BTG-Net++: Enhanced Bi-directional Task-Guided Network for Few-Shot Fine-Grained Image Classification

In recent years, a number of effective Few-Shot Fine-Grained Image Classification (FS-FGIC) methods have been proposed, which mainly focus on extracting discriminative information within high-level features in a single episode/task. However, this is insufficient for addressing the cross-task challenges of FS-FGIC, which is represented in two aspects. On the one hand, from the perspective of the Fine-Grained Image Classification (FGIC) task, there is a need to supplement the model with mid-level features containing rich fine-grained information. On the other hand, from the perspective of the Few-Shot Learning (FSL) task, explicit modeling of cross-task general knowledge is required. In this paper, we propose a novel Enhanced Bi-directional Task-Guided Network (BTG-Net++) to tackle these issues. Specifically, from the FGIC task perspective, we design the Semantic-Guided Noise Filtering (SGNF) module to filter noise on mid-level features rich in detailed information with the assistance of high-level features. Further, from the FSL task perspective, the General Knowledge Prompt Modeling (GKPM) module is proposed to retain the cross-task general knowledge by utilizing the prompting mechanism, thereby enhancing the model’s generalization performance on unseen novel classes. We have conducted extensive experiments on five fine-grained benchmark datasets, and the results demonstrate that BTG-Net++ shows considerable improvements compared with state-of-the-art methods.