  Cross-spectral image guided denoising has shown its great potential in
recovering clean images with rich details, such as using the near-infrared
image to guide the denoising process of the visible one. To obtain such image
pairs, a feasible and economical way is to employ a stereo system, which is
widely used on mobile devices. Current works attempt to generate an aligned
guidance image to handle the disparity between two images. However, due to
occlusion, spectral differences and noise degradation, the aligned guidance
image generally exists ghosting and artifacts, leading to an unsatisfactory
denoised result. To address this issue, we propose a one-stage
transformer-based architecture, named SGDFormer, for cross-spectral Stereo
image Guided Denoising. The architecture integrates the correspondence modeling
and feature fusion of stereo images into a unified network. Our transformer
block contains a noise-robust cross-attention (NRCA) module and a spatially
variant feature fusion (SVFF) module. The NRCA module captures the long-range
correspondence of two images in a coarse-to-fine manner to alleviate the
interference of noise. The SVFF module further enhances salient structures and
suppresses harmful artifacts through dynamically selecting useful information.
Thanks to the above design, our SGDFormer can restore artifact-free images with
fine structures, and achieves state-of-the-art performance on various datasets.
Additionally, our SGDFormer can be extended to handle other unaligned
cross-model guided restoration tasks such as guided depth super-resolution.
