Abstract
Terahertz (THz) tomographic imaging has recently attracted significant attention thanks to its non-invasive, non-destructive, non-ionizing, material-classification, and ultra-fast nature for object exploration and inspection. However, its strong water absorption nature and low noise tolerance lead to undesired blurs and distortions of reconstructed THz images. The diffraction-limited THz signals highly constrain the performances of existing restoration methods. To address the problem, we propose a novel multi-view Subspace-Attention-guided Restoration Network (SARNet) that fuses multi-view and multi-spectral features of THz images for effective image restoration and 3D tomographic reconstruction. To this end, SARNet uses multi-scale branches to extract intra-view spatio-spectral amplitude and phase features and fuse them via shared subspace projection and self-attention guidance. We then perform inter-view fusion to further improve the restoration of individual views by leveraging the redundancies between neighboring views. Here, we experimentally construct a THz time-domain spectroscopy (THz-TDS) system covering a broad frequency range from 0.1 to 4 THz for building up a temporal/spectral/spatial/material THz database of hidden 3D objects. Complementary to a quantitative evaluation, we demonstrate the effectiveness of our SARNet model on 3D THz tomographic reconstruction applications.
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Notes
Project site: https://github.com/wtnthu/THz_Tomography.
Dataset site: https://github.com/wtnthu/THz_Data.
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Acknowledgements
This work was financially supported in part by the National Science and Technology Council (NSTC), Taiwan, under Grants 111-2221-E-007-046-MY3, 111-2634-F-002-023, and 110-2636-E-007-017.
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Su, WT., Hung, YC., Yu, PJ. et al. Making the Invisible Visible: Toward High-Quality Terahertz Tomographic Imaging via Physics-Guided Restoration. Int J Comput Vis 131, 2388–2407 (2023). https://doi.org/10.1007/s11263-023-01812-y
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DOI: https://doi.org/10.1007/s11263-023-01812-y