Reference-based Super-resolution (RefSR) approaches have recently been proposed to overcome the ill-posed problem of image super-resolution by providing additional information from a high-resolution image. Multi-reference super-resolution extends this approach by allowing more information to be incorporated. This paper proposes a 2-step-weighting posterior fusion approach to combine the outputs of RefSR models with multiple references. Extensive experiments on the CUFED5 dataset demonstrate that the proposed methods can be applied to various state-of-the-art RefSR models to get a consistent improvement in image quality.

Reference-based image super-resolution (RefSR) is a promising SR branch and has shown great potential in overcoming the limitations of single image super-resolution. While previous state-of-the-art RefSR methods mainly focus on improving the efficacy and robustness of reference feature transfer, it is generally overlooked that a well reconstructed SR image should enable better SR reconstruction for its similar LR images when it is referred to as. Therefore, in this work, we propose a reciprocal learning framework that can appropriately leverage such a fact to reinforce the learning of a RefSR network. Besides, we deliberately design a progressive feature alignment and selection module for further improving the RefSR task. The newly proposed module aligns reference-input images at multi-scale feature spaces and performs reference-aware feature selection in a progressive manner, thus more precise reference features can be transferred into the input features and the network capability is enhanced. Our reciprocal learning paradigm is model-agnostic and it can be applied to arbitrary RefSR models. We empirically show that multiple recent state-of-the-art RefSR models can be consistently improved with our reciprocal learning paradigm. Furthermore, our proposed model together with the reciprocal learning strategy sets new state-of-the-art performances on multiple benchmarks.

当前的深层图像超分辨率（SR）方法试图从下采样的图像或假设简单高斯内核和添加噪声中降解来恢复高分辨率图像。但是，这种简单的图像处理技术代表了降低图像分辨率的现实世界过程的粗略近似。在本文中，我们提出了一个更现实的过程，通过引入新的内核对抗学习超分辨率（KASR）框架来处理现实世界图像SR问题，以降低图像分辨率。在提议的框架中，降解内核和噪声是自适应建模的，而不是明确指定的。此外，我们还提出了一个迭代监督过程和高频选择性目标，以进一步提高模型SR重建精度。广泛的实验验证了对现实数据集中提出的框架的有效性。

Because of the necessity to obtain high-quality images with minimal radiation doses, such as in low-field magnetic resonance imaging, super-resolution reconstruction in medical imaging has become more popular (MRI). However, due to the complexity and high aesthetic requirements of medical imaging, image super-resolution reconstruction remains a difficult challenge. In this paper, we offer a deep learning-based strategy for reconstructing medical images from low resolutions utilizing Transformer and Generative Adversarial Networks (T-GAN). The integrated system can extract more precise texture information and focus more on important locations through global image matching after successfully inserting Transformer into the generative adversarial network for picture reconstruction. Furthermore, we weighted the combination of content loss, adversarial loss, and adversarial feature loss as the final multi-task loss function during the training of our proposed model T-GAN. In comparison to established measures like PSNR and SSIM, our suggested T-GAN achieves optimal performance and recovers more texture features in super-resolution reconstruction of MRI scanned images of the knees and belly.

基于参考的图像超分辨率（REFSR）旨在利用辅助参考（REF）图像为超溶解的低分辨率（LR）图像。最近，RefSR引起了极大的关注，因为它提供了超越单图SR的替代方法。但是，解决REFSR问题有两个关键的挑战：（i）当它们显着不同时，很难匹配LR和Ref图像之间的对应关系； （ii）如何将相关纹理从参考图像转移以补偿LR图像的细节非常具有挑战性。为了解决RefSR的这些问题，本文提出了一个可变形的注意变压器，即DATSR，具有多个尺度，每个尺度由纹理特征编码器（TFE）模块组成，基于参考的可变形注意（RDA）模块和残差功能聚合（RFA）模块。具体而言，TFE首先提取图像转换（例如，亮度）不敏感的LR和REF图像，RDA可以利用多个相关纹理来补偿更多的LR功能信息，而RFA最终汇总了LR功能和相关纹理，以获得更愉快的宜人的质地结果。广泛的实验表明，我们的DATSR在定量和质量上实现了基准数据集上的最新性能。

