Selective-generative feature representations for generalized zero-shot open-set classification by learning a tightly clustered space

Abstract

Generating pseudo unseen samples is currently an effective approach for addressing the generalized zero-shot classification (GZSC) problem. However, in practical scenarios, the test set may contain open-set samples without semantic representations. Generalized zero-shot open-set classification (GZSOSC) extends GZSC tasks by simultaneously dealing with samples from seen, unseen, and open-set classes. In this paper, we propose a novel method to learn selective-generative feature representations (SGFR) to tackle the GZSOSC problem. Firstly, to handle the lack of unseen samples, we introduce a simple yet effective unseen feature generation method that leverages the seen–unseen relationships. Through an efficient alternating optimization strategy, we learn the seen–unseen relationships and the unseen visual centers. Secondly, to address the lack of open-set samples, we focus on learning a tightly clustered space for both seen and unseen classes. This enables effective open-set feature selection. We utilize the selected open-set samples to generate high-quality open-set features, thus enhancing the diversity of open-set samples. Extensive experiments are conducted to demonstrate the effectiveness of SGFR in handling the GZSOSC task.