Robust Metric Boosts Transfer

Transfer metric learning (TML) aims to improve the metric learning in target domains by transferring knowledge from related tasks, where the distance metrics are strong and reliable. Existing TML approaches only focus on how to transfer the source metric knowledge, which is often prone to be over-fitting to the source domain. In this paper, we study how to train a source metric that is appropriate for transfer and then design a general deep TML method for effective metric transfer. In particular, we propose to learn the source metric parameterized by a deep neural network in an adversarial way and then transfer the metric to the target domain by embedding imitation, which allows the inputs of source and target domains to be heterogeneous. Besides, we restrict the size of the target metric network to be small so that the inference is efficient in the target domain. Results in the popular face verification application demonstrate the effectiveness of our method.