Face selection heuristic

[ledermauss]

Hi! Awesome project! I have been using it for the past days and I wonder something: what do you thing is the best heuristic to select a face, when multiple are detected but only one is in the picture?

Basically, when running through a video, sometimes FER detects "blobs" as faces, which in reality are not. I was wondering if you have any criteria to pick the right one. I saw that in the method top_emotion you just take the first one, is that always the case?

[JustinShenk]

Good question on how to eliminate false positives. It could be interesting to add a single face mode that only keeps the largest face, since false positives are usually smaller.