利用雷达方位向子孔径分解,实现无需真实标签的卫星遥感图像增强。
A Deep Learning Iterative Framework for Sentinel-1 Stripmap Enhancement Based on Azimuth Doppler Decomposition

- 通过方位向子孔径重构生成自监督训练对,避免依赖外部数据。
- 在真实哨兵-1数据上,提升结构保真度(PSNR/SSIM)优于现有基线方法。
- 适用于多种雷达平台与成像模式,适合遥感图像处理研究者使用。
合成孔径雷达(SAR)影像可在全天候、全天时条件下进行地球观测,但因斑点噪声及其他成像伪影难以解读。哨兵-1(Sentinel-1, S1)是应用最广泛的星载SAR任务之一,提供系统性全球覆盖、高时间分辨率、双极化成像及免费数据。其中,条带模式(Stripmap, SM)分辨率最高,但斑点噪声与空间限制常阻碍对精细空间细节的需求。为此,本文提出一种基于方位向子孔径分解的自监督图像增强框架。该方法利用子孔径重建与全孔径图像间的物理一致性,无需外部传感器、仿真真值或多时相数据即可生成配对训练样本。框架融合单帧与多帧学习,并引入迭代推理机制,逐步优化图像质量。在真实S1 SM数据上的实验表明,所提方法在PSNR和SSIM指标上持续优于广泛应用的自监督深度学习基线MERLIN,而MERLIN在均方根等效噪声(ENL)上表现更优,揭示了结构保真与斑点平滑之间的权衡。总体结果表明,基于子孔径的监督是一种物理可解释、可复现且具备实用价值的S1图像增强方法,且可推广至其他SAR平台、极化方式与成像模式。
原文摘要 · Abstract (English)
Synthetic Aperture Radar (SAR) imagery enables all-weather, day-and-night Earth observation; however, it remains difficult to interpret due to speckle noise and other intrinsic imaging artifacts. Sentinel-1 (S1) constitutes one of the most widely used spaceborne SAR missions, offering systematic global coverage, high temporal resolution, dual-polarization imaging, and free data availability. Among S1 modes, Stripmap (SM) provides the highest resolution, yet speckle noise and spatial constraints often hinder applications requiring finer spatial detail. This motivates the need for effective image enhancement strategies. In this work, we propose a self-supervised enhancement framework for S1 SM imagery based on azimuth subaperture decomposition. The method exploits the physical consistency between subaperture reconstructions and the corresponding full-aperture image to generate paired training data without external sensors, simulated ground truth, or multi-temporal stacks. The proposed framework integrates single- and multi-frame learning and incorporates an iterative inference scheme that progressively refines image quality. Experiments on real S1 SM data show that the proposed approach consistently outperforms the widely adopted self-supervised deep learning baseline MERLIN, in terms of PSNR and SSIM, while MERLIN attains higher ENL, highlighting a trade-off between structural fidelity and speckle smoothing. Overall, the results demonstrate that subaperture-based supervision provides a physically grounded, reproducible, and operationally viable approach for SAR image enhancement using S1 data. It is worth noting that the proposed approach can be extended to other SAR platforms, polarizations, and acquisition modes.
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