用深度先验实现卫星图像修复并准确估计不确定性。
Deep priors for satellite image restoration with accurate uncertainties
- 在变分压缩自编码器的隐空间求解逆问题,提升修复效果。
- 无需训练即可调节正则强度,支持多传感器图像修复。
- 快速采样后验分布,适合需不确定性评估的应用场景。
卫星光学图像在地面接收时往往存在失真,需经过去噪、去模糊甚至超分辨率修复后才能使用。量化修复过程中的不确定性有助于降低误判风险。当前主流方法为深度学习,直接反演方法针对每种传感器训练专用网络,仅输出点估计且无不确定性。而深度正则化(DR)方法先学习目标图像的深度先验,再作为模型优化中的正则项,可适配多种传感器,并支持不确定性估计。本文提出VBLE-xz,一种在变分压缩自编码器(CAE)隐空间中求解逆问题的DR方法。通过训练无关的方法调节已训练CAE的比特率,动态调整正则强度;同时利用变分推断显式估计后验分布,在隐空间和图像空间联合估计相关不确定性。该方法实现快速后验采样,优于依赖马尔可夫链或扩散过程的现有方法。我们在超高分辨率模拟与真实普莱亚德斯(Pléiades)图像上进行综合实验,验证了VBLE-xz在性能、鲁棒性和可扩展性上的优势。结果表明,当需要不确定性量化时,VBLE-xz是直接反演方法的有力替代方案。代码见:https://github.com/MaudBqrd/VBLExz。
原文摘要 · Abstract (English)
Satellite optical images, upon their on-ground receipt, offer a distorted view of the observed scene. Their restoration, including denoising, deblurring, and sometimes super-resolution, is required before their exploitation. Moreover, quantifying the uncertainties related to this restoration helps to reduce the risks of misinterpreting the image content. Deep learning methods are now state-of-the-art for satellite image restoration. Among them, direct inversion methods train a specific network for each sensor, and generally provide a point estimation of the restored image without the associated uncertainties. Alternatively, deep regularization (DR) methods learn a deep prior on target images before plugging it, as the regularization term, into a model-based optimization scheme. This allows for restoring images from several sensors with a single network and possibly for estimating associated uncertainties. In this paper, we introduce VBLE-xz, a DR method that solves the inverse problem in the latent space of a variational compressive autoencoder (CAE). We adapt the regularization strength by modulating the bitrate of the trained CAE with a training-free approach. Then, VBLE-xz estimates relevant uncertainties jointly in the latent and in the image spaces by sampling an explicit posterior estimated within variational inference. This enables fast posterior sampling, unlike state-of-the-art DR methods that use Markov chains or diffusion-based approaches. We conduct a comprehensive set of experiments on very high-resolution simulated and real Pléiades images, asserting the performance, robustness and scalability of the proposed method. They demonstrate that VBLE-xz represents a compelling alternative to direct inversion methods when uncertainty quantification is required. The code associated to this paper is available in https://github.com/MaudBqrd/VBLExz.
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