Install OpenCV#

We use OpenCV for real-time computer vision. Official download page: link

Install OpenCV (Ubuntu)#

sudo apt install libopencv-dev

Install OpenCV 3 (With contrib and Python 3 support)#

Adapted from this post.

Upgrade any pre-installed packages:
```
sudo apt update
sudo apt upgrade
```

Install developer tools used to compile OpenCV 3.0:

sudo apt install build-essential cmake git pkg-config

Install libraries and packages used to read various image and video formats from disk:

sudo apt install libjpeg8-dev libtiff-dev libjasper-dev libpng12-dev
sudo apt install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev

Install GTK so we can use OpenCV’s GUI features:
```
sudo apt install libgtk2.0-dev
```
Install packages that are used to optimize various functions inside OpenCV, such as matrix operations:
```
sudo apt install libatlas-base-dev gfortran
```
Install the Python 3.4+ headers and development files:
```
sudo apt install python3.4-dev
```
Install pip
Install Numpy
```
sudo -H pip install numpy
```

Download OpenCV main repo

mkdir -p repos
cd repos
git clone https://github.com/Itseez/opencv.git
cd opencv
git checkout 3.0.0

Download OpenCV contrib repo

cd ..
git clone https://github.com/Itseez/opencv_contrib.git
cd opencv_contrib
git checkout 3.0.0

Configure OpenCV main repo

cd ../opencv
mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=RELEASE \
      -D CMAKE_INSTALL_PREFIX=/usr/local \
      -D INSTALL_C_EXAMPLES=ON \
      -D INSTALL_PYTHON_EXAMPLES=ON \
      -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib/modules \
      -D BUILD_EXAMPLES=ON ..

The last step can also be done by hand using ccmake.

Compile and install (This will probably take a long time, use the -j flag to speed up things using multithreaded compilation) bash make -j$(nproc) # compile sudo make install; sudo ldconfig; cd # install and go home

Install OpenCV 3 (With contrib, Python 3 support and fix for SVM_load)#

OpenCV 3 has no method to load the SVM unless the specific commit where this was fixed is used (see this and this for related info).

To install OpenCV 3 with support for SVM loading, follow the previous steps, executing the following commands after step 10:

cd ../opencv
git checkout 37cbcf024c2b4160648299887a7c28d7cf28b1d3
cd ../opencv_contrib
git checkout 5409d5ad560523c85c6796cc5a009347072d883c

Then, continue with the previous guide, executing steps 11 and 12.

Install OpenCV 3 (With Python 3 support, CUDA 8 support, no NVIDIA driver installed)#

To install OpenCV 3 with Python 3 support and CUDA 8 support (but no NVIDIA driver installed), follow the steps 1-9 of Install OpenCV 3 (With contrib and Python 3 support). Then, perform these steps:

Patch the 3.0.0 branch to fix the issue with removed GraphCut in CUDA 8

git format-patch -1 10896129b39655e19e4e7c529153cb5c2191a1db
git am < 0001-GraphCut-deprecated-in-CUDA-7.5-and-removed-in-8.0.patch

Configure OpenCV main repo with CUDA and libcuda.so path

mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=RELEASE \
      -D CMAKE_INSTALL_PREFIX=/usr/local \
      -D INSTALL_C_EXAMPLES=ON \
      -D INSTALL_PYTHON_EXAMPLES=ON \
      -D BUILD_EXAMPLES=ON \
      -D WITH_CUDA=ON \
      -D BUILD_CUDA_STUBS=ON \
      -D CMAKE_LIBRARY_PATH=/usr/local/cuda/lib64/stubs..

The last step can also be done by hand using ccmake.

Compile and install (this will probably take a long time, use the -j flag to speed up things using multithreaded compilation)
```
make -j$(nproc)  # compile
sudo make install; sudo ldconfig; cd  # install and go home
```