Pretraining is a dominant paradigm in computer vision. Generally, supervised ImageNet pretraining is commonly used to initialize the backbones of person re-identification (Re-ID) models. However, recent works show a surprising result that CNN-based pretraining on ImageNet has limited impacts on Re-ID system due to the large domain gap between ImageNet and person Re-ID data. To seek an alternative to traditional pretraining, here we investigate semantic-based pretraining as another method to utilize additional textual data against ImageNet pretraining. Specifically, we manually construct a diversified FineGPR-C caption dataset for the first time on person Re-ID events. Based on it, a pure semantic-based pretraining approach named VTBR is proposed to adopt dense captions to learn visual representations with fewer images. We train convolutional neural networks from scratch on the captions of FineGPR-C dataset, and then transfer them to downstream Re-ID tasks. Comprehensive experiments conducted on benchmark datasets show that our VTBR can achieve competitive performance compared with ImageNet pretraining - despite using up to 1.4x fewer images, revealing its potential in Re-ID pretraining.

Person re-identification plays a significant role in realistic scenarios due to its various applications in public security and video surveillance. Recently, leveraging the supervised or semi-unsupervised learning paradigms, which benefits from the large-scale datasets and strong computing performance, has achieved a competitive performance on a specific target domain. However, when Re-ID models are directly deployed in a new domain without target samples, they always suffer from considerable performance degradation and poor domain generalization. To address this challenge, we propose a Deep Multimodal Fusion network to elaborate rich semantic knowledge for assisting in representation learning during the pre-training. Importantly, a multimodal fusion strategy is introduced to translate the features of different modalities into the common space, which can significantly boost generalization capability of Re-ID model. As for the fine-tuning stage, a realistic dataset is adopted to fine-tune the pre-trained model for better distribution alignment with real-world data. Comprehensive experiments on benchmarks demonstrate that our method can significantly outperform previous domain generalization or meta-learning methods with a clear margin. Our source code will also be publicly available at https://github.com/JeremyXSC/DMF.

人重新识别（RE-ID）在公共安全和视频监控等应用中起着重要作用。最近，从合成数据引擎的普及中获益的合成数据学习，从公众眼中引起了极大的关注。但是，现有数据集数量，多样性和变性有限，并且不能有效地用于重新ID问题。为了解决这一挑战，我们手动构造一个名为FineGPR的大型人数据集，具有细粒度的属性注释。此外，旨在充分利用FineGPR的潜力，并推广从数百万综合数据的高效培训，我们提出了一个名为AOST的属性分析流水线，它动态地学习了真实域中的属性分布，然后消除了合成和现实世界之间的差距因此，自由地部署到新场景。在基准上进行的实验表明，FineGPR具有AOST胜过（或与）现有的实际和合成数据集，这表明其对重新ID任务的可行性，并证明了众所周知的较少的原则。我们的Synthetic FineGPR数据集可公开可用于\ URL {https://github.com/jeremyxsc/finegpr}。

The de-facto approach to many vision tasks is to start from pretrained visual representations, typically learned via supervised training on ImageNet. Recent methods have explored unsupervised pretraining to scale to vast quantities of unlabeled images. In contrast, we aim to learn high-quality visual representations from fewer images. To this end we revisit supervised pretraining, and seek dataefficient alternatives to classification-based pretraining. We propose VirTex -a pretraining approach using semantically dense captions to learn visual representations. We train convolutional networks from scratch on COCO Captions, and transfer them to downstream recognition tasks including image classification, object detection, and instance segmentation. On all tasks, VirTex yields features that match or exceed those learned on ImageNet -supervised or unsupervised -despite using up to ten times fewer images.

近年来，随着对公共安全的需求越来越多，智能监测网络的快速发展，人员重新识别（RE-ID）已成为计算机视野领域的热门研究主题之一。人员RE-ID的主要研究目标是从不同的摄像机中检索具有相同身份的人。但是，传统的人重新ID方法需要手动标记人的目标，这消耗了大量的劳动力成本。随着深度神经网络的广泛应用，出现了许多基于深入的基于学习的人物的方法。因此，本文促进研究人员了解最新的研究成果和该领域的未来趋势。首先，我们总结了对几个最近公布的人的研究重新ID调查，并补充了系统地分类基于深度学习的人的重新ID方法的最新研究方法。其次，我们提出了一种多维分类，根据度量标准和表示学习，将基于深度学习的人的重新ID方法分为四类，包括深度度量学习，本地特征学习，生成的对抗学习和序列特征学习的方法。此外，我们根据其方法和动机来细分以上四类，讨论部分子类别的优缺点。最后，我们讨论了一些挑战和可能的研究方向的人重新ID。

