Bug 416630

Currently recognition match is done using an average of all matches to a given person. This approach does not work well for people with high number of examples done at different age / hair color / angle. What makes things worse adding more examples usually makes matching worse as it means there are always distant examples outnumbering near ones. 

I tried nearest neighbor and it's pretty noise. What works best for me is to take average of N nearest examples (I tried 5 and 10). It eliminates noise yet finding great matches.

Another change that gave me good results is using adjusted cosine distance instead of regular one: each feature is normalized by it's mean across whole example database. E.g. if feature mean is high (e.g. 0.6), it does not have much effect on cosine as almost all vectors would be pointing into "positive" direction, while adjusted (n-0.6) will have vectors pointing into different sides providing meaningful input. It reduces overall similarly (I have to use 0.7 instead of 0.8-0.9 to find examples), but general quality seems better.

Note that I did not do a formal accuracy check for both changes yet. Tried to do it fast, but libraries produce "accuracy" that is low and rarely applicable as it does not take into account accuracy threshold (drop everything with match less than T)