  Semantic segmentation tasks naturally require high-resolution information for
pixel-wise segmentation and global context information for class prediction.
While existing vision transformers demonstrate promising performance, they
often utilize high resolution context modeling, resulting in a computational
bottleneck. In this work, we challenge conventional wisdom and introduce the
Low-Resolution Self-Attention (LRSA) mechanism to capture global context at a
significantly reduced computational cost. Our approach involves computing
self-attention in a fixed low-resolution space regardless of the input image's
resolution, with additional 3x3 depth-wise convolutions to capture fine details
in the high-resolution space. We demonstrate the effectiveness of our LRSA
approach by building the LRFormer, a vision transformer with an encoder-decoder
structure. Extensive experiments on the ADE20K, COCO-Stuff, and Cityscapes
datasets demonstrate that LRFormer outperforms state-of-the-art models. The
code will be made available at https://github.com/yuhuan-wu/LRFormer.
