视觉注意力有助于在人类视野中的噪音，腐败和分布变化下实现强大的感知，这是现代神经网络仍然缺乏的领域。我们介绍了Vars，来自复发性稀疏重建的视觉注意力，这是一种基于人类视觉注意机制的两个突出特征的新注意力公式：复发性和稀疏性。相关特征通过神经元之间的复发连接组合在一起，而显着物体通过稀疏正则化出现。 VARS采用带有复发连接的吸引子网络，随着时间的流逝，它会收敛到稳定的模式。网络层表示为普通微分方程（ODES），将注意力作为一个经常性吸引子网络表示，该网络等效地使用编码基本数据模式的“模板”字典优化输入的稀疏重建。我们表明，自我注意力是具有单步优化的VAR的特殊情况，没有稀疏性约束。 VAR可以很容易地用作替代流行视觉变形金刚的自我注意力，从而不断提高其在各种基准测试中的稳健性。代码在GitHub（https://github.com/bfshi/vars）上发布。

Recent studies show that Vision Transformers(ViTs) exhibit strong robustness against various corruptions. Although this property is partly attributed to the self-attention mechanism, there is still a lack of systematic understanding. In this paper, we examine the role of self-attention in learning robust representations. Our study is motivated by the intriguing properties of the emerging visual grouping in Vision Transformers, which indicates that self-attention may promote robustness through improved mid-level representations. We further propose a family of fully attentional networks (FANs) that strengthen this capability by incorporating an attentional channel processing design. We validate the design comprehensively on various hierarchical backbones. Our model achieves a state-of-the-art 87.1% accuracy and 35.8% mCE on ImageNet-1k and ImageNet-C with 76.8M parameters. We also demonstrate state-of-the-art accuracy and robustness in two downstream tasks: semantic segmentation and object detection. Code is available at: https://github.com/NVlabs/FAN.

人类自然有效地在复杂的场景中找到突出区域。通过这种观察的动机，引入了计算机视觉中的注意力机制，目的是模仿人类视觉系统的这一方面。这种注意机制可以基于输入图像的特征被视为动态权重调整过程。注意机制在许多视觉任务中取得了巨大的成功，包括图像分类，对象检测，语义分割，视频理解，图像生成，3D视觉，多模态任务和自我监督的学习。在本调查中，我们对计算机愿景中的各种关注机制进行了全面的审查，并根据渠道注意，空间关注，暂时关注和分支注意力进行分类。相关的存储库https：//github.com/menghaoguo/awesome-vision-tions致力于收集相关的工作。我们还建议了未来的注意机制研究方向。

作为现代深度学习的重要成分，关注机制，特别是自我关注，在全球相关发现中起着至关重要的作用。但是，在建模全局背景时，手工制作的注意力不可替代？我们的兴趣发现是自我关注并不优于20年前开发的矩阵分解（MD）模型，了解编码长距离依赖性的性能和计算成本。我们将全局上下文问题模拟为低级别恢复问题，并显示其优化算法可以帮助设计全局信息块。然后，本文提出了一系列汉堡包，其中我们采用了优化算法来解决MD，以将输入表示分解为子矩阵并重建低级别嵌入。具有不同MDS的汉堡包可以在小心地应对通过MDS的梯度时，对流行的全球背景模块自我关注进行。在愿景任务中进行综合实验，在那里学习全球范围至关重要，包括语义分割和图像生成，展示了对自我关注及其变体的显着改善。

Deep neural networks provide unprecedented performance gains in many real world problems in signal and image processing. Despite these gains, future development and practical deployment of deep networks is hindered by their blackbox nature, i.e., lack of interpretability, and by the need for very large training sets. An emerging technique called algorithm unrolling or unfolding offers promise in eliminating these issues by providing a concrete and systematic connection between iterative algorithms that are used widely in signal processing and deep neural networks. Unrolling methods were first proposed to develop fast neural network approximations for sparse coding. More recently, this direction has attracted enormous attention and is rapidly growing both in theoretic investigations and practical applications. The growing popularity of unrolled deep networks is due in part to their potential in developing efficient, high-performance and yet interpretable network architectures from reasonable size training sets. In this article, we review algorithm unrolling for signal and image processing. We extensively cover popular techniques for algorithm unrolling in various domains of signal and image processing including imaging, vision and recognition, and speech processing. By reviewing previous works, we reveal the connections between iterative algorithms and neural networks and present recent theoretical results. Finally, we provide a discussion on current limitations of unrolling and suggest possible future research directions.

