基于卷积神经网络的单图像超分辨率（SISR）近年来取得了很大进展。然而，由于计算和内存成本，难以将这些方法应用于现实世界场景。同时，如何充分利用中间特征在有限的参数和计算的约束下是一个巨大的挑战。为了减轻这些问题，我们提出了一种轻量级但有效的特征蒸馏交互加权网络（FDIWN）。具体地，FDIWN利用一系列专门设计的特征随机加权组（FSWG）作为骨干，以及几种新的相互宽残留蒸馏相互作用块（WDIB）形成FSWG。另外，将宽相同的残余加权（WIRW）单元和宽卷积残余加权（WCRW）单元引入WDIB以进行更好的特征蒸馏。此外，提出了一种宽残留的蒸馏连接（WRDC）框架和自校准融合（SCF）单元，以更灵活和有效地与不同的尺度相互作用。扩大实验表明，我们的FDIWN优于其他模型来攻击良好的模型模型性能与效率之间的平衡。代码可在https://github.com/iviplab/fdiwn获得。

Recently, great progress has been made in single-image super-resolution (SISR) based on deep learning technology. However, the existing methods usually require a large computational cost. Meanwhile, the activation function will cause some features of the intermediate layer to be lost. Therefore, it is a challenge to make the model lightweight while reducing the impact of intermediate feature loss on the reconstruction quality. In this paper, we propose a Feature Interaction Weighted Hybrid Network (FIWHN) to alleviate the above problem. Specifically, FIWHN consists of a series of novel Wide-residual Distillation Interaction Blocks (WDIB) as the backbone, where every third WDIBs form a Feature shuffle Weighted Group (FSWG) by mutual information mixing and fusion. In addition, to mitigate the adverse effects of intermediate feature loss on the reconstruction results, we introduced a well-designed Wide Convolutional Residual Weighting (WCRW) and Wide Identical Residual Weighting (WIRW) units in WDIB, and effectively cross-fused features of different finenesses through a Wide-residual Distillation Connection (WRDC) framework and a Self-Calibrating Fusion (SCF) unit. Finally, to complement the global features lacking in the CNN model, we introduced the Transformer into our model and explored a new way of combining the CNN and Transformer. Extensive quantitative and qualitative experiments on low-level and high-level tasks show that our proposed FIWHN can achieve a good balance between performance and efficiency, and is more conducive to downstream tasks to solve problems in low-pixel scenarios.

随着深度学习的发展，单图像超分辨率（SISR）取得了重大突破。最近，已经提出了基于全局特征交互的SISR网络性能的方法。但是，需要动态地忽略对上下文的响应的神经元的功能。为了解决这个问题，我们提出了一个轻巧的交叉障碍性推理网络（CFIN），这是一个由卷积神经网络（CNN）和变压器组成的混合网络。具体而言，一种新型的交叉磁场导向变压器（CFGT）旨在通过使用调制卷积内核与局部代表性语义信息结合来自适应修改网络权重。此外，提出了基于CNN的跨尺度信息聚合模块（CIAM），以使模型更好地专注于潜在的实用信息并提高变压器阶段的效率。广泛的实验表明，我们提出的CFIN是一种轻巧有效的SISR模型，可以在计算成本和模型性能之间达到良好的平衡。

具有强大学习能力的CNN被广泛选择以解决超分辨率问题。但是，CNN依靠更深的网络体系结构来提高图像超分辨率的性能，这可能会增加计算成本。在本文中，我们提出了一个增强的超分辨率组CNN（ESRGCNN），具有浅层架构，通过完全融合了深层和宽的通道特征，以在单图超级分辨率中的不同通道的相关性提取更准确的低频信息（ SISR）。同样，ESRGCNN中的信号增强操作对于继承更长途上下文信息以解决长期依赖性也很有用。将自适应上采样操作收集到CNN中，以获得具有不同大小的低分辨率图像的图像超分辨率模型。广泛的实验报告说，我们的ESRGCNN在SISR中的SISR性能，复杂性，执行速度，图像质量评估和SISR的视觉效果方面超过了最先进的实验。代码可在https://github.com/hellloxiaotian/esrgcnn上找到。

