Opencv Installation

sudo apt install build-essential cmake unzip pkg-config libjpeg-dev libpng-dev libtiff-dev libavcodec-dev libavformat-dev libswscale-dev libv4l-dev libxvidcore-dev libx264-dev libgtk-3-dev libatlas-base-dev gfortran python3-dev

cd ~
wget -O opencv.zip https://github.com/opencv/opencv/archive/4.0.1.zip
wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/4.0.1.zip

unzip opencv.zip
unzip opencv_contrib.zip

mv opencv-4.0.1 opencv
mv opencv_contrib-4.0.1 opencv_contrib

cd ~/opencv
mkdir build
cd build

cmake -D CMAKE_BUILD_TYPE=RELEASE \
	-D CMAKE_INSTALL_PREFIX=/usr/local \
	-D INSTALL_PYTHON_EXAMPLES=ON \
	-D INSTALL_C_EXAMPLES=OFF \
	-D OPENCV_ENABLE_NONFREE=ON \
	-D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib/modules \
	-D PYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)") \
	-D BUILD_opencv_python3=yes \
	-D PYTHON_INCLUDE_DIR=$(python -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())")  \
	-D PYTHON_LIBRARY=$(python -c "import distutils.sysconfig as sysconfig; print(sysconfig.get_config_var('LIBDIR'))") \
	-D BUILD_EXAMPLES=ON ..

make -j4

sudo make install
sudo ldconfig

How to install OpenCV 4 on Ubuntu