 21%] Linking CXX static library libsupport.a
[ 21%] Built target support
Scanning dependencies of target video
[ 22%] Building CXX object video/CMakeFiles/video.dir/videobuffer.cpp.o
[ 23%] Linking CXX static library libvideo.a
[ 23%] Built target video
Scanning dependencies of target openalpr
[ 24%] Building CXX object openalpr/CMakeFiles/openalpr.dir/alpr.cpp.o
[ 24%] Building CXX object openalpr/CMakeFiles/openalpr.dir/alpr_impl.cpp.o
/home/exell/openalpr/src/openalpr/alpr_impl.cpp: In member function ‘alpr::AlprFullDetails alpr::AlprImpl::recognizeFullDetails(cv::Mat, std::vector<cv::Rect_<int> >)’:
/home/exell/openalpr/src/openalpr/alpr_impl.cpp:118:31: error: ‘CV_BGR2GRAY’ was not declared in this scope
       cvtColor( img, grayImg, CV_BGR2GRAY );
                               ^~~~~~~~~~~
openalpr/CMakeFiles/openalpr.dir/build.make:86: recipe for target 'openalpr/CMakeFiles/openalpr.dir/alpr_impl.cpp.o' failed
make[2]: *** [openalpr/CMakeFiles/openalpr.dir/alpr_impl.cpp.o] Error 1
CMakeFiles/Makefile2:623: recipe for target 'openalpr/CMakeFiles/openalpr.dir/all' failed
make[1]: *** [openalpr/CMakeFiles/openalpr.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2