Informative features play a crucial role in the single image super-resolution task. Channel attention has been demonstrated to be effective for preserving information-rich features in each layer. However, channel attention treats each convolution layer as a separate process that misses the correlation among different layers. To address this problem, we propose a new holistic attention network (HAN), which consists of a layer attention module (LAM) and a channel-spatial attention module (CSAM), to model the holistic interdependencies among layers, channels, and positions. Specifically, the proposed LAM adaptively emphasizes hierarchical features by considering correlations among layers. Meanwhile, CSAM learns the confidence at all the positions of each channel to selectively capture more informative features. Extensive experiments demonstrate that the proposed HAN performs favorably against the state-ofthe-art single image super-resolution approaches.

Image super-resolution (SR) serves as a fundamental tool for the processing and transmission of multimedia data. Recently, Transformer-based models have achieved competitive performances in image SR. They divide images into fixed-size patches and apply self-attention on these patches to model long-range dependencies among pixels. However, this architecture design is originated for high-level vision tasks, which lacks design guideline from SR knowledge. In this paper, we aim to design a new attention block whose insights are from the interpretation of Local Attribution Map (LAM) for SR networks. Specifically, LAM presents a hierarchical importance map where the most important pixels are located in a fine area of a patch and some less important pixels are spread in a coarse area of the whole image. To access pixels in the coarse area, instead of using a very large patch size, we propose a lightweight Global Pixel Access (GPA) module that applies cross-attention with the most similar patch in an image. In the fine area, we use an Intra-Patch Self-Attention (IPSA) module to model long-range pixel dependencies in a local patch, and then a $3\times3$ convolution is applied to process the finest details. In addition, a Cascaded Patch Division (CPD) strategy is proposed to enhance perceptual quality of recovered images. Extensive experiments suggest that our method outperforms state-of-the-art lightweight SR methods by a large margin. Code is available at https://github.com/passerer/HPINet.

Convolutional neural network (CNN) depth is of crucial importance for image super-resolution (SR). However, we observe that deeper networks for image SR are more difficult to train. The lowresolution inputs and features contain abundant low-frequency information, which is treated equally across channels, hence hindering the representational ability of CNNs. To solve these problems, we propose the very deep residual channel attention networks (RCAN). Specifically, we propose a residual in residual (RIR) structure to form very deep network, which consists of several residual groups with long skip connections. Each residual group contains some residual blocks with short skip connections. Meanwhile, RIR allows abundant low-frequency information to be bypassed through multiple skip connections, making the main network focus on learning high-frequency information. Furthermore, we propose a channel attention mechanism to adaptively rescale channel-wise features by considering interdependencies among channels. Extensive experiments show that our RCAN achieves better accuracy and visual improvements against state-of-the-art methods.

卷积神经网络在过去十年中允许在单个图像超分辨率（SISR）中的显着进展。在SISR最近的进展中，关注机制对于高性能SR模型至关重要。但是，注意机制仍然不清楚为什么它在SISR中的工作原理。在这项工作中，我们试图量化和可视化SISR中的注意力机制，并表明并非所有关注模块都同样有益。然后，我们提出了关注网络（A $ ^ 2 $ n）的注意力，以获得更高效和准确的SISR。具体来说，$ ^ 2 $ n包括非关注分支和耦合注意力分支。提出了一种动态注意力模块，为这两个分支产生权重，以动态地抑制不需要的注意力调整，其中权重根据输入特征自适应地改变。这允许注意模块专门从事惩罚的有益实例，从而大大提高了注意力网络的能力，即几个参数开销。实验结果表明，我们的最终模型A $ ^ 2 $ n可以实现与类似尺寸的最先进网络相比的卓越的权衡性能。代码可以在https://github.com/haoyuc/a2n获得。

