Install OpenCV 4.1.2 on Raspbian Buster
$ chmod +x *.sh
$ ./download-opencv.sh
$ ./install-deps.sh
$ ./build-opencv.sh
$ cd ~/opencv/opencv-4.1.2/build
$ sudo make install
Check you can run test.py
using both python 2 and 3 to verify that OpenCV python bindings were successfully installed
$ wget "https://upload.wikimedia.org/wikipedia/en/7/7d/Lenna_%28test_image%29.png" -O lenna.jpg
$ python2 test.py lenna.jpg
$ python3 test.py lenna.jpg
WARNING: Users of boards with 1GB of memory
Compiling is very memory intensive, you will likely need to increase your swap size. Assuming you have a reasonably large SD card (>16GB to be safe), follow the procedure below to increase your swap size from the default 100MB to 2GB
$ sudo dphys-swapfile swapoff
$ sudo sed -i 's:CONF_SWAPSIZE=.*:CONF_SWAPSIZE=2048:g' /etc/dphys-swapfile
$ sudo reboot
I just compiled latest opencv 4.5.0 debian package for raspberry pi 3/4b buster python 2 and 3, can check out at https://github.com/cyysky/OpenCV-Raspberry-Pi-4-Package-for-Python install follow the readme instruction