Face recognition

Learning a Similarity Metric Discriminatively, with Application to Face Verification (Siamese network)

http://yann.lecun.com/exdb/publis/pdf/chopra-05.pdf

Training a similarity metric from data

DeepFace: Closing the Gap to Human-Level Performance in Face Verification

https://research.fb.com/wp-content/uploads/2016/11/deepface-closing-the-gap-to-human-level-performance-in-face-verification.pdf

FaceNet: A Unified Embedding for Face Recognition and Clustering

https://arxiv.org/abs/1503.03832

$$||f(A^{(i)})-f(P^{(i)})||_2^2 + \alpha \lt ||f(A^{(i)})-f(N^{(i)})||_2^2$$

$$\text{Triplet loss}= \Big[||f(A^{(i)})-f(P^{(i)})||_2^2 - ||f(A^{(i)})-f(N^{(i)})||_2^2 + \alpha \Big]_+$$

$A^{(i)}$ : anchor of i-th triplet, $P^{(i)}$: positive example of i-th triplet, $N^{(i)}$: negative example of i-th triplet, $\alpha$: margin