The recurrent structure is a prevalent framework for the task of video super-resolution, which models the temporal dependency between frames via hidden states. When applied to real-world scenarios with unknown and complex degradations, hidden states tend to contain unpleasant artifacts and propagate them to restored frames. In this circumstance, our analyses show that such artifacts can be largely alleviated when the hidden state is replaced with a cleaner counterpart. Based on the observations, we propose a Hidden State Attention (HSA) module to mitigate artifacts in real-world video super-resolution. Specifically, we first adopt various cheap filters to produce a hidden state pool. For example, Gaussian blur filters are for smoothing artifacts while sharpening filters are for enhancing details. To aggregate a new hidden state that contains fewer artifacts from the hidden state pool, we devise a Selective Cross Attention (SCA) module, in which the attention between input features and each hidden state is calculated. Equipped with HSA, our proposed method, namely FastRealVSR, is able to achieve 2x speedup while obtaining better performance than Real-BasicVSR. Codes will be available at https://github.com/TencentARC/FastRealVSR

本文研究了动画视频的现实世界视频超分辨率（VSR）的问题，并揭示了实用动画VSR的三个关键改进。首先，最近的现实世界超分辨率方法通常依赖于使用基本运算符的降解模拟，而没有任何学习能力，例如模糊，噪声和压缩。在这项工作中，我们建议从真正的低质量动画视频中学习此类基本操作员，并将学习的操作员纳入降级生成管道中。这样的基于神经网络的基本操作员可以帮助更好地捕获实际降解的分布。其次，大规模的高质量动画视频数据集AVC构建，以促进动画VSR的全面培训和评估。第三，我们进一步研究了有效的多尺度网络结构。它利用单向复发网络的效率以及基于滑动窗口的方法的有效性。多亏了上述精致的设计，我们的方法Animesr能够有效，有效地恢复现实世界中的低质量动画视频，从而实现优于以前的最先进方法。

Video Super-Resolution (VSR) aims to restore high-resolution (HR) videos from low-resolution (LR) videos. Existing VSR techniques usually recover HR frames by extracting pertinent textures from nearby frames with known degradation processes. Despite significant progress, grand challenges are remained to effectively extract and transmit high-quality textures from high-degraded low-quality sequences, such as blur, additive noises, and compression artifacts. In this work, a novel Frequency-Transformer (FTVSR) is proposed for handling low-quality videos that carry out self-attention in a combined space-time-frequency domain. First, video frames are split into patches and each patch is transformed into spectral maps in which each channel represents a frequency band. It permits a fine-grained self-attention on each frequency band, so that real visual texture can be distinguished from artifacts. Second, a novel dual frequency attention (DFA) mechanism is proposed to capture the global frequency relations and local frequency relations, which can handle different complicated degradation processes in real-world scenarios. Third, we explore different self-attention schemes for video processing in the frequency domain and discover that a ``divided attention'' which conducts a joint space-frequency attention before applying temporal-frequency attention, leads to the best video enhancement quality. Extensive experiments on three widely-used VSR datasets show that FTVSR outperforms state-of-the-art methods on different low-quality videos with clear visual margins. Code and pre-trained models are available at https://github.com/researchmm/FTVSR.

基于常规卷积网络的视频超分辨率（VSR）方法具有很强的视频序列的时间建模能力。然而，在单向反复卷积网络中的不同反复单元接收的输入信息不平衡。早期重建帧接收较少的时间信息，导致模糊或工件效果。虽然双向反复卷积网络可以缓解这个问题，但它大大提高了重建时间和计算复杂性。它也不适用于许多应用方案，例如在线超分辨率。为了解决上述问题，我们提出了一种端到端信息预构建的经常性重建网络（IPRRN），由信息预构建网络（IPNet）和经常性重建网络（RRNET）组成。通过将足够的信息从视频的前面集成来构建初始复发单元所需的隐藏状态，以帮助恢复较早的帧，信息预构建的网络在不向后传播之前和之后的输入信息差异。此外，我们展示了一种紧凑的复发性重建网络，可显着改善恢复质量和时间效率。许多实验已经验证了我们所提出的网络的有效性，并与现有的最先进方法相比，我们的方法可以有效地实现更高的定量和定性评估性能。

