How to remove false matches from FLANNBASED Matcher in OPENCV?

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I am trying to compare one image with multiple images and get a list of ALL matching images. I do NOT want to draw keypoints between images.

My solution is based on the following source code:

https://github.com/Itseez/opencv/blob/master/samples/cpp/matching_to_many_images.cpp

The above source code matches one image with multiple images and get best matching image.

I have modified the above sample and generated:

vector<vector<dmatch>> matches; vector<vector<dmatch>> good_matches; Now my question is how do I apply nearest neighbor search ratio to get good matches for multiple images?