Counterfactual learning and saliency augmentation for weakly supervised semantic segmentation

The weakly supervised semantic segmentation based on image-level annotation has garnered widespread attention due to its excellent annotation efficiency and remarkable scalability. Numerous studies have utilized class activation maps generated by classification networks to produce pseudo-labels and train segmentation models accordingly. However, these methods exhibit certain limitations: biased localization activations, co-occurrence from the background, and semantic absence of target objects. We re-examine the aforementioned issues from a causal perspective and propose a framework for CounterFactual Learning and Saliency Augmentation (CFLSA) based on causal inference. CFLSA consists of a debiased causal chain and a positional causal chain. The debiased causal chain, through counterfactual decoupling generation module, compels the model to focus on constant target features while disregarding background features. It effectively eliminates spurious correlations between foreground objects and the background. Additionally, issues of biased activation and co-occurring pixel are alleviated. Secondly, in order to enable the model to recognize more comprehensive semantic information, we introduce a saliency augmentation mechanism in the positional causal chain to dynamically perceive foreground objects and background information. It can facilitate pixel-level feedback, leading to improved segmentation performance. With the collaboration of both chains, CFLSA achieves advanced results on the PASCAL VOC 2012 and MS COCO 2014 datasets.