  Non-local self-similarity is well-known to be an effective prior for the
image denoising problem. However, little work has been done to incorporate it
in convolutional neural networks, which surpass non-local model-based methods
despite only exploiting local information. In this paper, we propose a novel
end-to-end trainable neural network architecture employing layers based on
graph convolution operations, thereby creating neurons with non-local receptive
fields. The graph convolution operation generalizes the classic convolution to
arbitrary graphs. In this work, the graph is dynamically computed from
similarities among the hidden features of the network, so that the powerful
representation learning capabilities of the network are exploited to uncover
self-similar patterns. We introduce a lightweight Edge-Conditioned Convolution
which addresses vanishing gradient and over-parameterization issues of this
particular graph convolution. Extensive experiments show state-of-the-art
performance with improved qualitative and quantitative results on both
synthetic Gaussian noise and real noise.
