Install Latest Version of OpenCV on Debian from Sources

Here is how to install the latest OpenCV version on Debian from sources. If you are looking for tutorials on Mac OS X, you may want to check out this post.

Before doing anything, make sure to install necessary packages:
$ sudo apt-get install -y build-essential cmake git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev

By the way, if you are not sure how to setup sudo in Debian, please take a look here.

Now, download the latest sources from its official Github repository. This will take some time.
$ git clone https://github.com/opencv/opencv.git

Else, you may want to just check out Linux component from here.

Create release folder and run cmake:
$ mkdir opencv/release && cd opencv/release
$ cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_EXAMPLES=YES ..

For more OpenCV cmake options, take a look here starting at line 171. If you would like to be able to debug the OpenCV library, you will need to compile with debug symbols. This post explains how to do so.

Now, we are ready to compile and install:
$ make -j $(nproc)
$ sudo make install

Let's test and see if you can link the library. Create test.cpp file with the following:
#include <opencv2/core.hpp>
#include <iostream>
using namespace cv;
int main() {
Mat test(3,2,CV_8UC1); 
std::cout << test << std::endl;

return 0;
}

Compile and run:
$ g++ test.cpp $(pkg-config --libs opencv)
$ ./a.out
./a.out: error while loading shared libraries: libopencv_shape.so.3.1: cannot open shared object file: No such file or directory

OK. This is because ldconfig hasn't been updated.
$ sudo ldconfig
$ ./a.out
[ 10,  60;
  71,   0;
   0,   0]

Enjoy!