Step #1: Expand filesystem and reclaim space For the remainder of this tutorial I’ll be making the following assumptions: You are working with a brand new, fresh install of Raspbian Stretch . This is not the first time you have installed OpenCV on the Raspberry Pi using Python virtual environments. If it is, please get your feet wet using one of my introductory OpenCV install guides . You are comfortable with the command line and Unix environments. You know how to debug CMake output for common errors (Python virtual environment not found, missing Python libraries, etc.). Again, this tutorial is an advanced guide so I’ll presenting the commands and only providing an explanation if it is pertinent — by and large, you should know what these commands do before you execute them. The first step is to run, raspi - config and expand your filesystem: Optimizing OpenCV on the Raspberry Pi Shell 1 $ sudo rasp...