现实世界视频超分辨率（VSR）降解的多样性和复杂性构成了推理和培训中的非琐碎挑战。首先，虽然长期繁殖导致在轻度降解的情况下提高性能，但通过传播可以夸大严重的野外降解，损害输出质量。为了平衡细节合成和工件抑制之间的权衡，我们发现在传播之前减少噪声和伪像的图像预清洁阶段。我们的RealBasicVSR配备了精心设计的清洁模块，以质量和效率为现有的现有方法。其次，现实世界的VSR模型通常受到多样化的培训，以提高普遍性，需要增加批量尺寸以产生稳定的梯度。不可避免地，增加的计算负担导致各种问题，包括1）速度 - 性能权衡和2）批量长期权衡。为了缓解第一个权衡，我们提出了一种随机退化计划，可在不牺牲性能的情况下减少高达40％的培训时间。然后，我们分析了不同的训练环境，并建议在训练期间使用更长的序列而不是较大的批次，允许更有效的时间信息使用，导致推论期间的性能更稳定。为了便于公平的比较，我们提出了新的Videolq数据集，其中包含含有丰富纹理和模式的大量现实较低的视频序列。我们的数据集可以作为基准测试的共同点。代码，模型和数据集将公开可用。

Convolutional Neural Network (CNN)-based image super-resolution (SR) has exhibited impressive success on known degraded low-resolution (LR) images. However, this type of approach is hard to hold its performance in practical scenarios when the degradation process is unknown. Despite existing blind SR methods proposed to solve this problem using blur kernel estimation, the perceptual quality and reconstruction accuracy are still unsatisfactory. In this paper, we analyze the degradation of a high-resolution (HR) image from image intrinsic components according to a degradation-based formulation model. We propose a components decomposition and co-optimization network (CDCN) for blind SR. Firstly, CDCN decomposes the input LR image into structure and detail components in feature space. Then, the mutual collaboration block (MCB) is presented to exploit the relationship between both two components. In this way, the detail component can provide informative features to enrich the structural context and the structure component can carry structural context for better detail revealing via a mutual complementary manner. After that, we present a degradation-driven learning strategy to jointly supervise the HR image detail and structure restoration process. Finally, a multi-scale fusion module followed by an upsampling layer is designed to fuse the structure and detail features and perform SR reconstruction. Empowered by such degradation-based components decomposition, collaboration, and mutual optimization, we can bridge the correlation between component learning and degradation modelling for blind SR, thereby producing SR results with more accurate textures. Extensive experiments on both synthetic SR datasets and real-world images show that the proposed method achieves the state-of-the-art performance compared to existing methods.

Existing convolutional neural networks (CNN) based image super-resolution (SR) methods have achieved impressive performance on bicubic kernel, which is not valid to handle unknown degradations in real-world applications. Recent blind SR methods suggest to reconstruct SR images relying on blur kernel estimation. However, their results still remain visible artifacts and detail distortion due to the estimation errors. To alleviate these problems, in this paper, we propose an effective and kernel-free network, namely DSSR, which enables recurrent detail-structure alternative optimization without blur kernel prior incorporation for blind SR. Specifically, in our DSSR, a detail-structure modulation module (DSMM) is built to exploit the interaction and collaboration of image details and structures. The DSMM consists of two components: a detail restoration unit (DRU) and a structure modulation unit (SMU). The former aims at regressing the intermediate HR detail reconstruction from LR structural contexts, and the latter performs structural contexts modulation conditioned on the learned detail maps at both HR and LR spaces. Besides, we use the output of DSMM as the hidden state and design our DSSR architecture from a recurrent convolutional neural network (RCNN) view. In this way, the network can alternatively optimize the image details and structural contexts, achieving co-optimization across time. Moreover, equipped with the recurrent connection, our DSSR allows low- and high-level feature representations complementary by observing previous HR details and contexts at every unrolling time. Extensive experiments on synthetic datasets and real-world images demonstrate that our method achieves the state-of-the-art against existing methods. The source code can be found at https://github.com/Arcananana/DSSR.

如何正确对视频序列中的框架间关系进行建模是视频恢复（VR）的重要挑战。在这项工作中，我们提出了一个无监督的流动对准​​序列模型（S2SVR）来解决此问题。一方面，在VR中首次探讨了在自然语言处理领域的序列到序列模型。优化的序列化建模显示了捕获帧之间远程依赖性的潜力。另一方面，我们为序列到序列模型配备了无监督的光流估计器，以最大程度地发挥其潜力。通过我们提出的无监督蒸馏损失对流量估计器进行了训练，这可以减轻数据差异和以前基于流动的方法的降解光流问题的不准确降解。通过可靠的光流，我们可以在多个帧之间建立准确的对应关系，从而缩小了1D语言和2D未对准框架之间的域差异，并提高了序列到序列模型的潜力。 S2SVR在多个VR任务中显示出卓越的性能，包括视频脱张，视频超分辨率和压缩视频质量增强。代码和模型可在https://github.com/linjing7/vr-baseline上公开获得

