Pansharpening via predictive filtering with element-wise feature mixing

Pansharpening is a crucial technique in remote sensing for enhancing spatial resolution by fusing low spatial resolution multispectral (LRMS) images with high spatial panchromatic (PAN) images. Existing deep convolutional networks often face challenges in capturing fine details due to the homogeneous operation of convolutional kernels. In this paper, we propose a novel predictive filtering approach for pansharpening to mitigate spectral distortions and spatial degradations. By obtaining predictive filters through the fusion of LRMS and PAN and conducting filtering operations using unique kernels assigned to each pixel, our method reduces information loss significantly. To learn more effective kernels, we propose an effective fine-grained fusion method for LRMS and PAN features, namely element-wise feature mixing. Specifically, features of LRMS and PAN will be exchanged under the guidance of a learned mask. The value of the mask signifies the extent to which the element will be mixed. Extensive experimental results demonstrate that the proposed method achieves better performances than the state-of-the-art models with fewer parameters and lower computations. Visual comparisons indicate that our model pays more attention to details, which further confirms the effectiveness of the proposed fine-grained fusion method. Codes are available at https://github.com/yc-cui/PreMix.