Person re-identification (Re-ID) aims at retrieving a person of interest across multiple non-overlapping cameras. With the advancement of deep neural networks and increasing demand of intelligent video surveillance, it has gained significantly increased interest in the computer vision community. By dissecting the involved components in developing a person Re-ID system, we categorize it into the closed-world and open-world settings. The widely studied closed-world setting is usually applied under various research-oriented assumptions, and has achieved inspiring success using deep learning techniques on a number of datasets. We first conduct a comprehensive overview with in-depth analysis for closed-world person Re-ID from three different perspectives, including deep feature representation learning, deep metric learning and ranking optimization. With the performance saturation under closed-world setting, the research focus for person Re-ID has recently shifted to the open-world setting, facing more challenging issues. This setting is closer to practical applications under specific scenarios. We summarize the open-world Re-ID in terms of five different aspects. By analyzing the advantages of existing methods, we design a powerful AGW baseline, achieving state-of-the-art or at least comparable performance on twelve datasets for FOUR different Re-ID tasks. Meanwhile, we introduce a new evaluation metric (mINP) for person Re-ID, indicating the cost for finding all the correct matches, which provides an additional criteria to evaluate the Re-ID system for real applications. Finally, some important yet under-investigated open issues are discussed.

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.

随着图像文本对的大量数据以及视觉和语言（V＆L）任务的多样性，学者在该研究领域引入了大量的深度学习模型。此外，近年来，转移学习还显示出在计算机愿景中的巨大成功，例如图像分类，对象检测等以及在自然语言处理中以进行问答，机器翻译等的自然语言处理。继承转移学习的精神， V＆L的研究工作已经在大规模数据集上设计了多种预训练技术，以增强下游任务的性能。本文的目的是提供当代V＆L预审前模型的全面修订。特别是，我们对预处理的方法进行了分类和描述，以及最先进的视觉和语言预训练模型的摘要。此外，还提供了培训数据集和下游任务的列表，以进一步提高V＆L预处理的观点。最后，我们决定采取进一步的一步，讨论众多未来研究的方向。

连接视觉和语言在生成智能中起着重要作用。因此，已经致力于图像标题的大型研究工作，即用句法和语义有意义的句子描述图像。从2015年开始，该任务通常通过由Visual Encoder组成的管道和文本生成的语言模型来解决任务。在这些年来，两种组件通过对象区域，属性，介绍多模态连接，完全关注方法和伯特早期融合策略的利用而显着发展。但是，无论令人印象深刻的结果，图像标题的研究还没有达到结论性答案。这项工作旨在提供图像标题方法的全面概述，从视觉编码和文本生成到培训策略，数据集和评估度量。在这方面，我们量化地比较了许多相关的最先进的方法来确定架构和培训策略中最有影响力的技术创新。此外，讨论了问题的许多变体及其开放挑战。这项工作的最终目标是作为理解现有文献的工具，并突出显示计算机视觉和自然语言处理的研究领域的未来方向可以找到最佳的协同作用。

In this paper, we are interested in learning a generalizable person re-identification (re-ID) representation from unlabeled videos. Compared with 1) the popular unsupervised re-ID setting where the training and test sets are typically under the same domain, and 2) the popular domain generalization (DG) re-ID setting where the training samples are labeled, our novel scenario combines their key challenges: the training samples are unlabeled, and collected form various domains which do no align with the test domain. In other words, we aim to learn a representation in an unsupervised manner and directly use the learned representation for re-ID in novel domains. To fulfill this goal, we make two main contributions: First, we propose Cycle Association (CycAs), a scalable self-supervised learning method for re-ID with low training complexity; and second, we construct a large-scale unlabeled re-ID dataset named LMP-video, tailored for the proposed method. Specifically, CycAs learns re-ID features by enforcing cycle consistency of instance association between temporally successive video frame pairs, and the training cost is merely linear to the data size, making large-scale training possible. On the other hand, the LMP-video dataset is extremely large, containing 50 million unlabeled person images cropped from over 10K Youtube videos, therefore is sufficient to serve as fertile soil for self-supervised learning. Trained on LMP-video, we show that CycAs learns good generalization towards novel domains. The achieved results sometimes even outperform supervised domain generalizable models. Remarkably, CycAs achieves 82.2% Rank-1 on Market-1501 and 49.0% Rank-1 on MSMT17 with zero human annotation, surpassing state-of-the-art supervised DG re-ID methods. Moreover, we also demonstrate the superiority of CycAs under the canonical unsupervised re-ID and the pretrain-and-finetune scenarios.