现有视频超分辨率（VSR）算法的成功主要是从相邻框架中利用时间信息。但是，这些方法都没有讨论带有固定物体和背景的贴片中时间冗余的影响，并且通常使用相邻框架中的所有信息而没有任何歧视。在本文中，我们观察到时间冗余将对信息传播产生不利影响，这限制了最现有的VSR方法的性能。在这一观察结果的推动下，我们旨在通过以优化的方式处理时间冗余贴片来改善现有的VSR算法。我们开发了两种简单但有效的插件方法，以提高广泛使用的公共视频中现有的本地和非本地传播算法的性能。为了更全面地评估现有VSR算法的鲁棒性和性能，我们还收集了一个新数据集，其中包含各种公共视频作为测试集。广泛的评估表明，所提出的方法可以显着提高野生场景中收集的视频的现有VSR方法的性能，同时保持其在现有常用数据集上的性能。该代码可在https://github.com/hyhsimon/boosted-vsr上找到。

压缩视频超分辨率（VSR）旨在从压缩的低分辨率对应物中恢复高分辨率帧。最近的VSR方法通常通过借用相邻视频帧的相关纹理来增强输入框架。尽管已经取得了一些进展，但是从压缩视频中有效提取和转移高质量纹理的巨大挑战，这些视频通常会高度退化。在本文中，我们提出了一种用于压缩视频超分辨率（FTVSR）的新型频率转换器，该频率在联合时空频域中进行自我注意。首先，我们将视频框架分为斑块，然后将每个贴片转换为DCT光谱图，每个通道代表频带。这样的设计使每个频带都可以进行细粒度的自我注意力，因此可以将真实的视觉纹理与伪影区分开，并进一步用于视频框架修复。其次，我们研究了不同的自我发场方案，并发现在对每个频带上应用暂时关注之前，会引起关节空间的注意力，从而带来最佳的视频增强质量。两个广泛使用的视频超分辨率基准的实验结果表明，FTVSR在未压缩和压缩视频的最先进的方法中都具有清晰的视觉边距。代码可在https://github.com/researchmm/ftvsr上找到。

Video restoration tasks, including super-resolution, deblurring, etc, are drawing increasing attention in the computer vision community. A challenging benchmark named REDS is released in the NTIRE19 Challenge. This new benchmark challenges existing methods from two aspects:(1) how to align multiple frames given large motions, and (2) how to effectively fuse different frames with diverse motion and blur. In this work, we propose a novel Video Restoration framework with Enhanced Deformable convolutions, termed EDVR, to address these challenges. First, to handle large motions, we devise a Pyramid, Cascading and Deformable (PCD) alignment module, in which frame alignment is done at the feature level using deformable convolutions in a coarse-to-fine manner. Second, we propose a Temporal and Spatial Attention (TSA) fusion module, in which attention is applied both temporally and spatially, so as to emphasize important features for subsequent restoration. Thanks to these modules, our EDVR wins the champions and outperforms the second place by a large margin in all four tracks in the NTIRE19 video restoration and enhancement challenges. EDVR also demonstrates superior performance to state-of-the-art published methods on video super-resolution and deblurring. The code is available at https://github.com/xinntao/EDVR.

Face Restoration (FR) aims to restore High-Quality (HQ) faces from Low-Quality (LQ) input images, which is a domain-specific image restoration problem in the low-level computer vision area. The early face restoration methods mainly use statistic priors and degradation models, which are difficult to meet the requirements of real-world applications in practice. In recent years, face restoration has witnessed great progress after stepping into the deep learning era. However, there are few works to study deep learning-based face restoration methods systematically. Thus, this paper comprehensively surveys recent advances in deep learning techniques for face restoration. Specifically, we first summarize different problem formulations and analyze the characteristic of the face image. Second, we discuss the challenges of face restoration. Concerning these challenges, we present a comprehensive review of existing FR methods, including prior based methods and deep learning-based methods. Then, we explore developed techniques in the task of FR covering network architectures, loss functions, and benchmark datasets. We also conduct a systematic benchmark evaluation on representative methods. Finally, we discuss future directions, including network designs, metrics, benchmark datasets, applications,etc. We also provide an open-source repository for all the discussed methods, which is available at https://github.com/TaoWangzj/Awesome-Face-Restoration.

