Introduction

This document describes how to build a simple opencv project in macos. It is done all in command lines.

install the minimum set of xcode

xcode-select --install

install python3

This is needed to run opencv4.

brew install python3
brew switch python <the version you have installed>

test if python3 works

python3

install opencv

brew install opencv@2

pkg-config

check if $PKG_CONFIG is configured:

echo $PKG_CONFIG

If not set it

export PKG_CONFIG=/usr/local/lib/pkgconfig/

This is a tool to setup the path parameters when using command line to build.

setup pkg-config for opencv@2

ln -s /usr/local/opt/opencv@2/lib/pkgconfig/opencv.pc $PKG_CONFIG

Test to see if pkg-config return parameters for opencv:

pkg-config --cflags --libs opencv

compile the project

g++ $(pkg-config --cflags --libs opencv)  demo.cpp

ld: symbol(s) not found for architecture x86_64

There are two implementations of the standard C++ library available on OS X:
libstdc++ and libc++. They are not binary compatible and libMLi3 requires
libstdc++.  On 10.8 and earlier libstdc++ is chosen by default, on 10.9 libc++
is chosen by default. To ensure compatibility with libMLi3, we need to choose
libstdc++ manually.  To do this, add -stdlib=libstdc++ to the linking command.