CAA: Class-Aware Affinity calculation add-on for semantic segmentation

Abstract

Leveraging contextual dependencies is a commonly used technique to enhance the performance of image segmentation. However, existing solutions do not effectively catch the class-level association between the pixels along the boundary across the objects of the different classes but focus more on the local pixel-to-pixel relation. This work proposes a Class-Aware Affinity module (CAA) that considers both pixel-to-pixel relation and pixel-to-class association. We try to argue that the pixel-to-pixel relations still catch the relation (e.g. similarity, attention, or affiliation) on the local texture level. At the same time, it should also consider the association between the pixel and the class context produced by the given image. Pixel-to-class association can best reveal the co-occurrent dependency on the semantic level between the given pixels and their nearby context. Such pixel-to-class association combined with the pixel-to-pixel relations aggregating the local texture information will best mitigate the confusion caused in the boundary regions across the objects of the different classes. Moreover, the proposed framework can serve as a generic add-on to be integrated with the existing image segmentation solution to boost the current performance. Equipped with CAA, we achieve promising performance against the existing work with 54.59% mIoU on ADE20K, 49.96% mIoU on COCO-Stuff10k, and 64.38% mIoU on Pascal-Context.