[メモ] macOSでOpenCVのビルドがエラーになる件

背景

普段はbrew install opencv や、 pip install opencv-python して使えば良いのだが、設定変更してビルドする必要が生じたので、公式に従ってビルドしてみたら、エラーとなったのでメモ。

• macOS Catalina 10.15.7
• Clang 12.0.0
• OpenCV 4.2.0 のSourceCode

opencvフォルダのあるところで、

bash

mkdir build_opencv
cd build_opencv
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_EXAMPLES=ON ../opencv
make

解決策

結果として以下のように、 BUILD_JPEG_TURBO_DISABLE = ON を追加すれば良い。

cmake -DCMAKE_BUILD_TYPE = Release  -DBUILD_JPEG_TURBO_DISABLE=ON -DBUILD_EXAMPLES = ON ../opencv

原因

3rdparty/libjpeg-turbo のCMakeFile.txtにset(JPEG_LIB_VERSION 62)と定義されているが、#if JPEG_LIB_VERSION >= 70の時しか_jpeg_default_qtablesが定義されない様子。

参考

問題のログ

bash

$ make
[  2%] Built target zlib
[  5%] Built target libjpeg-turbo
[  7%] Built target libtiff
[ 15%] Built target libwebp
[ 18%] Built target libjasper
[ 19%] Built target libpng
[ 26%] Built target IlmImf
[ 28%] Built target ippiw
[ 34%] Built target libprotobuf
[ 34%] Built target quirc
[ 34%] Built target ittnotify
[ 35%] Built target ade
[ 35%] Built target opencv_videoio_plugins
[ 42%] Built target opencv_core
[ 47%] Built target opencv_imgproc
[ 47%] Built target opencv_imgproc
[ 47%] Linking CXX shared library ../../lib/libopencv_imgcodecs.dylib
Undefined symbols for architecture x86_64:
  "_jpeg_default_qtables", referenced from:
      cv::JpegEncoder::write(cv::Mat const&, std::__1::vector<int, std::__1::allocator<int> > const&) in grfmt_jpeg.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [lib/libopencv_imgcodecs.4.2.0.dylib] Error 1
make[1]: *** [modules/imgcodecs/CMakeFiles/opencv_imgcodecs.dir/all] Error 2
make: *** [all] Error 2