面部超分辨率（FSR），也称为面部幻觉，其旨在增强低分辨率（LR）面部图像以产生高分辨率（HR）面部图像的分辨率，是特定于域的图像超分辨率问题。最近，FSR获得了相当大的关注，并目睹了深度学习技术的发展炫目。迄今为止，有很少有基于深入学习的FSR的研究摘要。在本次调查中，我们以系统的方式对基于深度学习的FSR方法进行了全面审查。首先，我们总结了FSR的问题制定，并引入了流行的评估度量和损失功能。其次，我们详细说明了FSR中使用的面部特征和流行数据集。第三，我们根据面部特征的利用大致分类了现有方法。在每个类别中，我们从设计原则的一般描述开始，然后概述代表方法，然后讨论其中的利弊。第四，我们评估了一些最先进的方法的表现。第五，联合FSR和其他任务以及与FSR相关的申请大致介绍。最后，我们设想了这一领域进一步的技术进步的前景。在\ URL {https://github.com/junjun-jiang/face-hallucination-benchmark}上有一个策划的文件和资源的策划文件和资源清单

This paper explores the problem of reconstructing high-resolution light field (LF) images from hybrid lenses, including a high-resolution camera surrounded by multiple low-resolution cameras. The performance of existing methods is still limited, as they produce either blurry results on plain textured areas or distortions around depth discontinuous boundaries. To tackle this challenge, we propose a novel end-to-end learning-based approach, which can comprehensively utilize the specific characteristics of the input from two complementary and parallel perspectives. Specifically, one module regresses a spatially consistent intermediate estimation by learning a deep multidimensional and cross-domain feature representation, while the other module warps another intermediate estimation, which maintains the high-frequency textures, by propagating the information of the high-resolution view. We finally leverage the advantages of the two intermediate estimations adaptively via the learned attention maps, leading to the final high-resolution LF image with satisfactory results on both plain textured areas and depth discontinuous boundaries. Besides, to promote the effectiveness of our method trained with simulated hybrid data on real hybrid data captured by a hybrid LF imaging system, we carefully design the network architecture and the training strategy. Extensive experiments on both real and simulated hybrid data demonstrate the significant superiority of our approach over state-of-the-art ones. To the best of our knowledge, this is the first end-to-end deep learning method for LF reconstruction from a real hybrid input. We believe our framework could potentially decrease the cost of high-resolution LF data acquisition and benefit LF data storage and transmission.

我们考虑单个图像超分辨率（SISR）问题，其中基于低分辨率（LR）输入产生高分辨率（HR）图像。最近，生成的对抗性网络（GANS）变得幻觉细节。大多数沿着这条线的方法依赖于预定义的单个LR-intle-hr映射，这对于SISR任务来说是足够灵活的。此外，GaN生成的假细节可能经常破坏整个图像的现实主义。我们通过为Rich-Detail SISR提出最好的伙伴GANS（Beby-GaN）来解决这些问题。放松不变的一对一的约束，我们允许估计的贴片在培训期间动态寻求最佳监督，这有利于产生更合理的细节。此外，我们提出了一种区域感知的对抗性学习策略，指导我们的模型专注于自适应地为纹理区域发电细节。广泛的实验证明了我们方法的有效性。还构建了超高分辨率4K数据集以促进未来的超分辨率研究。

Single image super-resolution is the task of inferring a high-resolution image from a single low-resolution input. Traditionally, the performance of algorithms for this task is measured using pixel-wise reconstruction measures such as peak signal-to-noise ratio (PSNR) which have been shown to correlate poorly with the human perception of image quality. As a result, algorithms minimizing these metrics tend to produce over-smoothed images that lack highfrequency textures and do not look natural despite yielding high PSNR values.We propose a novel application of automated texture synthesis in combination with a perceptual loss focusing on creating realistic textures rather than optimizing for a pixelaccurate reproduction of ground truth images during training. By using feed-forward fully convolutional neural networks in an adversarial training setting, we achieve a significant boost in image quality at high magnification ratios. Extensive experiments on a number of datasets show the effectiveness of our approach, yielding state-of-the-art results in both quantitative and qualitative benchmarks.

