FilterNet: Adaptive Information Filtering Network for Accurate and Fast Image Super-Resolution

Deep convolutional neural network (CNN) approaches have achieved impressive performance for image superresolution (SR). The main issue of image SR is to effectively recover the high-frequency detail of low-resolution (LR) input. However, existing CNN methods often inevitably exhibit a large amount of memory consumption and computational cost. In addition, in most SR networks, the low-frequency and highfrequency components of LR features are treated equally in the training process, which can ignore the local detailed information and hinder the representational capacity of networks. To solve these issues, in this paper, we propose a deep adaptive information filtering network (FilterNet) for accurate and fast image SR. In contrast to existing methods that adopt fully CNN methods to directly predict the HR images, the proposed FilterNet concentrates on more useful features and adaptively filters the redundant low-frequency information. In general, we present the dilated residual group (DRG), which consists of multiple dilated residual units. The DRGs can directly expand the receptive field of the network to efficiently exploit the contextual information of the LR input. In the dilated residual unit, a gated selective mechanism is proposed to adaptively learn more high-frequency information and filter the low-frequency information. Besides, we introduce a novel adaptive information fusion structure, which builds long scaling skip connections among the DRGs to rescale the hierarchical features and fuse more detailed information. The scaling weights can be deemed as the part parameters of our network and trained adaptively. Extensive evaluations on benchmark datasets demonstrate that our FilterNet achieves superior performance both on accuracy and speed compared to recent state-of-the-art methods.