Identification is a more complex task than verification. In this case, the Face Recognition is provided a probe image to attempt to match it with a biometric reference in the gallery (or not). This represents a one-to-many problem. In addition, we need to further differentiate between closed-set identification problems and open-set identification problems.
In a closed-set identification problem we want to identify a person that we know is in the reference database or gallery (in other words for any possible identification we want to make we know beforehand that the person to be identified is in the database).
Open-set identification is more complex in that we do not know in advance whether the person to be identified is or is not in the reference database.
Face Recognition app tries to solve closed-set identification problem, with the use of multiple techniques i.e. skin grabbing, Principal component analysis and feature based recognition.