Ubuntu18.04安装OpenCV4.2.0（不包含Python）

之前写的项目安装教程节选Opencv部分。当时用的英文。有时间我再转中文。

• Install dependant envs

$ sudo apt-get install \
    build-essential \
    libgtk2.0-dev \
    libgtk-3-dev \
    libavcodec-dev \
    libavformat-dev \
    libjpeg-dev \
    libswscale-dev \
    libtiff5-dev

• unzip opencv and cd in it, then make build folder, build and cmake.

$ sudo tar -zxvf ./opencv-4.2.0.tar.gz
$ cd opencv-4.2.0/
$ mkdir build
$ cd build/
$ cmake -D CMAKE_BUILD_TYPE=Release -D OPENCV_GENERATE_PKGCONFIG=YES -D CMAKE_INSTALL_PREFIX=/usr/local/opencv4 ..

Notes:

-D OPENCV_GENERATE_PKGCONFIG=YES：set YES to generate opencv4.pc，support pkg-config

-D CMAKE_INSTALL_PREFIX=/usr/local/opencv4：Specify installation directory.

• Make and install

$ sudo make -j`nproc`
$ sudo make install -j`nproc`

• add /usr/local/opencv4/lib/pkgconfig/ to PKG_CONFIG_PATH

$ sudo find / -iname opencv4.pc
/home/dreamdeck/Downloads/opencv-4.2.0/build/unix-install/opencv4.pc
/usr/local/opencv4/lib/pkgconfig/opencv4.pc
$ sudo gedit ~/.bashrc

export PKG_CONFIG_PATH=/usr/local/opencv4/lib/pkgconfig:$PKG_CONFIG_PATH

$source ~/.bashrc
$ pkg-config --libs opencv4
-L/usr/local/opencv4/lib -lopencv_dnn -lopencv_gapi -lopencv_highgui -lopencv_ml -lopencv_objdetect -lopencv_photo -lopencv_stitching -lopencv_video -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_videoio -lopencv_imgcodecs -lopencv_imgproc -lopencv_core

If it returns error when pkg-config, please check out ~/.bashrc and source it. If the error is also remained, please reboot computer.

• Set opencv4.conf

if don’t set it, may get this error

error while loading shared libraries: libopencv_imgcodecs.so.4.2: cannot open shared object file: No such file or directory

Then follow the steps:

$ cd /etc/ld.so.conf.d
$ sudo touch opencv4.conf
$ sudo gedit opencv4.conf

Write the following contant to opencv4.conf

/usr/local/opencv4/lib

Activate

sudo ldconfig

Reboot vscode.