论文标题

神经增强的Alista

Neurally Augmented ALISTA

论文作者

Behrens, Freya, Sauder, Jonathan, Jung, Peter

论文摘要

众所周知的是,许多迭代稀疏重建算法都可以展开,以产生可学习的神经网络,以改善经验性能。学会了一个主要的示例ISTA(LISTA),其中的权重,台阶大小和阈值是从训练数据中学到的。最近,已经引入了分析列表(ALISTA),结合了Lista等全面学习方法的强烈经验性能,同时保留了经典压缩感应算法的理论保证,并显着减少了学习的参数数量。但是,这些参数经过培训以实现预期,通常会导致单个目标的次优重建。因此,在这项工作中,我们引入了神经增强的ALISTA,其中使用LSTM网络用于重建过程中每个目标向量的每个目标向量分别计算步进大小和阈值。从理论上讲,这种适应性方法是通过重新审视Alista的恢复保证而动机的。我们表明,我们的方法进一步提高了稀疏重建中的经验性能,特别是随着压缩比变得更具挑战性,通过增加的余量优于现有算法。

It is well-established that many iterative sparse reconstruction algorithms can be unrolled to yield a learnable neural network for improved empirical performance. A prime example is learned ISTA (LISTA) where weights, step sizes and thresholds are learned from training data. Recently, Analytic LISTA (ALISTA) has been introduced, combining the strong empirical performance of a fully learned approach like LISTA, while retaining theoretical guarantees of classical compressed sensing algorithms and significantly reducing the number of parameters to learn. However, these parameters are trained to work in expectation, often leading to suboptimal reconstruction of individual targets. In this work we therefore introduce Neurally Augmented ALISTA, in which an LSTM network is used to compute step sizes and thresholds individually for each target vector during reconstruction. This adaptive approach is theoretically motivated by revisiting the recovery guarantees of ALISTA. We show that our approach further improves empirical performance in sparse reconstruction, in particular outperforming existing algorithms by an increasing margin as the compression ratio becomes more challenging.

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