Astounding results from Transformer models on natural language tasks have intrigued the vision community to study their application to computer vision problems. Among their salient benefits, Transformers enable modeling long dependencies between input sequence elements and support parallel processing of sequence as compared to recurrent networks e.g., Long short-term memory (LSTM). Different from convolutional networks, Transformers require minimal inductive biases for their design and are naturally suited as set-functions. Furthermore, the straightforward design of Transformers allows processing multiple modalities (e.g., images, videos, text and speech) using similar processing blocks and demonstrates excellent scalability to very large capacity networks and huge datasets. These strengths have led to exciting progress on a number of vision tasks using Transformer networks. This survey aims to provide a comprehensive overview of the Transformer models in the computer vision discipline. We start with an introduction to fundamental concepts behind the success of Transformers i.e., self-attention, large-scale pre-training, and bidirectional feature encoding. We then cover extensive applications of transformers in vision including popular recognition tasks (e.g., image classification, object detection, action recognition, and segmentation), generative modeling, multi-modal tasks (e.g., visual-question answering, visual reasoning, and visual grounding), video processing (e.g., activity recognition, video forecasting), low-level vision (e.g., image super-resolution, image enhancement, and colorization) and 3D analysis (e.g., point cloud classification and segmentation). We compare the respective advantages and limitations of popular techniques both in terms of architectural design and their experimental value. Finally, we provide an analysis on open research directions and possible future works. We hope this effort will ignite further interest in the community to solve current challenges towards the application of transformer models in computer vision.

Continual Learning (CL) is a field dedicated to devise algorithms able to achieve lifelong learning. Overcoming the knowledge disruption of previously acquired concepts, a drawback affecting deep learning models and that goes by the name of catastrophic forgetting, is a hard challenge. Currently, deep learning methods can attain impressive results when the data modeled does not undergo a considerable distributional shift in subsequent learning sessions, but whenever we expose such systems to this incremental setting, performance drop very quickly. Overcoming this limitation is fundamental as it would allow us to build truly intelligent systems showing stability and plasticity. Secondly, it would allow us to overcome the onerous limitation of retraining these architectures from scratch with the new updated data. In this thesis, we tackle the problem from multiple directions. In a first study, we show that in rehearsal-based techniques (systems that use memory buffer), the quantity of data stored in the rehearsal buffer is a more important factor over the quality of the data. Secondly, we propose one of the early works of incremental learning on ViTs architectures, comparing functional, weight and attention regularization approaches and propose effective novel a novel asymmetric loss. At the end we conclude with a study on pretraining and how it affects the performance in Continual Learning, raising some questions about the effective progression of the field. We then conclude with some future directions and closing remarks.

Attention-based neural networks, such as Transformers, have become ubiquitous in numerous applications, including computer vision, natural language processing, and time-series analysis. In all kinds of attention networks, the attention maps are crucial as they encode semantic dependencies between input tokens. However, most existing attention networks perform modeling or reasoning based on representations, wherein the attention maps of different layers are learned separately without explicit interactions. In this paper, we propose a novel and generic evolving attention mechanism, which directly models the evolution of inter-token relationships through a chain of residual convolutional modules. The major motivations are twofold. On the one hand, the attention maps in different layers share transferable knowledge, thus adding a residual connection can facilitate the information flow of inter-token relationships across layers. On the other hand, there is naturally an evolutionary trend among attention maps at different abstraction levels, so it is beneficial to exploit a dedicated convolution-based module to capture this process. Equipped with the proposed mechanism, the convolution-enhanced evolving attention networks achieve superior performance in various applications, including time-series representation, natural language understanding, machine translation, and image classification. Especially on time-series representation tasks, Evolving Attention-enhanced Dilated Convolutional (EA-DC-) Transformer outperforms state-of-the-art models significantly, achieving an average of 17% improvement compared to the best SOTA. To the best of our knowledge, this is the first work that explicitly models the layer-wise evolution of attention maps. Our implementation is available at https://github.com/pkuyym/EvolvingAttention

