h1. How to contribute

We suppose that you've seen the http://opencv.org/contribute.html page, and want to share some code. If so, good news for you, OpenCV project now has a mirror on the GitHub! And if you're familiar with that hosting, you can contribute in a familiar and friendly way. So, the preferred way to propose your code is to create a pull request on the GitHub. This way it will be automatically tested and reviewed: http://pullrequest.opencv.org. Here is the right project to fork: https://github.com/itseez/opencv.

h2. Overall process

# You fork OpenCV, code and work on all prerequisites from below.

# You make a pull request that is processed according to the process described below. Please provide timely response for reviewers, otherwise you submission could be postponed or even rejected.

# Repeat from the beginning =)

Here is how pull requests are processed:

!https://docs.google.com/drawings/pub?id=1_m7oVQ4CvoMxZn63N1_TyhhazmLLWY5uLEGUyPCERLo&w=960&h=720!

h2. Prerequisites

Below are some recommendations for contributors. They are raw, but can be used as a starting point for anybody who wants to see his code added to the library.

> We would gladly accept such a contribution, but because of little resources available on our side, I would ask you to do all the preparations. Here is the checklist, including both generic items and the specific things related to your code that I found after brief inspection:

# A prerequisite: is the algorithm patented? If yes, then we may not be that interested in putting it in.

# License - the current license is fine, it's compatible with OpenCV.

# Interface. Here some work is needed to make this code a seamless part of OpenCV.

** @M_PI -> CV_PI@

** You should remove all the static constants from the header. it's not portable and generally a bad practice. Use defines and enumerations.

** cv:: and std:: should not be used in the header, since all the stuff is already inside cv namespace and we already have "using std::vector", "using std::string" directives.

** "m_" in member names should be dropped, we do not this convention in OpenCV.

# Implementation.

** The code should be portable, it should compile fine on ARM too, for example. Therefore, you should not use SSE2 intrinsics outside of conditional compilation. Instead of "#ifdef USE_SSE" you should use "#if CV_SSE2".

** Avoiding duplication of existing OpenCV functionality. 

** Writing to cerr should be replaced with CV_Error() calls.

# Documentation.

** Documentation in RST format should be provided for the functionality. Check http://docs.opencv.org/modules/features2d/doc/feature_detection_and_description.html#orb as example.

# You should provide sample code.

** help() function should be added, check opencv/samples/cpp.

# Regression tests - the code should include some regression tests.

** Please, take a look at opencv/modules/features2d/test/test_features2d.cpp. You will need to add a similar test for your code.

# Integration

** Take the latest version of our repository or fork from our github mirror at https://github.com/Itseez/opencv/

** Add your code

** Insert documentation and add the test to the corresponding module

** Build OpenCV, run tests. If you have access to both Linux and Windows - great! Sometimes GCC-approved code does not built with MSVC and vice versa.

** Create pull request on github.com or create patch file or and submit it as patch at http://code.opencv.org/projects/opencv/issues/new.