SGDE: Self-supervised Geometry Degradation Estimation Framework for Coded Aperture Compressive Spectral Imaging

Coded Aperture Snapshot Spectral Imaging (CASSI) has emerged as a prominent technique for efficient hyperspectral imaging. However, the tight coupling between physical encoding and computational decoding makes CASSI highly sensitive to slight hardware misalignments, which can significantly degrade reconstruction quality. Existing methods either assume ideal imaging conditions or rely on offline calibration, making them vulnerable to dynamic perturbations, such as thermal expansion and mechanical vibrations, which cause mask shifts. To address these limitations, we propose a Self-supervised Geometry Degradation Estimation (SGDE) framework that explicitly models mask misalignments as an affine transformation and embeds it into the imaging model. SGDE jointly estimates affine parameters and reconstructs the hyperspectral image in a self-supervised manner, eliminating the need for reference targets or device-specific training data. Furthermore, we introduce a multi-kernel estimation strategy to enhance the robustness of degradation estimation under large perturbations. Extensive experiments on both simulated and real-world datasets demonstrate that SGDE achieves superior robustness against mask misalignments. Moreover, the estimated affine parameters can be directly integrated into existing reconstruction algorithms, enabling plug-and-play degradation estimation for practical CASSI systems. The code is available at https://github.com/heyuqiao/SGDE.