论文标题
何时将卷积神经网络用于反问题
When to Use Convolutional Neural Networks for Inverse Problems
论文作者
论文摘要
计算机视觉中的重建任务从根本上是从一组嘈杂的测量中恢复不确定的信号。例子包括运动的超分辨率,图像降解和非刚性结构,所有这些结构都通过深度学习看到了最近的进步。但是,较早的工作大量使用了稀疏信号重建框架(例如卷积稀疏编码)。尽管这项工作最终被深度学习所超越,但它基于一个更加发达的理论框架。 Papyan等的最新工作。 AL通过显示如何将卷积神经网络(CNN)视为卷积稀疏编码(CSC)问题的近似解决方案,从而提供了两种方法之间的桥梁。在这项工作中,我们认为,对于某些类型的反问题,CNN近似破坏了导致性能差。我们认为,对于这些类型的问题,应使用CSC方法,并用经验证据验证这一论点。具体而言,我们将JPEG伪像减少和非刚性轨迹重建视为CNN的具有挑战性的反问题,并使用CSC方法在其上表现出最先进的性能。此外,我们为该模型及其应用提供了一些实际的改进,还显示了CSC模型中的见解如何使CNN在其幼稚应用失败的任务中有效。
Reconstruction tasks in computer vision aim fundamentally to recover an undetermined signal from a set of noisy measurements. Examples include super-resolution, image denoising, and non-rigid structure from motion, all of which have seen recent advancements through deep learning. However, earlier work made extensive use of sparse signal reconstruction frameworks (e.g convolutional sparse coding). While this work was ultimately surpassed by deep learning, it rested on a much more developed theoretical framework. Recent work by Papyan et. al provides a bridge between the two approaches by showing how a convolutional neural network (CNN) can be viewed as an approximate solution to a convolutional sparse coding (CSC) problem. In this work we argue that for some types of inverse problems the CNN approximation breaks down leading to poor performance. We argue that for these types of problems the CSC approach should be used instead and validate this argument with empirical evidence. Specifically we identify JPEG artifact reduction and non-rigid trajectory reconstruction as challenging inverse problems for CNNs and demonstrate state of the art performance on them using a CSC method. Furthermore, we offer some practical improvements to this model and its application, and also show how insights from the CSC model can be used to make CNNs effective in tasks where their naive application fails.