DINO is Also a Semantic Guider: Exploiting Class-aware Affinity for Weakly Supervised Semantic Segmentation

Weakly supervised semantic segmentation (WSSS) using image-level labels is a challenging task, with relying on Class Activation Map (CAM) to derive segmentation supervision. Although many efficient single-stage solutions have been proposed, their performance is hindered by the inherent ambiguity of CAM. This paper introduces a new approach, dubbed ECA, to Exploit the self-supervised Vision Transformer, DINO, inducing the Class-aware semantic Affinity to overcome this limitation. Specifically, we introduce a Semantic Affinity Exploitation module (SAE). It establishes the class-agnostic affinity graph through the self-attention of DINO. Using the highly activated patches on CAMs as 'seeds', we propagate them across the affinity graph and yield the Class-aware Affinity Region Map (CARM) as supplementary semantic guidance. Moreover, the selection of reliable 'seeds' is crucial to the CARM generation. Inspired by the observed CAM inconsistency between the global and local views, we develop a CAM Correspondence Enhancement module (CCE) to encourage dense local-to-global CAM correspondences, advancing high-fidelity CAM for seed selection in SAE. Our experimental results demonstrate that ECA effectively improves the model's object pattern understanding. Remarkably, it outperforms state-of-the-art alternatives on the PASCAL VOC 2012 and MS COCO 2014 datasets, achieving 90.1% upper bound performance compared to its fully supervised counterpart. Code is available at https://github.com/Wu0409/ECA.