盲人恢复通常会遇到各种规模的面孔输入，尤其是在现实世界中。但是，当前的大多数作品都支持特定的规模面，这限制了其在现实情况下的应用能力。在这项工作中，我们提出了一个新颖的尺度感知盲人面部修复框架，名为FaceFormer，该框架将面部特征恢复作为比例感知转换。所提出的面部特征上采样（FFUP）模块基于原始的比例比例动态生成UPSMPLING滤波器，这有助于我们的网络适应任意面部尺度。此外，我们进一步提出了面部特征嵌入（FFE）模块，该模块利用变压器来层次提取面部潜在的多样性和鲁棒性。因此，我们的脸部形式实现了富裕性和稳健性，恢复了面部的面孔，对面部成分具有现实和对称的细节。广泛的实验表明，我们提出的使用合成数据集训练的方法比当前的最新图像更好地推广到天然低质量的图像。

引导过滤器是计算机视觉和计算机图形中的基本工具，旨在将结构信息从引导图像传输到目标图像。大多数现有方法构造来自指导本身的滤波器内核，而不考虑指导和目标之间的相互依赖性。然而，由于两种图像中通常存在显着不同的边沿，只需将引导的所有结构信息传送到目标即将导致各种伪像。要应对这个问题，我们提出了一个名为Deep Enterponal引导图像过滤的有效框架，其过滤过程可以完全集成两个图像中包含的互补信息。具体地，我们提出了一种注意力内核学习模块，分别从引导和目标生成双组滤波器内核，然后通过在两个图像之间建模像素方向依赖性来自适应地组合它们。同时，我们提出了一种多尺度引导图像滤波模块，以粗略的方式通过所构造的内核逐渐产生滤波结果。相应地，引入了多尺度融合策略以重用中间导点在粗略的过程中。广泛的实验表明，所提出的框架在广泛的引导图像滤波应用中，诸如引导超分辨率，横向模态恢复，纹理拆除和语义分割的最先进的方法。

Video super-resolution (VSR) aiming to reconstruct a high-resolution (HR) video from its low-resolution (LR) counterpart has made tremendous progress in recent years. However, it remains challenging to deploy existing VSR methods to real-world data with complex degradations. On the one hand, there are few well-aligned real-world VSR datasets, especially with large super-resolution scale factors, which limits the development of real-world VSR tasks. On the other hand, alignment algorithms in existing VSR methods perform poorly for real-world videos, leading to unsatisfactory results. As an attempt to address the aforementioned issues, we build a real-world 4 VSR dataset, namely MVSR4$\times$, where low- and high-resolution videos are captured with different focal length lenses of a smartphone, respectively. Moreover, we propose an effective alignment method for real-world VSR, namely EAVSR. EAVSR takes the proposed multi-layer adaptive spatial transform network (MultiAdaSTN) to refine the offsets provided by the pre-trained optical flow estimation network. Experimental results on RealVSR and MVSR4$\times$ datasets show the effectiveness and practicality of our method, and we achieve state-of-the-art performance in real-world VSR task. The dataset and code will be publicly available.

的状态的最先进的视频去模糊方法的成功主要源于潜伏视频恢复相邻帧之间的对准隐式或显式的估计。然而，由于模糊效果的影响，估计从所述模糊的相邻帧的对准信息是不是一个简单的任务。不准确的估计将干扰随后的帧的恢复。相反，估计比对信息，我们提出了一个简单而有效的深层递归神经网络与多尺度双向传播（RNN-MBP），有效传播和收集未对齐的相邻帧的信息，更好的视频去模糊。具体来说，我们建立与这可以通过在不同的尺度整合他们直接利用从非对齐相邻隐藏状态帧间信息的两个U形网RNN细胞多尺度双向传播〜（MBP）模块。此外，为了更好地评估算法和国家的最先进的存在于现实世界的模糊场景的方法，我们也通过一个精心设计的数字视频采集系统创建一个真实世界的模糊视频数据集（RBVD）（的DVA）并把它作为训练和评估数据集。大量的实验结果表明，该RBVD数据集有效地提高了对现实世界的模糊的视频现有算法的性能，并且算法进行从优对三个典型基准的国家的最先进的方法。该代码可在https://github.com/XJTU-CVLAB-LOWLEVEL/RNN-MBP。