卷积神经网络（CNN）通过深度体系结构获得了出色的性能。但是，这些CNN在复杂的场景下通常对图像超分辨率（SR）实现较差的鲁棒性。在本文中，我们通过利用不同类型的结构信息来获得高质量图像，提出了异质组SR CNN（HGSRCNN）。具体而言，HGSRCNN的每个异质组块（HGB）都采用含有对称组卷积块和互补的卷积块的异质体系结构，并以平行方式增强不同渠道的内部和外部关系，以促进富裕类型的较富裕类型的信息， 。为了防止出现获得的冗余功能，以串行方式具有信号增强功能的完善块旨在过滤无用的信息。为了防止原始信息的丢失，多级增强机制指导CNN获得对称架构，以促进HGSRCNN的表达能力。此外，开发了一种平行的向上采样机制来训练盲目的SR模型。广泛的实验表明，在定量和定性分析方面，提出的HGSRCNN获得了出色的SR性能。可以在https://github.com/hellloxiaotian/hgsrcnn上访问代码。

Convolutional neural network (CNN) has achieved great success on image super-resolution (SR). However, most deep CNN-based SR models take massive computations to obtain high performance. Downsampling features for multi-resolution fusion is an efficient and effective way to improve the performance of visual recognition. Still, it is counter-intuitive in the SR task, which needs to project a low-resolution input to high-resolution. In this paper, we propose a novel Hybrid Pixel-Unshuffled Network (HPUN) by introducing an efficient and effective downsampling module into the SR task. The network contains pixel-unshuffled downsampling and Self-Residual Depthwise Separable Convolutions. Specifically, we utilize pixel-unshuffle operation to downsample the input features and use grouped convolution to reduce the channels. Besides, we enhance the depthwise convolution's performance by adding the input feature to its output. Experiments on benchmark datasets show that our HPUN achieves and surpasses the state-of-the-art reconstruction performance with fewer parameters and computation costs.

从深度学习的迅速发展中受益，许多基于CNN的图像超分辨率方法已经出现并取得了更好的结果。但是，大多数算法很难同时适应空间区域和通道特征，更不用说它们之间的信息交换了。此外，注意力模块之间的信息交换对于研究人员而言甚至不太明显。为了解决这些问题，我们提出了一个轻量级的空间通道自适应协调，对多级改进增强网络（MREN）。具体而言，我们构建了一个空间通道自适应协调块，该块使网络能够在不同的接受场下学习空间区域和渠道特征感兴趣的信息。此外，在空间部分和通道部分之间的相应特征处理级别的信息在跳跃连接的帮助下交换，以实现两者之间的协调。我们通过简单的线性组合操作在注意模块之间建立了通信桥梁，以便更准确，连续地指导网络注意感兴趣的信息。在几个标准测试集上进行的广泛实验表明，我们的MREN在具有很少数量的参数和非常低的计算复杂性的其他高级算法上实现了优越的性能。

A very deep convolutional neural network (CNN) has recently achieved great success for image super-resolution (SR) and offered hierarchical features as well. However, most deep CNN based SR models do not make full use of the hierarchical features from the original low-resolution (LR) images, thereby achieving relatively-low performance. In this paper, we propose a novel residual dense network (RDN) to address this problem in image SR. We fully exploit the hierarchical features from all the convolutional layers. Specifically, we propose residual dense block (RDB) to extract abundant local features via dense connected convolutional layers. RDB further allows direct connections from the state of preceding RDB to all the layers of current RDB, leading to a contiguous memory (CM) mechanism. Local feature fusion in RDB is then used to adaptively learn more effective features from preceding and current local features and stabilizes the training of wider network. After fully obtaining dense local features, we use global feature fusion to jointly and adaptively learn global hierarchical features in a holistic way. Experiments on benchmark datasets with different degradation models show that our RDN achieves favorable performance against state-of-the-art methods.

