Alleviating Domain Shift via Discriminative Learning for Generalized Zero-Shot Learning

In zero-shot learning (ZSL) tasks, especially in generalized zero-shot learning (GZSL), the model tends to classify unseen test samples into seen categories, which is well known as the domain shift problem, because the model is trained from seen samples without unseen samples. Recently, generative adversarial network (GAN) based methods have achieved good performance in GZSL, which replace real unseen features by synthesizing fake ones to mitigate the domain shift. However, the domain shift problem is still not well solved, due to the lacking of unseen samples in the training progress of the GAN generator. In this paper, we propose a generative model named discriminative learning GAN (DL-GAN) to alleviate the domain shift in GZSL. Specifically, the DL-GAN is designed with three novel components: a dual-stream embedding model that aligns features to the ground-truth attributes to extract discriminative latent attributes from features, an attribute-based generative model that generates high-quality unseen features from semantic attributes to guarantee inter-class discriminability and semantic consistency, and a seen/unseen classifier that leverages validation samples to distinguish seen samples from unseen ones. Experimental results on four widely used datasets verify that our proposed approach significantly outperforms the state-of-the-art methods under the GZSL protocol.