Path-Restore: Learning Network Path Selection for Image Restoration
This addresses the problem of high computational costs in image restoration for practical applications, offering an incremental improvement in efficiency.
The paper tackles the computational burden of deep CNNs for image restoration by proposing Path-Restore, a multi-path CNN that dynamically selects routes for different image regions, achieving comparable or superior performance with less cost, such as running 2.7x faster than RIDNet on a noise dataset.
Very deep Convolutional Neural Networks (CNNs) have greatly improved the performance on various image restoration tasks. However, this comes at a price of increasing computational burden, hence limiting their practical usages. We observe that some corrupted image regions are inherently easier to restore than others since the distortion and content vary within an image. To leverage this, we propose Path-Restore, a multi-path CNN with a pathfinder that can dynamically select an appropriate route for each image region. We train the pathfinder using reinforcement learning with a difficulty-regulated reward. This reward is related to the performance, complexity and "the difficulty of restoring a region". A policy mask is further investigated to jointly process all the image regions. We conduct experiments on denoising and mixed restoration tasks. The results show that our method achieves comparable or superior performance to existing approaches with less computational cost. In particular, Path-Restore is effective for real-world denoising, where the noise distribution varies across different regions on a single image. Compared to the state-of-the-art RIDNet, our method achieves comparable performance and runs 2.7x faster on the realistic Darmstadt Noise Dataset.