EFFICIENT WATCHLIST SEARCHING WITH NORMALIZED SIMILARITY

Methods and systems for face recognition and response include extracting a face image from a video stream. A pre-processed index is searched for a watchlist image that matches the face image, based on a similarity distance that is computed from a normalized similarity score to satisfy metric properties. The index of the watchlist includes similarity distances between face images stored in the watchlist. An action is performed responsive to a determination that the extracted face image matches the watchlist image.