随着卷积神经网络最近的大规模发展，已经提出了用于边缘设备上实用部署的大量基于CNN的显着图像超分辨率方法。但是，大多数现有方法都集中在一个特定方面：网络或损失设计，这导致难以最大程度地减少模型大小。为了解决这个问题，我们得出结论，设计，架构搜索和损失设计，以获得更有效的SR结构。在本文中，我们提出了一个名为EFDN的边缘增强功能蒸馏网络，以保留在约束资源下的高频信息。详细说明，我们基于现有的重新处理方法构建了一个边缘增强卷积块。同时，我们提出了边缘增强的梯度损失，以校准重新分配的路径训练。实验结果表明，我们的边缘增强策略可以保持边缘并显着提高最终恢复质量。代码可在https://github.com/icandle/efdn上找到。

Single Image Super-Resolution (SISR) tasks have achieved significant performance with deep neural networks. However, the large number of parameters in CNN-based met-hods for SISR tasks require heavy computations. Although several efficient SISR models have been recently proposed, most are handcrafted and thus lack flexibility. In this work, we propose a novel differentiable Neural Architecture Search (NAS) approach on both the cell-level and network-level to search for lightweight SISR models. Specifically, the cell-level search space is designed based on an information distillation mechanism, focusing on the combinations of lightweight operations and aiming to build a more lightweight and accurate SR structure. The network-level search space is designed to consider the feature connections among the cells and aims to find which information flow benefits the cell most to boost the performance. Unlike the existing Reinforcement Learning (RL) or Evolutionary Algorithm (EA) based NAS methods for SISR tasks, our search pipeline is fully differentiable, and the lightweight SISR models can be efficiently searched on both the cell-level and network-level jointly on a single GPU. Experiments show that our methods can achieve state-of-the-art performance on the benchmark datasets in terms of PSNR, SSIM, and model complexity with merely 68G Multi-Adds for $\times 2$ and 18G Multi-Adds for $\times 4$ SR tasks.

通过利用大型内核分解和注意机制，卷积神经网络（CNN）可以在许多高级计算机视觉任务中与基于变压器的方法竞争。但是，由于远程建模的优势，具有自我注意力的变压器仍然主导着低级视野，包括超分辨率任务。在本文中，我们提出了一个基于CNN的多尺度注意网络（MAN），该网络由多尺度的大内核注意力（MLKA）和一个封闭式的空间注意单元（GSAU）组成，以提高卷积SR网络的性能。在我们的MLKA中，我们使用多尺度和栅极方案纠正LKA，以在各种粒度水平上获得丰富的注意图，从而共同汇总了全局和局部信息，并避免了潜在的阻塞伪像。在GSAU中，我们集成了栅极机制和空间注意力，以消除不必要的线性层和汇总信息丰富的空间环境。为了确认我们的设计的有效性，我们通过简单地堆叠不同数量的MLKA和GSAU来评估具有多种复杂性的人。实验结果表明，我们的人可以在最先进的绩效和计算之间实现各种权衡。代码可从https://github.com/icandle/man获得。

Recently, deep convolutional neural networks (CNNs) have been widely explored in single image super-resolution (SISR) and obtained remarkable performance. However, most of the existing CNN-based SISR methods mainly focus on wider or deeper architecture design, neglecting to explore the feature correlations of intermediate layers, hence hindering the representational power of CNNs. To address this issue, in this paper, we propose a second-order attention network (SAN) for more powerful feature expression and feature correlation learning. Specifically, a novel trainable second-order channel attention (SOCA) module is developed to adaptively rescale the channel-wise features by using second-order feature statistics for more discriminative representations. Furthermore, we present a non-locally enhanced residual group (NLRG) structure, which not only incorporates non-local operations to capture long-distance spatial contextual information, but also contains repeated local-source residual attention groups (LSRAG) to learn increasingly abstract feature representations. Experimental results demonstrate the superiority of our SAN network over state-of-the-art SISR methods in terms of both quantitative metrics and visual quality.