视觉变压器（VIT）在各种机器视觉问题上表现出令人印象深刻的性能。这些模型基于多头自我关注机制，可以灵活地参加一系列图像修补程序以编码上下文提示。一个重要问题是在给定贴片上参加图像范围内的上下文的这种灵活性是如何促进在自然图像中处理滋扰，例如，严重的闭塞，域移位，空间置换，对抗和天然扰动。我们通过广泛的一组实验来系统地研究了这个问题，包括三个vit家族和具有高性能卷积神经网络（CNN）的比较。我们展示和分析了vit的以下迷恋性质：（a）变压器对严重闭塞，扰动和域移位高度稳健，例如，即使在随机堵塞80％的图像之后，也可以在想象中保持高达60％的前1个精度。内容。 （b）与局部纹理的偏置有抗闭锁的强大性能，与CNN相比，VITS对纹理的偏置显着偏差。当受到适当训练以编码基于形状的特征时，VITS展示与人类视觉系统相当的形状识别能力，以前在文献中无与伦比。 （c）使用VIT来编码形状表示导致准确的语义分割而没有像素级监控的有趣后果。 （d）可以组合从单VIT模型的现成功能，以创建一个功能集合，导致传统和几枪学习范例的一系列分类数据集中的高精度率。我们显示VIT的有效特征是由于自我关注机制可以实现灵活和动态的接受领域。

最近的视觉变压器（VIT）的进步已经证明了其在图像分类中的令人印象深刻的性能，这使其成为卷积神经网络（CNN）的有希望的替代品。与CNN不同，VIT表示作为图像斑块序列的输入图像。 PATCH-WISE输入图像表示提出了以下问题：与CNN相比，当各个输入图像贴片扰乱自然损坏或对抗性扰动时，如何进行VIT vit表现在这项工作中，我们研究了视觉变形金刚的稳健性，以修补扰动。令人惊讶的是，我们发现视觉变压器对自然腐蚀的斑块比CNN更腐蚀，而它们更容易受到对抗性补丁的影响。此外，我们进行广泛的定性和定量实验，以了解修补扰动的鲁棒性。我们透露，Vit对天然腐蚀斑块的更强烈的稳健性以及对抗对抗性斑块的更高脆弱性都是由注意机制引起的。具体而言，注意模型可以通过有效地忽略自然腐蚀斑块来帮助改善视觉变压器的稳健性。然而，当视力变压器被对手攻击时，注意机制可以很容易地愚弄更多地关注对抗扰动的斑块并导致错误。

弱监督的语义分割（WSSS）是具有挑战性的，特别是当使用图像级标签来监督像素级预测时。为了弥合它们的差距，通常生成一个类激活图（CAM）以提供像素级伪标签。卷积神经网络中的凸轮患有部分激活，即，仅激活最多的识别区域。另一方面，基于变压器的方法在探索具有长范围依赖性建模的全球背景下，非常有效，可能会减轻“部分激活”问题。在本文中，我们提出了基于第一变压器的WSSS方法，并介绍了梯度加权元素明智的变压器注意图（GetAn）。 GetaN显示所有特征映射元素的精确激活，跨越变压器层显示对象的不同部分。此外，我们提出了一种激活感知标签完成模块来生成高质量的伪标签。最后，我们将我们的方法纳入了使用双向向上传播的WSS的结束框架。 Pascal VOC和Coco的广泛实验表明，我们的结果通过显着的保证金击败了最先进的端到端方法，并且优于大多数多级方法.M大多数多级方法。

随着视觉变压器（VIT）在各种计算机视觉任务中取得了重大进展，最近的文献提出了各种香草VIT的变体，以提高效率和功效。但是，目前尚不清楚其独特的建筑如何影响鲁棒性对共同的腐败。在本文中，我们首次尝试探究VIT变体之间的稳健性差距，并探索对鲁棒性必不可少的基础设计。通过广泛而严格的基准测试，我们证明了简单的体系结构设计，例如重叠的补丁嵌入和卷积进料前馈网络（FFN）可以促进VIT的稳健性。此外，由于培训对培训的影响很大程度上取决于数据的增强，因此以鲁棒性目的的先前基于CNN的增强策略是否仍然值得研究。我们探索了VIT上的不同数据增强，并验证了对抗性噪声训练是否强大，而傅立叶域增强则不如。基于这些发现，我们引入了一种新颖的条件方法，该方法生成以输入图像为条件的动态增强参数，从而为常见的腐败提供了最新的鲁棒性。