视频超分辨率（VSR）是从一系列低分辨率输入序列恢复高分辨率帧的任务。与单图超分辨率不同，VSR可以利用框架的时间信息来重建结果，并提供更多详细信息。最近，随着卷积神经网络（CNN）的快速发展，VSR任务引起了人们的关注，许多基于CNN的方法取得了显着的结果。但是，由于计算资源和运行时限制，只能将一些VSR方法应用于现实世界移动设备。在本文中，我们提出了一个\ textIt {基于滑动窗口的重复网络}（SWRN），该网络可以实时推断，同时仍能达到卓越的性能。具体而言，我们注意到视频帧应该具有可以帮助恢复细节的空间和时间关系，而关键点是如何提取和汇总信息。解决它，我们输入了三个相邻的帧，并利用隐藏状态来重复存储和更新重要的时间信息。我们在REDS数据集上的实验表明，所提出的方法可以很好地适应移动设备并产生视觉上令人愉悦的结果。

时空视频超分辨率（STVSR）的目标是增加低分辨率（LR）和低帧速率（LFR）视频的空间分辨率。基于深度学习的最新方法已取得了重大改进，但是其中大多数仅使用两个相邻帧，即短期功能，可以合成缺失的框架嵌入，这无法完全探索连续输入LR帧的信息流。此外，现有的STVSR模型几乎无法明确利用时间上下文以帮助高分辨率（HR）框架重建。为了解决这些问题，在本文中，我们提出了一个称为STDAN的可变形注意网络。首先，我们设计了一个长短的术语特征插值（LSTFI）模块，该模块能够通过双向RNN结构从更相邻的输入帧中挖掘大量的内容，以进行插值。其次，我们提出了一个空间 - 周期性变形特征聚合（STDFA）模块，其中动态视频框架中的空间和时间上下文被自适应地捕获并汇总以增强SR重建。几个数据集的实验结果表明，我们的方法的表现优于最先进的STVSR方法。该代码可在https://github.com/littlewhitesea/stdan上找到。

Reference-based Super-Resolution (Ref-SR) has recently emerged as a promising paradigm to enhance a low-resolution (LR) input image or video by introducing an additional high-resolution (HR) reference image. Existing Ref-SR methods mostly rely on implicit correspondence matching to borrow HR textures from reference images to compensate for the information loss in input images. However, performing local transfer is difficult because of two gaps between input and reference images: the transformation gap (e.g., scale and rotation) and the resolution gap (e.g., HR and LR). To tackle these challenges, we propose C2-Matching in this work, which performs explicit robust matching crossing transformation and resolution. 1) To bridge the transformation gap, we propose a contrastive correspondence network, which learns transformation-robust correspondences using augmented views of the input image. 2) To address the resolution gap, we adopt teacher-student correlation distillation, which distills knowledge from the easier HR-HR matching to guide the more ambiguous LR-HR matching. 3) Finally, we design a dynamic aggregation module to address the potential misalignment issue between input images and reference images. In addition, to faithfully evaluate the performance of Reference-based Image Super-Resolution under a realistic setting, we contribute the Webly-Referenced SR (WR-SR) dataset, mimicking the practical usage scenario. We also extend C2-Matching to Reference-based Video Super-Resolution task, where an image taken in a similar scene serves as the HR reference image. Extensive experiments demonstrate that our proposed C2-Matching significantly outperforms state of the arts on the standard CUFED5 benchmark and also boosts the performance of video SR by incorporating the C2-Matching component into Video SR pipelines.

深度映射记录场景中的视点和对象之间的距离，这在许多真实应用程序中起着关键作用。然而，消费者级RGB-D相机捕获的深度图遭受了低空间分辨率。引导深度地图超分辨率（DSR）是解决此问题的流行方法，该方法试图从输入的低分辨率（LR）深度及其耦合的HR RGB图像中恢复高分辨率（HR）深度映射和作为指引。引导DSR最具挑战性的问题是如何正确选择一致的结构并传播它们，并正确处理不一致的结构。在本文中，我们提出了一种用于引导DSR的新型关注的分层多模态融合（AHMF）网络。具体地，为了有效地提取和组合来自LR深度和HR引导的相关信息，我们提出了一种基于多模态注意力的融合（MMAF）策略，包括分层卷积层，包括特征增强块，以选择有价值的功能和特征重新校准块来统一不同外观特征的方式的相似性度量。此外，我们提出了一个双向分层特征协作（BHFC）模块，以完全利用多尺度特征之间的低级空间信息和高级结构信息。实验结果表明，在重建精度，运行速度和记忆效率方面，我们的方法优于最先进的方法。