Enhanced Window-Based Self-Attention with Global and Multi-Scale Representations for Remote Sensing Image Super-Resolution

Transformers have recently gained significant attention in low-level vision tasks, particularly for remote sensing image super-resolution (RSISR). The vanilla vision transformer aims to establish long-range dependencies between image patches. However, its global receptive field leads to a quadratic increase in computational complexity with respect to spatial size, rendering it inefficient for addressing RSISR tasks that involve processing large-sized images. In an effort to mitigate computational costs, recent studies have explored the utilization of local attention mechanisms, inspired by convolutional neural networks (CNNs), focusing on interactions between patches within small windows. Nevertheless, these approaches are naturally influenced by smaller participating receptive fields, and the utilization of fixed window sizes hinders their ability to perceive multi-scale information, consequently limiting model performance. To address these challenges, we propose a hierarchical transformer model named the Multi-Scale and Global Representation Enhancement-based Transformer (MSGFormer). We propose an efficient attention mechanism, Dual Window-based Self-Attention (DWSA), combining distributed and concentrated attention to balance computational complexity and the receptive field range. Additionally, we incorporated the Multi-scale Depth-wise Convolution Attention (MDCA) module, which is effective in capturing multi-scale features through multi-branch convolution. Furthermore, we developed a new Tracing-Back Structure (TBS), offering tracing-back mechanisms for both proposed attention modules to enhance their feature representation capability. Extensive experiments demonstrate that MSGFormer outperforms state-of-the-art methods on multiple public RSISR datasets by up to 0.11–0.55 dB.