Hello Krzysztof!
I have Matlab R2015a and I have succesfully installed OpenCV in my computer following the documentation from the MathWorks Team.
The process is well documented in the following video (It lasts for ~10.5 minutes). I assure you that by following these instructions in the end you'll only need to:
- Download the 'Computer Vision System Toolbox OpenCV Interface' package.
- and download/install 'Microsoft Visual C++ 2012 (C)' compiler (Do not go for newer versions of this compiler, OpenCV will only work with version 2012. Search for this version. It's a must!)
(Put extra attention to the video!)
Let me know how it goes.