What is the meaning of the confidence value from face recognition in openbr ?

[Kanishk Sharma]

Hi I have succesfully run the openbr library but when i use the face reognition using the following command : br -algorithm FaceRecognition -compare me.jpg you.jpg

using my own images it gives random values - it can be 2 sometimes and can be 20 sometimes. Kindly explain me the meaning of this value , is it some kind of confidence value - if yes then what is the threshold of the match.