最近，深度神经网络（DNNS）在现实世界图像超分辨率（SR）方面取得了重大成功。但是，具有准侵蚀噪声的对抗图像样本可能威胁到深度学习的SR模型。在本文中，我们为现实世界SR提出了一个强大的深度学习框架，该框架随机消除了输入图像或功能的频域中潜在的对抗噪声。理由是，在SR任务上，清洁图像或功能与频域中受攻击的图案不同。观察到现有的对抗攻击通常会为输入图像增加高频噪声，我们引入了一个新型的随机频率掩码模块，该模块可以以随机方式阻止可能包含有害扰动的高频组件。由于频率掩蔽不仅可能会破坏对抗性扰动，而且还会影响干净的图像中的尖锐细节，我们进一步基于图像的频域开发了对抗性样品分类器，以确定是否应用了提出的掩码模块。基于上述想法，我们设计了一个新颖的现实世界图像SR框架，该框架结合了建议的频率掩盖模块和所提出的对抗分类器与现有的超分辨率骨干网络。实验表明，我们所提出的方法对对抗性攻击更加不敏感，并且比现有模型和防御能力更稳定。

在本文中，我们提出了D2C-SR，这是一个新颖的框架，用于实现现实世界图像超级分辨率的任务。作为一个不适的问题，超分辨率相关任务的关键挑战是给定的低分辨率输入可能会有多个预测。大多数基于经典的深度学习方法都忽略了基本事实，缺乏对基础高频分布的明确建模，从而导致结果模糊。最近，一些基于GAN或学习的超分辨率空间的方法可以生成模拟纹理，但不能保证具有低定量性能的纹理的准确性。重新思考这两者，我们以离散形式了解了基本高频细节的分布，并提出了两阶段的管道：分歧阶段到收敛阶段。在发散阶段，我们提出了一个基于树的结构深网作为差异骨干。提出了发散损失，以鼓励基于树的网络产生的结果，以分解可能的高频表示，这是我们对基本高频分布进行离散建模的方式。在收敛阶段，我们分配空间权重以融合这些不同的预测，以获得更准确的细节，以获取最终输出。我们的方法为推理提供了方便的端到端方式。我们对几个现实世界基准进行评估，包括具有X8缩放系数的新提出的D2CrealSR数据集。我们的实验表明，D2C-SR针对最先进的方法实现了更好的准确性和视觉改进，参数编号明显较少，并且我们的D2C结构也可以作为广义结构应用于其他一些方法以获得改进。我们的代码和数据集可在https://github.com/megvii-research/d2c-sr上找到

图像超分辨率（SR）是重要的图像处理方法之一，可改善计算机视野领域的图像分辨率。在过去的二十年中，在超级分辨率领域取得了重大进展，尤其是通过使用深度学习方法。这项调查是为了在深度学习的角度进行详细的调查，对单像超分辨率的最新进展进行详细的调查，同时还将告知图像超分辨率的初始经典方法。该调查将图像SR方法分类为四个类别，即经典方法，基于学习的方法，无监督学习的方法和特定领域的SR方法。我们还介绍了SR的问题，以提供有关图像质量指标，可用参考数据集和SR挑战的直觉。使用参考数据集评估基于深度学习的方法。一些审查的最先进的图像SR方法包括增强的深SR网络（EDSR），周期循环gan（Cincgan），多尺度残留网络（MSRN），Meta残留密度网络（META-RDN） ，反复反射网络（RBPN），二阶注意网络（SAN），SR反馈网络（SRFBN）和基于小波的残留注意网络（WRAN）。最后，这项调查以研究人员将解决SR的未来方向和趋势和开放问题的未来方向和趋势。

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.

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.

最新的多视图多媒体应用程序在高分辨率（HR）视觉体验与存储或带宽约束之间挣扎。因此，本文提出了一个多视图图像超分辨率（MVISR）任务。它旨在增加从同一场景捕获的多视图图像的分辨率。一种解决方案是将图像或视频超分辨率（SR）方法应用于低分辨率（LR）输入视图结果。但是，这些方法无法处理视图之间的大角度转换，并利用所有多视图图像中的信息。为了解决这些问题，我们提出了MVSRNET，该MVSRNET使用几何信息从所有LR多视图中提取尖锐的细节，以支持LR输入视图的SR。具体而言，MVSRNET中提出的几何感知参考合成模块使用几何信息和所有多视图LR图像来合成像素对齐的HR参考图像。然后，提出的动态高频搜索网络完全利用了SR参考图像中的高频纹理细节。关于几个基准测试的广泛实验表明，我们的方法在最新方法上有了显着改善。

突发超级分辨率（SR）提供了从低质量图像恢复丰富细节的可能性。然而，由于实际应用中的低分辨率（LR）图像具有多种复杂和未知的降级，所以现有的非盲（例如，双臂）设计的网络通常导致恢复高分辨率（HR）图像的严重性能下降。此外，处理多重未对准的嘈杂的原始输入也是具有挑战性的。在本文中，我们解决了从现代手持设备获取的原始突发序列重建HR图像的问题。中央观点是一个内核引导策略，可以用两个步骤解决突发SR：内核建模和HR恢复。前者估计来自原始输入的突发内核，而后者基于估计的内核预测超分辨图像。此外，我们引入了内核感知可变形对准模块，其可以通过考虑模糊的前沿而有效地对准原始图像。对综合和现实世界数据集的广泛实验表明，所提出的方法可以在爆发SR问题中对最先进的性能进行。

