Active Token Mixer
This addresses the core challenge in backbone architecture development for vision tasks, offering a novel operator that improves performance broadly, though it appears incremental in advancing token-mixing methods.
The paper tackles the problem of designing effective token-mixing mechanisms in vision backbones by proposing the Active Token Mixer (ATM), which actively incorporates contextual information across channels and tokens, resulting in ATMNet surpassing state-of-the-art models across various vision tasks.
The three existing dominant network families, i.e., CNNs, Transformers, and MLPs, differ from each other mainly in the ways of fusing spatial contextual information, leaving designing more effective token-mixing mechanisms at the core of backbone architecture development. In this work, we propose an innovative token-mixer, dubbed Active Token Mixer (ATM), to actively incorporate flexible contextual information distributed across different channels from other tokens into the given query token. This fundamental operator actively predicts where to capture useful contexts and learns how to fuse the captured contexts with the query token at channel level. In this way, the spatial range of token-mixing can be expanded to a global scope with limited computational complexity, where the way of token-mixing is reformed. We take ATM as the primary operator and assemble ATMs into a cascade architecture, dubbed ATMNet. Extensive experiments demonstrate that ATMNet is generally applicable and comprehensively surpasses different families of SOTA vision backbones by a clear margin on a broad range of vision tasks, including visual recognition and dense prediction tasks. Code is available at https://github.com/microsoft/ActiveMLP.