Before revision:  As a core of deep metric learning, a novel quadruplet data pair design considering imbalance class is proposed with reference to traditional deep metric learning . Based on such data pair, this paper proposes a quadruplet loss function which takes into account the inter-class distance and the intra-class data distribution , and pays special attention to imbalanced sample pairs .
After revision:  As a core of deep metric learning, a novel quadruplet data pair design manner are considered . Based on such data pair, this paper proposes a quadruplet loss function which takes into account the inter-class distance and the intra-class data distribution , and pays special attention to imbalanced sample pairs .