Hyperspectral and multispectral remote sensing image fusion using SwinGAN with joint adaptive spatial-spectral gradient loss function

Hyperspectral remote sensing image (HSI) fusion with multispectral remote sensing images (MSI) improves data resolution. However, current fusion algorithms focus on local information and overlook long-range dependencies. The parameter of network tuning prioritizes global optimization, neglecting spatial and spectral constraints, and limiting spatial and spectral reconstruction capabilities. This study introduces SwinGAN, a fusion network combining Swin Transformer, CNN, and GAN architectures. SwinGAN's generator employs a detail injection framework to separately extract HSI and MSI features, fusing them to generate spatial residuals. These residuals are injected into the supersampled HSI to produce the final image, while a pure CNN architecture acts as the discriminator, enhancing the fusion quality. Additionally, we introduce a new adaptive loss function that improves image fusion accuracy. The loss function uses L1 loss as the content loss, and spatial and spectral gradient loss functions are introduced to improve the spatial representation and spectral fidelity of the fused images. Our experimental results on several datasets demonstrate that SwinGAN outperforms current popular algorithms in both spatial and spectral reconstruction capabilities. The ablation experiments also demonstrate the rationality of the various components of the proposed loss function.