pybind11_opencv_numpy

Binding between cv::Mat and np.array. And a small code example of how it work. the code work for OpenCV 2.4, OpenCV 3+ and OpenCV 4+

The code in this repository create a simple binding, function in c++ are implemented in example.cpp file and the script that use them is test.py.

/project folder
├── build
├── example
│   ├── exemple.so                               # generate with cmake
│   └── example.cpython-36m-x86_64-linux-gnu.so  # generate with setup.py (the name will depends of the python version use)
├── CMakeLists.txt
├── setup.py
├── ndarray_converter.cpp  # Effective implementation of the binding
├── ndarray_converter.h    # Header for binding functions
└── ...

Generation with cmake/make

Note : This method support opencv 2.4, opencv 3 and opencv 4.

We use vcpkg to install pybind11 library

./vcpkg install pybind11

Compile

mkdir build
cd build
# configure make with vcpkg toolchain
cmake .. -DCMAKE_TOOLCHAIN_FILE=${VCPKG_DIR}/scripts/buildsystems/vcpkg.cmake
# generate the example.so library
make
# move example.so library in example folder
make install

Generation with setup.py

install pybind11

pip3 install pybind11

Compile

OpenCV 2.4+, OpenCV 3+

python3 setup.py build

OpenCV 4

In OpenCV 4, there a extra folder level for headers (ex: opencv4/opencv2/core/core.hpp). To be able to compile with setup.py we need a extra command to indicate header location.

python3 setup.py build_ext --include-dirs "/usr/local/include/opencv4"
python3 setup.py build

Install

python3 setup.py install

or

mv build/lib.linux-x86_64-3.5/example/example.cpython-36m-x86_64-linux-gnu.so example/example.cpython-36m-x86_64-linux-gnu.so