OpenCV on Fedora 24

The standard install of opencv appears to be broken on Fedora 24 - because (when loading an image) it requires libavcodec.so.53 whereas up-to-date ffmpeg-devel has an apparently useless libavcodec.so.57.

So, building from source appears to be the way to go (particularly since Fedora 24 has opencv ~2.4.12, rather than opencv ~3.0.0.

Building OpenCV from source

This makes use of these instructions.

Clone OpenCV from GitHub

git clone https://github.com/Itseez/opencv.git
cd opencv/
mkdir build

Install required packages

dnf install tbb-devel eigen3-devel
# If you need video (for png, jpeg only this isn't required)
#dnf install ffmpeg-devel

Prepare `cmake`

One thing that I didn't realise before, is that cmake options are cumulative across commandline invocations :

cd ../opencv/build # ensure we're in the right place
cmake -D WITH_TBB=ON -D WITH_EIGEN=ON -D WITH_JAVA=OFF ..
cmake -D BUILD_DOCS=OFF -D BUILD_TESTS=OFF -D BUILD_PERF_TESTS=OFF -D BUILD_EXAMPLES=OFF ..
cmake -D WITH_OPENCL=OFF -D WITH_CUDA=OFF -D BUILD_opencv_gpu=OFF -D BUILD_opencv_gpuarithm=OFF -D BUILD_opencv_gpubgsegm=OFF -D BUILD_opencv_gpucodec=OFF -D BUILD_opencv_gpufeatures2d=OFF -D BUILD_opencv_gpufilters=OFF -D BUILD_opencv_gpuimgproc=OFF -D BUILD_opencv_gpulegacy=OFF -D BUILD_opencv_gpuoptflow=OFF -D BUILD_opencv_gpustereo=OFF -D BUILD_opencv_gpuwarping=OFF ..
cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr ..

Build

cd ../build  # ensure we're in the right place
make
sudo make install

Test that Python integration works

Documentation is available

python
Python 2.7.11 (default, Jun 21 2016, 09:15:12)
[GCC 6.1.1 20160510 (Red Hat 6.1.1-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.1.0-dev'