Step 1 – Updating Ubuntu

$ sudo apt-get update
$ sudo apt-get upgrade

Step 2 – Install dependencies

$ sudo apt-get install build-essential cmake git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev
$ sudo apt-get install python3.5-dev python3-numpy libtbb2 libtbb-dev
$ sudo apt-get install libjpeg-dev libpng-dev libtiff5-dev libjasper-dev libdc1394-22-dev libeigen3-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev sphinx-common libtbb-dev yasm libfaac-dev libopencore-amrnb-dev libopencore-amrwb-dev libopenexr-dev libgstreamer-plugins-base1.0-dev libavutil-dev libavfilter-dev libavresample-dev
 

Step 3 –  Get OpenCV

$ sudo -s
$ cd /opt
/opt$ git clone https://github.com/Itseez/opencv.git
/opt$ git clone https://github.com/Itseez/opencv_contrib.git

Step 4 – build and install OpenCV

/opt$ cd opencv
/opt/opencv$ mkdir release
/opt/opencv$ cd release
/opt/opencv/release$ cmake -D BUILD_TIFF=ON -D WITH_CUDA=OFF -D ENABLE_AVX=OFF -D WITH_OPENGL=OFF -D WITH_OPENCL=OFF -D WITH_IPP=OFF -D WITH_TBB=ON -D BUILD_TBB=ON -D WITH_EIGEN=OFF -D WITH_V4L=OFF -D WITH_VTK=OFF -D BUILD_TESTS=OFF -D BUILD_PERF_TESTS=OFF -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D OPENCV_EXTRA_MODULES_PATH=/opt/opencv_contrib/modules /opt/opencv/
/opt/opencv/release$ make -j4
/opt/opencv/release$ make install
/opt/opencv/release$ ldconfig
/opt/opencv/release$ exit
/opt/opencv/release$ cd ~
 

Now to check if OpenCV is installed on a machine, run the following commands

$ pkg-config --modversion opencv
4.0.0

步驟3，sudo -s從當前使用者切換到root使用者下，然後將Opencv的原始碼下載到了/opt目錄下。若未在root使用者下操作步驟3，OpenCV的程式碼可以下載任何自定義的目錄，那麼在執行步驟4時，cmake時需要修改路徑，以及安裝時採用sudo make install和sudo ldconfig。例如，opencv程式碼下載到/mnt/tools/路徑時

/mnt/tools/opencv/release$ cmake -D BUILD_TIFF=ON -D WITH_CUDA=OFF -D ENABLE_AVX=OFF -D WITH_OPENGL=OFF -D WITH_OPENCL=OFF -D WITH_IPP=OFF -D WITH_TBB=ON -D BUILD_TBB=ON -D WITH_EIGEN=OFF -D WITH_V4L=OFF -D WITH_VTK=OFF -D BUILD_TESTS=OFF -D BUILD_PERF_TESTS=OFF -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D OPENCV_EXTRA_MODULES_PATH=/mnt/tools/opencv_contrib/modules /mnt/tools/opencv/