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

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.

相邻帧的比对被认为是视频超分辨率（VSR）中的重要操作。高级VSR模型，包括最新的VSR变形金刚，通常配备精心设计的对齐模块。但是，自我注意机制的进步可能违反了这种常识。在本文中，我们重新考虑了对齐在VSR变压器中的作用，并进行了几种违反直觉的观察。我们的实验表明：（i）VSR变形金刚可以直接利用来自非对齐视频的多帧信息，并且（ii）现有的对齐方法有时对VSR变形金刚有害。这些观察结果表明，我们可以仅通过删除对齐模块并采用更大的注意力窗口来进一步提高VSR变压器的性能。然而，这样的设计将大大增加计算负担，无法处理大型动议。因此，我们提出了一种称为斑块对齐的新的，有效的对准方法，该方法将图像贴片而不是像素对齐。配备贴片对齐的VSR变形金刚可以在多个基准测试上证明最先进的性能。我们的工作提供了有关如何在VSR中使用多帧信息以及如何为不同网络/数据集选择对齐方法的宝贵见解。代码和模型将在https://github.com/xpixelgroup/rethinkvsralignment上发布。

本文报告了NTIRE 2022关于感知图像质量评估（IQA）的挑战，并与CVPR 2022的图像恢复和增强研讨会（NTIRE）研讨会（NTIRE）讲习班的新趋势举行。感知图像处理算法。这些算法的输出图像与传统扭曲具有完全不同的特征，并包含在此挑战中使用的PIP数据集中。这个挑战分为两条曲目，一个类似于以前的NTIRE IQA挑战的全参考IQA轨道，以及一条侧重于No-Reference IQA方法的新曲目。挑战有192和179名注册参与者的两条曲目。在最后的测试阶段，有7和8个参与的团队提交了模型和事实表。几乎所有这些都比现有的IQA方法取得了更好的结果，并且获胜方法可以证明最先进的性能。

超级分辨率（SR）是低级视觉区域的基本和代表任务。通常认为，从SR网络中提取的特征没有特定的语义信息，并且网络只能从输入到输出中学习复杂的非线性映射。我们可以在SR网络中找到任何“语义”吗？在本文中，我们为此问题提供了肯定的答案。通过分析具有维度降低和可视化的特征表示，我们成功地发现了SR网络中的深度语义表示，\ Texit {i.}，深度劣化表示（DDR），其与图像劣化类型和度数相关。我们还揭示了分类和SR网络之间的表示语义的差异。通过广泛的实验和分析，我们得出一系列观测和结论，对未来的工作具有重要意义，例如解释低级CNN网络的内在机制以及开发盲人SR的新评估方法。

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。

edu.hk (a) Image Reconstruction (b) Image Colorization (c) Image Super-Resolution (d) Image Denoising (e) Image Inpainting (f) Semantic Manipulation Figure 1: Multi-code GAN prior facilitates many image processing applications using the reconstruction from fixed PGGAN [23] models.

Figure 1: Manipulating various facial attributes through varying the latent codes of a well-trained GAN model. The first column shows the original synthesis from PGGAN [21], while each of the other columns shows the results of manipulating a specific attribute.

The Super-Resolution Generative Adversarial Network (SR-GAN) [1] is a seminal work that is capable of generating realistic textures during single image super-resolution. However, the hallucinated details are often accompanied with unpleasant artifacts. To further enhance the visual quality, we thoroughly study three key components of SRGANnetwork architecture, adversarial loss and perceptual loss, and improve each of them to derive an Enhanced SRGAN (ESRGAN). In particular, we introduce the Residual-in-Residual Dense Block (RRDB) without batch normalization as the basic network building unit. Moreover, we borrow the idea from relativistic GAN [2] to let the discriminator predict relative realness instead of the absolute value. Finally, we improve the perceptual loss by using the features before activation, which could provide stronger supervision for brightness consistency and texture recovery. Benefiting from these improvements, the proposed ESRGAN achieves consistently better visual quality with more realistic and natural textures than SRGAN and won the first place in the PIRM2018-SR Challenge 1 [3]. The code is available at https://github.com/xinntao/ESRGAN.

Large training data and expensive model tweaking are standard features of deep learning for images. As a result, data owners often utilize cloud resources to develop large-scale complex models, which raises privacy concerns. Existing solutions are either too expensive to be practical or do not sufficiently protect the confidentiality of data and models. In this paper, we study and compare novel \emph{image disguising} mechanisms, DisguisedNets and InstaHide, aiming to achieve a better trade-off among the level of protection for outsourced DNN model training, the expenses, and the utility of data. DisguisedNets are novel combinations of image blocktization, block-level random permutation, and two block-level secure transformations: random multidimensional projection (RMT) and AES pixel-level encryption (AES). InstaHide is an image mixup and random pixel flipping technique \cite{huang20}. We have analyzed and evaluated them under a multi-level threat model. RMT provides a better security guarantee than InstaHide, under the Level-1 adversarial knowledge with well-preserved model quality. In contrast, AES provides a security guarantee under the Level-2 adversarial knowledge, but it may affect model quality more. The unique features of image disguising also help us to protect models from model-targeted attacks. We have done an extensive experimental evaluation to understand how these methods work in different settings for different datasets.