用神经网络自动学习反问题的正则化参数,实现快速高质成像。
Deep regularization networks for inverse problems with noisy operators
- 通过神经算子直接映射输入到正则化参数,跳过传统迭代优化。
- 在弹性板损伤演化成像中,图像对比度提升且处理速度显著加快。
- 基于偏差原理训练,无需先验知识,适合复杂环境实时成像。
针对由噪声数据构建主算子的大规模反问题,提出一种监督学习方法以加速时空正则化过程,实现实时成像。该方法利用神经算子将散射方程右侧的每种模式映射到其对应的正则化参数。训练分两步:首先基于莫罗佐夫偏差原理生成的低分辨率正则化图进行训练,使用非最优阈值;其次通过最小化Tikhonov损失并受验证损失调控来优化网络预测。第二步使初步近似图向高质量图像逼近。该方法可直接从测试数据学习,无需先验最优正则化图知识。网络在低分辨率数据上训练后,能快速生成高分辨率成像所需的密集正则化图。强调训练损失函数对泛化能力的影响,表明基于偏差原理逻辑训练的网络能生成更高对比度图像。此时训练涉及多目标优化,本文提出一种自适应选择损失权重的方法,无需额外优化过程。在弹性板损伤演化成像任务中进行了合成实验,结果表明,偏差信息引导的正则化网络不仅加速成像,还在复杂环境中显著提升图像质量。
原文摘要 · Abstract (English)
A supervised learning approach is proposed for regularization of large inverse problems where the main operator is built from noisy data. This is germane to superresolution imaging via the sampling indicators of the inverse scattering theory. We aim to accelerate the spatiotemporal regularization process for this class of inverse problems to enable real-time imaging. In this approach, a neural operator maps each pattern on the right-hand side of the scattering equation to its affiliated regularization parameter. The network is trained in two steps which entails: (1) training on low-resolution regularization maps furnished by the Morozov discrepancy principle with nonoptimal thresholds, and (2) optimizing network predictions through minimization of the Tikhonov loss function regulated by the validation loss. Step 2 allows for tailoring of the approximate maps of Step 1 toward construction of higher quality images. This approach enables direct learning from test data and dispenses with the need for a-priori knowledge of the optimal regularization maps. The network, trained on low-resolution data, quickly generates dense regularization maps for high-resolution imaging. We highlight the importance of the training loss function on the network's generalizability. In particular, we demonstrate that networks informed by the logic of discrepancy principle lead to images of higher contrast. In this case, the training process involves many-objective optimization. We propose a new method to adaptively select the appropriate loss weights during training without requiring an additional optimization process. The proposed approach is synthetically examined for imaging damage evolution in an elastic plate. The results indicate that the discrepancy-informed regularization networks not only accelerate the imaging process, but also remarkably enhance the image quality in complex environments.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。