Vision Transformers have shown great promise recently for many vision tasks due to the insightful architecture design and attention mechanism. By revisiting the self-attention responses in Transformers, we empirically observe two interesting issues. First, Vision Transformers present a queryirrelevant behavior at deep layers, where the attention maps exhibit nearly consistent contexts in global scope, regardless of the query patch position (also head-irrelevant). Second, the attention maps are intrinsically sparse, few tokens dominate the attention weights; introducing the knowledge from ConvNets would largely smooth the attention and enhance the performance. Motivated by above observations, we generalize self-attention formulation to abstract a queryirrelevant global context directly and further integrate the global context into convolutions. The resulting model, a Fully Convolutional Vision Transformer (i.e., FCViT), purely consists of convolutional layers and firmly inherits the merits of both attention mechanism and convolutions, including dynamic property, weight sharing, and short- and long-range feature modeling, etc. Experimental results demonstrate the effectiveness of FCViT. With less than 14M parameters, our FCViT-S12 outperforms related work ResT-Lite by 3.7% top1 accuracy on ImageNet-1K. When scaling FCViT to larger models, we still perform better than previous state-of-the-art ConvNeXt with even fewer parameters. FCViT-based models also demonstrate promising transferability to downstream tasks, like object detection, instance segmentation, and semantic segmentation. Codes and models are made available at: https://github.com/ma-xu/FCViT.

由多种自我关注层组成的变压器，对适用于不同数据方式的通用学习原语，包括计算机视觉最新（SOTA）标准准确性的近期突破。什么仍然很大程度上未开发，是他们的稳健性评估和归因。在这项工作中，我们研究了视觉变压器（VIT）对共同腐败和扰动，分布换算和自然对抗例的鲁棒性。我们使用六种不同的多样化想象数据集关于强大的分类，进行vit模型和Sota卷积神经网络（CNNS）的全面性能比较，大转移。通过一系列系统地设计的实验，我们提供了分析，这些分析提供了定量和定性迹象，以解释为什么VITS确实更强大的学习者。例如，对于更少的参数和类似的数据集和预训练组合，VIT在ImageNet-A上给出了28.10％的前1个精度，这是比一位的可比较变体高4.3x。我们对图像掩蔽，傅里叶谱灵敏度和传播的分析，在离散余弦能量谱上揭示了Vit归属于改善鲁棒性的损伤性能。再现我们的实验的代码可在https://git.io/j3vo0上获得。

Vision Transformers (ViTs) have gained significant popularity in recent years and have proliferated into many applications. However, it is not well explored how varied their behavior is under different learning paradigms. We compare ViTs trained through different methods of supervision, and show that they learn a diverse range of behaviors in terms of their attention, representations, and downstream performance. We also discover ViT behaviors that are consistent across supervision, including the emergence of Offset Local Attention Heads. These are self-attention heads that attend to a token adjacent to the current token with a fixed directional offset, a phenomenon that to the best of our knowledge has not been highlighted in any prior work. Our analysis shows that ViTs are highly flexible and learn to process local and global information in different orders depending on their training method. We find that contrastive self-supervised methods learn features that are competitive with explicitly supervised features, and they can even be superior for part-level tasks. We also find that the representations of reconstruction-based models show non-trivial similarity to contrastive self-supervised models. Finally, we show how the "best" layer for a given task varies by both supervision method and task, further demonstrating the differing order of information processing in ViTs.

