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arXiv 2209.12075eess.IVcs.CV

用于掩码感知高光谱图像重建的S^2-Transformer

S^2-Transformer for Mask-Aware Hyperspectral Image Reconstruction

School of Information, Rochester Institute of Technology(罗切斯特理工学院信息学院);Meta GenAI(元宇宙生成式人工智能部门);Shanghai Jiao Tong University(上海交通大学);Westlake University(西湖大学)

Jiamian Wang, Kunpeng Li, Yulun Zhang, Xin Yuan, Zhiqiang Tao

AI总结:

针对高光谱SCI重建中注意力设计局限、信息纠缠及掩码数据丢失问题,提出带并行注意力与掩码感知学习的S^2-Transformer,实验证明其性能优于现有最优方法。

摘要:

快照压缩成像(Snapshot compressive imaging, SCI)作为一种捕捉高光谱图像的新兴方式迅速兴起。它通过光学编码器将三维数据压缩为二维测量值,再采用软件解码器进行信号重建。近年来,编码孔径快照压缩成像仪(coded aperture snapshot compressive imager, CASSI)搭配Transformer重建后端的代表性SCI系统展现出高保真的传感性能。然而,主流的空间与光谱注意力设计在高光谱建模中存在局限性:空间注意力值描述像素间相关性,却忽略了每个像素内部的跨光谱变化;光谱注意力的规模无法随token空间尺寸扩展,进而成为信息分配的瓶颈。此外,CASSI将空间与光谱信息纠缠在二维测量值中,为信息解缠与建模设置了障碍。同时,CASSI使用物理二值掩码遮挡光线,导致被掩码区域的数据丢失。为解决上述挑战,我们提出了一种空间-光谱(S2-)Transformer,该模型采用并行注意力设计与掩码感知学习策略。首先,我们系统探究了不同空间(-光谱)注意力设计的优缺点,在此基础上发现并行执行两种注意力能很好地解缠并建模混合信息。其次,被掩码像素的预测难度更高,应与未掩码像素区别对待。我们通过将掩码编码的预测结果作为不确定性估计器,根据掩码结构自适应地调整损失惩罚的优先级。我们从理论上探讨了所提学习策略下掩码区域与未掩码区域不同的收敛趋势。大量实验表明,所提方法的结果平均优于当前最优方法。

英文摘要:

Snapshot compressive imaging (SCI) surges as a novel way of capturing hyperspectral images. It operates an optical encoder to compress the 3D data into a 2D measurement and adopts a software decoder for the signal reconstruction. Recently, a representative SCI set-up of coded aperture snapshot compressive imager (CASSI) with Transformer reconstruction backend remarks high-fidelity sensing performance. However, dominant spatial and spectral attention designs show limitations in hyperspectral modeling. The spatial attention values describe the inter-pixel correlation but overlook the across-spectra variation within each pixel. The spectral attention size is unscalable to the token spatial size and thus bottlenecks information allocation. Besides, CASSI entangles the spatial and spectral information into a 2D measurement, placing a barrier for information disentanglement and modeling. In addition, CASSI blocks the light with a physical binary mask, yielding the masked data loss. To tackle above challenges, we propose a spatial-spectral (S2-) Transformer implemented by a paralleled attention design and a mask-aware learning strategy. Firstly, we systematically explore pros and cons of different spatial (-spectral) attention designs, based on which we find performing both attentions in parallel well disentangles and models the blended information. Secondly, the masked pixels induce higher prediction difficulty and should be treated differently from unmasked ones. We adaptively prioritize the loss penalty attributing to the mask structure by referring to the mask-encoded prediction as an uncertainty estimator. We theoretically discuss the distinct convergence tendencies between masked/unmasked regions of the proposed learning strategy. Extensive experiments demonstrate that on average, the results of the proposed method are superior over the state-of-the-art method.

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