Meta Parsing Networks: Towards Generalized Few-shot Scene Parsing with Adaptive Metric Learning

Recent progress in few-shot segmentation usually aims at performing novel object segmentation using a few annotated examples as guidance. In this work, we advance this few-shot segmentation paradigm towards a more challenging yet general scenario, i.e., Generalized Few-shot Scene Parsing (GFSP). In this task, we take a fully annotated image as guidance to segment all pixels in a query image. Our mission is to study a generalizable and robust segmentation network from the meta-learning perspective so that both seen and unseen categories can be correctly recognized. Different from previous practices, this task performs segmentation on a joint label space consisting of both previously seen and novel categories. Moreover, pixels from these multiple categories need to be simultaneously taken into account, which is actually not well explored before. Accordingly, we present Meta Parsing Networks (MPNet) to better exploit the guidance information in the support set. Our MPNet contains two basic modules, i.e., the Adaptive Deep Metric Learning (ADML) module and the Contrastive Inter-class Distraction (CID) module. Specially, the ADML takes the annotated pixels from the support image as the guidance and adaptively produces high-quality prototypes for learning a deep comparison metric. In addition, MPNet further introduces the CID module learning to enlarge the feature discrepancy of different categories in the embedding space, leading the MPNet to generate more discriminative feature embeddings. We conduct experiments on two newly constructed benchmarks, i.e., GFSP-Cityscapes and GFSP-Pascal-Context. Extensive ablation studies well demonstrate the effectiveness and generalization ability of our MPNet.