Papers › CrossFormer: A Versatile Vision Transformer Hinging on Cross-scale Attention

CrossFormer: A Versatile Vision Transformer Hinging on Cross-scale Attention

31 Jul 2021ICLR 2022 4arXiv:2108.00154archive 2025-07-28

Wenxiao Wang, Lu Yao, Long Chen, Binbin Lin, Deng Cai, Xiaofei He, Wei Liu

Transformers have made great progress in dealing with computer vision tasks. However, existing vision transformers do not yet possess the ability of building the interactions among features of different scales, which is perceptually important to visual inputs. The reasons are two-fold: (1) Input embeddings of each layer are equal-scale, so no cross-scale feature can be extracted; (2) to lower the computational cost, some vision transformers merge adjacent embeddings inside the self-attention module, thus sacrificing small-scale (fine-grained) features of the embeddings and also disabling the cross-scale interactions. To this end, we propose Cross-scale Embedding Layer (CEL) and Long Short Distance Attention (LSDA). On the one hand, CEL blends each embedding with multiple patches of different scales, providing the self-attention module itself with cross-scale features. On the other hand, LSDA splits the self-attention module into a short-distance one and a long-distance counterpart, which not only reduces the computational burden but also keeps both small-scale and large-scale features in the embeddings. Through the above two designs, we achieve cross-scale attention. Besides, we put forward a dynamic position bias for vision transformers to make the popular relative position bias apply to variable-sized images. Hinging on the cross-scale attention module, we construct a versatile vision architecture, dubbed CrossFormer, which accommodates variable-sized inputs. Extensive experiments show that CrossFormer outperforms the other vision transformers on image classification, object detection, instance segmentation, and semantic segmentation tasks. The code has been released: https://github.com/cheerss/CrossFormer.

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cheerss/CrossFormer officialmentioned in papermentioned on GitHubpytorchMIT report
conceptofmind/Crossformer-flax mentioned on GitHubjaxMIT report

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Tasks

Image ClassificationInstance SegmentationObject DetectionSemantic Segmentationimage-classificationobject-detection

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Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Semantic Segmentation ADE20K CrossFormer (ImageNet1k-pretrain, UPerNet, multi-scale test) Validation mIoU 51.4 #97 of 235 Archive leaderboard report
Semantic Segmentation ADE20K val CrossFormer (ImageNet1k-pretrain, UPerNet, multi-scale test) Pixel Accuracy 84.0% #46 of 95 Archive leaderboard report
Semantic Segmentation ADE20K val CrossFormer (ImageNet1k-pretrain, UPerNet, multi-scale test) mIoU 51.4% #46 of 95 Archive leaderboard report

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