Interpretable Deep Attention Prior for Image Restoration and Enhancement

An inductive bias induced by an untrained network architecture has been shown to be effective as a deep image prior (DIP) in solving inverse imaging problems. However, it is still unclear as to what kind of prior is encoded in the network architecture, and the early stopping for the overfitting problem of DIP still remains the challenge. To address this, we introduce an interpretable network that explores self-attention as a deep attention prior (DAP). Specifically, the proposed deep attention prior is formulated as an interpretable optimization problem. A nonlocal self-similarity prior is incorporated into the network architecture by a self-attention mechanism. Each attention map from our proposed DAP reveals how an output value is generated, which leads to a better understanding of the prior. Furthermore, compared to DIP, the proposed DAP regards the single input degraded image as input to reduce the instability, and introduces the mask operation to handle the early stopping problem. Experiments show that the proposed network works as an effective image prior for solving different inverse imaging problems, such as denoising, inpainting, or pansharpening, while also showing potential applications in higher-level processing such as interactive segmentation and selective colorization.