在本文中，我们基于任何卷积神经网络中中间注意图的弱监督生成机制，并更加直接地披露了注意模块的有效性，以充分利用其潜力。鉴于现有的神经网络配备了任意注意模块，我们介绍了一个元评论家网络，以评估主网络中注意力图的质量。由于我们设计的奖励的离散性，提出的学习方法是在强化学习环境中安排的，在此设置中，注意力参与者和经常性的批评家交替优化，以提供临时注意力表示的即时批评和修订，因此，由于深度强化的注意力学习而引起了人们的关注。 （Dreal）。它可以普遍应用于具有不同类型的注意模块的网络体系结构，并通过最大程度地提高每个单独注意模块产生的最终识别性能的相对增益来促进其表现能力，如类别和实例识别基准的广泛实验所证明的那样。

Patch-based models, e.g., Vision Transformers (ViTs) and Mixers, have shown impressive results on various visual recognition tasks, alternating classic convolutional networks. While the initial patch-based models (ViTs) treated all patches equally, recent studies reveal that incorporating inductive bias like spatiality benefits the representations. However, most prior works solely focused on the location of patches, overlooking the scene structure of images. Thus, we aim to further guide the interaction of patches using the object information. Specifically, we propose OAMixer (object-aware mixing layer), which calibrates the patch mixing layers of patch-based models based on the object labels. Here, we obtain the object labels in unsupervised or weakly-supervised manners, i.e., no additional human-annotating cost is necessary. Using the object labels, OAMixer computes a reweighting mask with a learnable scale parameter that intensifies the interaction of patches containing similar objects and applies the mask to the patch mixing layers. By learning an object-centric representation, we demonstrate that OAMixer improves the classification accuracy and background robustness of various patch-based models, including ViTs, MLP-Mixers, and ConvMixers. Moreover, we show that OAMixer enhances various downstream tasks, including large-scale classification, self-supervised learning, and multi-object recognition, verifying the generic applicability of OAMixer

多层erceptron（MLP），作为出现的第一个神经网络结构，是一个大的击中。但是由硬件计算能力和数据集的大小限制，它一旦沉没了数十年。在此期间，我们目睹了从手动特征提取到带有局部接收领域的CNN的范式转变，以及基于自我关注机制的全球接收领域的变换。今年（2021年），随着MLP混合器的推出，MLP已重新进入敏捷，并吸引了计算机视觉界的广泛研究。与传统的MLP进行比较，它变得更深，但改变了完全扁平化以补丁平整的输入。鉴于其高性能和较少的需求对视觉特定的感应偏见，但社区无法帮助奇迹，将MLP，最简单的结构与全球接受领域，但没有关注，成为一个新的电脑视觉范式吗？为了回答这个问题，本调查旨在全面概述视觉深层MLP模型的最新发展。具体而言，我们从微妙的子模块设计到全局网络结构，我们审查了这些视觉深度MLP。我们比较了不同网络设计的接收领域，计算复杂性和其他特性，以便清楚地了解MLP的开发路径。调查表明，MLPS的分辨率灵敏度和计算密度仍未得到解决，纯MLP逐渐发展朝向CNN样。我们建议，目前的数据量和计算能力尚未准备好接受纯的MLP，并且人工视觉指导仍然很重要。最后，我们提供了开放的研究方向和可能的未来作品的分析。我们希望这项努力能够点燃社区的进一步兴趣，并鼓励目前为神经网络进行更好的视觉量身定制设计。

视觉变压器（VIV）被涌现为图像识别的最先进的架构。虽然最近的研究表明，VITS比卷积对应物更强大，但我们的实验发现，VITS过度依赖于局部特征（例如，滋扰和质地），并且不能充分使用全局背景（例如，形状和结构）。因此，VIT不能概括到分销，现实世界数据。为了解决这一缺陷，我们通过添加由矢量量化编码器产生的离散令牌来向Vit的输入层提出简单有效的架构修改。与标准的连续像素令牌不同，离散令牌在小扰动下不变，并且单独包含较少的信息，这促进了VITS学习不变的全局信息。实验结果表明，在七种想象中的鲁棒性基准中增加了四个架构变体上的离散表示，在七个想象中心坚固的基准中加强了高达12％的鲁棒性，同时保持了在想象成上的性能。

近年来，已经开发了用于图像分类的新型体系结构组件，从变压器中使用的注意力和斑块开始。尽管先前的作品已经分析了建筑成分某些方面对对抗性攻击的鲁棒性，尤其是视觉变形金刚的影响，但对主要因素的理解仍然是有限的。我们比较了几个（非）固定分类器与不同的架构并研究其属性，包括对抗训练对学习特征的解释性和对看不见威胁模型的鲁棒性的影响。从Resnet到Convnext的消融揭示了关键的架构变化，导致$ 10 \％$更高$ \ ell_ \ ell_ \ infty $ bobustness。