Compile OpenCV4

Since OpenCV4 does not generata .pc file by default, we need to compile it from source and turn on the OPENCV_GENERATE_PKGCONFIG option if other programs need the pkg-config file.

Another problem I encountered is a number of errors similar to undefined reference to TIFFReadRGBAStrip@LIBTIFF_4.0. To solve that, the BUILD_TIFF option needs to be turned on.

And following is the script for compilation and installation.

wget https://github.com/opencv/opencv/archive/4.1.0.zip unzip opencv-4.1.0.zip cd opencv-4.1.0 mkdir build && cd build cmake -D CMAKE_BUILD_TYPE=Release -D OPENCV_GENERATE_PKGCONFIG=YES -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_TIFF=ON sudo make -j`nproc` sudo make install