在恶劣天气下的图像修复是一项艰巨的任务。过去的大多数作品都集中在消除图像中的雨水和阴霾现象。但是，雪也是一种极为普遍的大气现象，它将严重影响高级计算机视觉任务的性能，例如对象检测和语义分割。最近，已经提出了一些用于降雪的方法，大多数方法直接将雪图像作为优化对象。但是，雪地点和形状的分布很复杂。因此，未能有效地检测雪花 /雪连胜将影响降雪并限制模型性能。为了解决这些问题，我们提出了一个雪地掩模的自适应残留网络（SMGARN）。具体而言，SMGARN由三个部分组成，即Mask-Net，Guidance-Fusion Network（GF-NET）和重建-NET。首先，我们构建了一个以自像素的注意（SA）和跨像素的注意（CA），以捕获雪花的特征并准确地定位了雪的位置，从而预测了准确的雪山。其次，预测的雪面被发送到专门设计的GF-NET中，以适应指导模型去除雪。最后，使用有效的重建网络来消除面纱效果并纠正图像以重建最终的无雪图像。广泛的实验表明，我们的SMGARN数值优于所有现有的降雪方法，并且重建的图像在视觉对比度上更清晰。所有代码都将可用。

使用注意机制的深度卷积神经网络（CNN）在动态场景中取得了巨大的成功。在大多数这些网络中，只能通过注意图精炼的功能传递到下一层，并且不同层的注意力图彼此分开，这并不能充分利用来自CNN中不同层的注意信息。为了解决这个问题，我们引入了一种新的连续跨层注意传播（CCLAT）机制，该机制可以利用所有卷积层的分层注意信息。基于CCLAT机制，我们使用非常简单的注意模块来构建一个新型残留的密集注意融合块（RDAFB）。在RDAFB中，从上述RDAFB的输出中推断出的注意图和每一层直接连接到后续的映射，从而导致CRLAT机制。以RDAFB为基础，我们为动态场景Deblurring设计了一个名为RDAFNET的有效体系结构。基准数据集上的实验表明，所提出的模型的表现优于最先进的脱毛方法，并证明了CCLAT机制的有效性。源代码可在以下网址提供：https：//github.com/xjmz6/rdafnet。

In recent years, deep learning methods have been successfully applied to single-image super-resolution tasks. Despite their great performances, deep learning methods cannot be easily applied to realworld applications due to the requirement of heavy computation. In this paper, we address this issue by proposing an accurate and lightweight deep network for image super-resolution. In detail, we design an architecture that implements a cascading mechanism upon a residual network. We also present variant models of the proposed cascading residual network to further improve efficiency. Our extensive experiments show that even with much fewer parameters and operations, our models achieve performance comparable to that of state-of-the-art methods.

Recently, Transformer-based image restoration networks have achieved promising improvements over convolutional neural networks due to parameter-independent global interactions. To lower computational cost, existing works generally limit self-attention computation within non-overlapping windows. However, each group of tokens are always from a dense area of the image. This is considered as a dense attention strategy since the interactions of tokens are restrained in dense regions. Obviously, this strategy could result in restricted receptive fields. To address this issue, we propose Attention Retractable Transformer (ART) for image restoration, which presents both dense and sparse attention modules in the network. The sparse attention module allows tokens from sparse areas to interact and thus provides a wider receptive field. Furthermore, the alternating application of dense and sparse attention modules greatly enhances representation ability of Transformer while providing retractable attention on the input image.We conduct extensive experiments on image super-resolution, denoising, and JPEG compression artifact reduction tasks. Experimental results validate that our proposed ART outperforms state-of-the-art methods on various benchmark datasets both quantitatively and visually. We also provide code and models at the website https://github.com/gladzhang/ART.