Install OpenCV 4 on your Raspberry Pi, 2018-09-26
Installing OpenCV 3.4.3 on Raspberry Pi 3 Model B+, 2018-09-05
Installing OpenCV on Raspberry Pi 3 B, 2018-04-27
Raspbian Stretch: Install OpenCV 3 + Python on your Raspberry Pi, 2017-09-04
Install guide: Raspberry Pi 3 + Raspbian Jessie + OpenCV 3, 2016-04-18
How to Install OpenCV 3.4.0 with Python 3 on Raspberry Pi 3, 2018-03-03
github.com/jabelone/OpenCV-for-Pi, A pre-compiled binary of OpenCV 3.1.0 for the Raspberry Pi