This repo contains different implementations of Guided Filter.

Update: I reported this to opencv_contrib maintainer, see issues here opencv/opencv_contrib#760

Why would I set this repo?

Guided image filtering has been quite useful in computer vision since it was first introduced in 2010 by Kaiming He. And Guided Filter is now included in official OpenCV 3.0 as a new function.

I have been using guided image filtering for a while. At first I implemented it myself in C. After OpenCV 3.0 included Guided Filter, I tested it and compared the results with my own implementation and the MATLAB version offered at the author's website.

The OpenCV 3.0's official version of Guided Filter is quite fast. But I found that in some cases, e.g. some particular parameters, the OpenCV version might get wrong results. However, with the same parameters, the MATLAB version and my own implementation still get reasonable and correct results.

Here is one of the comparison below.

This is not the only instance that the OpenCV version gets wrong results.

FYI, the parameters:

• radius:3
• eps:1e-6
• using color image as the guidance

The code:

• My own implementation
• MATLAB codes by author
• OpenCV 3.0 source code