成功地应用生成的对抗性网络（GaN）以研究感知单个图像超级度（SISR）。然而，GaN经常倾向于产生具有高频率细节的图像与真实的细节不一致。灵感来自传统细节增强算法，我们提出了一种新的先前知识，先前的细节，帮助GaN减轻这个问题并恢复更现实的细节。所提出的方法名为DSRAN，包括良好设计的详细提取算法，用于捕获图像中最重要的高频信息。然后，两种鉴别器分别用于在图像域和细节域修复上进行监督。 DSRGAN通过细节增强方式将恢复的细节合并到最终输出中。 DSRGAN的特殊设计从基于模型的常规算法和数据驱动的深度学习网络中获得了优势。实验结果表明，DSRGAN在感知度量上表现出最先进的SISR方法，并同时达到保真度量的可比结果。在DSRGAN之后，将其他传统的图像处理算法结合到深度学习网络中，以形成基于模型的深SISR。

我们呈现NERF-SR，一种用于高分辨率（HR）新型视图合成的解决方案，主要是低分辨率（LR）输入。我们的方法是基于神经辐射场（NERF）的内置，其预测每点密度和颜色，具有多层的射击。在在任意尺度上产生图像时，NERF与超越观察图像的分辨率努力。我们的关键识别是NERF具有本地之前的，这意味着可以在附近区域传播3D点的预测，并且保持准确。我们首先通过超级采样策略来利用它，该策略在每个图像像素处射击多个光线，这在子像素级别强制了多视图约束。然后，我们表明，NERF-SR可以通过改进网络进一步提高超级采样的性能，该细化网络利用估计的深度来实现HR参考图像上的相关补丁的幻觉。实验结果表明，NERF-SR在合成和现实世界数据集的HR上为新型视图合成产生高质量结果。

单图超分辨率（SISR）的最新方法在从低分辨率（LR）图像产生高分辨率（HR）图像方面表现出了出色的性能。但是，这些方法中的大多数使用合成生成的LR图像显示出它们的优势，并且它们对现实世界图像的推广性通常并不令人满意。在本文中，我们注意针对可靠的超级分辨率（SR）开发的两种著名策略，即基于参考的SR（REFSR）和零摄影SR（ZSSR），并提出了一种综合解决方案，称为参考 - 基于零击SR（RZSR）。遵循ZSSR的原理，我们使用仅从输入图像本身提取的训练样本在测试时间训练特定于图像的SR网络。为了推进ZSSR，我们获得具有丰富纹理和高频细节的参考图像贴片，这些贴片也仅使用跨尺度匹配从输入图像中提取。为此，我们使用深度信息构建了一个内部参考数据集并从数据集中检索参考图像补丁。使用LR贴片及其相应的HR参考贴片，我们训练由非本地注意模块体现的REFSR网络。实验结果证明了与以前的ZSSR方法相比，与其他完全监督的SISR方法相比，所提出的RZSR的优越性与前所未有的图像相比。

We study on image super-resolution (SR), which aims to recover realistic textures from a low-resolution (LR) image. Recent progress has been made by taking high-resolution images as references (Ref), so that relevant textures can be transferred to LR images. However, existing SR approaches neglect to use attention mechanisms to transfer high-resolution (HR) textures from Ref images, which limits these approaches in challenging cases. In this paper, we propose a novel Texture Transformer Network for Image Super-Resolution (TTSR), in which the LR and Ref images are formulated as queries and keys in a transformer, respectively. TTSR consists of four closely-related modules optimized for image generation tasks, including a learnable texture extractor by DNN, a relevance embedding module, a hard-attention module for texture transfer, and a softattention module for texture synthesis. Such a design encourages joint feature learning across LR and Ref images, in which deep feature correspondences can be discovered by attention, and thus accurate texture features can be transferred. The proposed texture transformer can be further stacked in a cross-scale way, which enables texture recovery from different levels (e.g., from 1× to 4× magnification). Extensive experiments show that TTSR achieves significant improvements over state-of-the-art approaches on both quantitative and qualitative evaluations. The source code can be downloaded at https://github.com/ researchmm/TTSR.