用分布一致性损失提升逆问题重建质量,避免过拟合噪声。
Distributional Consistency Loss: Beyond Pointwise Data Terms in Inverse Problems
- 用统计分布校准替代逐点匹配,评估测量值与估计噪声分布的一致性。
- 在图像去噪中无需早停,PSNR提升;在医学成像中减少伪影,增强正则化效果。
- 适用于噪声分布已知的无监督逆问题,特别适合深度图像先验场景。
从含噪观测中恢复真实信号是医学影像、地球物理和信号处理等领域逆问题的核心挑战。现有方法在先验约束(正则化)与数据一致项之间权衡。传统数据保真损失如均方误差(MSE)或负对数似然追求与含噪测量的逐点匹配,常导致过拟合噪声。本文提出分布一致性(DC)损失,以整体统计一致性替代逐点匹配:检验观测值是否与当前估计所隐含的噪声分布一致。该损失可直接替换标准数据一致性项,兼容现代无监督正则化方法,无需成对数据;优化方式与传统损失相同;且无需早停或先验即可避免噪声过拟合。其适用范围涵盖测量噪声分布已知且数据由多个独立含噪值构成的实际逆问题。我们在两个典型场景验证:一是在基于深度图像先验的图像去噪中,用DC替代MSE后无需早停,峰值信噪比(PSNR)更高;二是在泊松噪声下的医学图像重建中,显著减少高迭代次数下的伪影,并提升手工设计正则化的有效性。结果表明,DC损失为一类噪声主导的无监督逆问题提供了统计基础扎实、性能更优的数据保真替代方案。
原文摘要 · Abstract (English)
Recovering true signals from noisy measurements is a central challenge in inverse problems spanning medical imaging, geophysics, and signal processing. Current methods balance prior signal priors (regularization) with agreement with noisy data (data-fidelity). Conventional data-fidelity loss functions, such as mean-squared error (MSE) or negative log-likelihood, seek pointwise agreement with noisy measurements, often leading to overfitting to noise. In this work, we instead evaluate data-fidelity collectively by testing whether the observed measurements are statistically consistent with the noise distributions implied by the current estimate. We introduce distributional consistency (DC) loss, a data-fidelity objective that replaces pointwise matching with distribution-level calibration. DC loss acts as a direct and practical plug-in replacement for standard data consistency terms: i) it is compatible with modern unsupervised regularizers that operate without paired measurement-ground-truth data, ii) it is optimized in the same way as traditional losses, and iii) it avoids overfitting to measurement noise without early stopping or priors. Its scope naturally fits many practical inverse problems where the measurement-noise distribution is known and where the measured dataset consists of many independent noisy values. We demonstrate efficacy in two key example application areas: i) in image denoising with deep image prior, using DC instead of MSE loss removes the need for early stopping and achieves higher PSNR; ii) in medical image reconstruction from Poisson-noisy data, DC loss reduces artifacts in highly-iterated reconstructions and enhances the efficacy of hand-crafted regularization. These results position DC loss as a statistically grounded, performance-enhancing alternative to conventional fidelity losses for an important class of unsupervised noise-dominated inverse problems.
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