最近，跨模式的预训练任务一直是一个热点，因为它在各种下文研究中广泛应用，包括检索，字幕，问题答案等。然而，退出的方法采用单媒体预训练模型来探索进行跨模式检索的联合视觉表示，这很容易遭受计算爆炸的影响。此外，尽管常规的双流结构非常有效，但它们仍然缺乏重要的跨模式相互作用，导致性能低。在这些挑战的激励下，我们提出了一个对比的跨模式知识共享预训练（Cookie），以掌握联合文本图像表示。从结构上讲，Cookie由于可接受的时间消耗而采用了传统的双流结构。为了克服上述双流结构的固有缺陷，我们精心设计了两个有效的模块。具体而言，第一个模块是一个体重共享的变压器，它构建在视觉和文本编码器的头上，旨在将语义对齐文本和图像对齐。该设计使视觉和文本路径集中在相同的语义上。另一个是三个专门设计的对比学习，旨在分享不同模型之间的知识。共享的跨模式知识大大发展了单峰表示的研究，从而促进了单模式检索任务。对多模式匹配研究的广泛实验结果，包括跨模式检索，文本匹配和图像检索揭示了我们的计算效率和我们预训练模型的统计指标的上级。

细粒度的图像分析（FGIA）是计算机视觉和模式识别中的长期和基本问题，并为一组多种现实世界应用提供了基础。 FGIA的任务是从属类别分析视觉物体，例如汽车或汽车型号的种类。细粒度分析中固有的小阶级和阶级阶级内变异使其成为一个具有挑战性的问题。利用深度学习的进步，近年来，我们在深入学习动力的FGIA中见证了显着进展。在本文中，我们对这些进展的系统进行了系统的调查，我们试图通过巩固两个基本的细粒度研究领域 - 细粒度的图像识别和细粒度的图像检索来重新定义和扩大FGIA领域。此外，我们还审查了FGIA的其他关键问题，例如公开可用的基准数据集和相关域的特定于应用程序。我们通过突出几个研究方向和开放问题，从社区中突出了几个研究方向和开放问题。

计算机视觉任务可以从估计突出物区域和这些对象区域之间的相互作用中受益。识别对象区域涉及利用预借鉴模型来执行对象检测，对象分割和/或对象姿势估计。但是，由于以下原因，在实践中不可行：1）预用模型的训练数据集的对象类别可能不会涵盖一般计算机视觉任务的所有对象类别，2）佩戴型模型训练数据集之间的域间隙并且目标任务的数据集可能会影响性能，3）预磨模模型中存在的偏差和方差可能泄漏到导致无意中偏置的目标模型的目标任务中。为了克服这些缺点，我们建议利用一系列视频帧捕获一组公共对象和它们之间的相互作用的公共基本原理，因此视频帧特征之间的共分割的概念可以用自动的能力装配模型专注于突出区域，以最终的方式提高潜在的任务的性能。在这方面，我们提出了一种称为“共分割激活模块”（COSAM）的通用模块，其可以被插入任何CNN，以促进基于CNN的任何CNN的概念在一系列视频帧特征中的关注。我们在三个基于视频的任务中展示Cosam的应用即1）基于视频的人Re-ID，2）视频字幕分类，并证明COSAM能够在视频帧中捕获突出区域，从而引导对于显着的性能改进以及可解释的关注图。

自动视觉解对我们多样化和开放的世界需要计算机视觉模型，以概括为特定任务的最小定制，类似于人类视力。计算机视觉基础型号培训，培训多样化，大型数据集，可以适应各种下游任务，对该任务来解决现实世界计算机视觉应用而言至关重要。虽然现有的视觉基础模型如剪辑，对齐和吴道2.0主要集中在映射图像和文本表示到跨模型共享表示，我们介绍了一台新的计算机视觉基础模型，佛罗伦萨，扩大粗糙的表示（现场）到精细（对象），从静态（图像）到动态（视频），以及从RGB到多个模态（标题，深度）。通过从Web级图像文本数据中纳入通用视觉语言表示，我们的佛罗伦萨模型可以很容易地适应各种计算机视觉任务，例如分类，检索，对象检测，VQA，图像标题，视频检索和动作识别。此外，佛罗伦萨在许多类型的转移学习中表现出出色的表现：全面采样的微调，线性探测，几次射击传输和用于新颖图像和物体的零拍摄传输。所有这些属性对于我们的视觉基础模型至关重要，以提供通用视觉任务。佛罗伦萨实现了新的最先进的导致44个代表性基准，例如Imagenet-1K零射击分类，最高1精度为83.74，最高5个精度为97.18，62.4地图上的Coco微调， 80.36在VQA上，动力学-600上的87.8。

在亲自重新识别（REID）中，最近的研究已经验证了未标记的人图像上的模型的预训练要比ImageNet上要好得多。但是，这些研究直接应用了为图像分类设计的现有自我监督学习（SSL）方法，用于REID，而无需在框架中进行任何适应。这些SSL方法将本地视图的输出（例如红色T恤，蓝色短裤）与同时的全球视图相匹配，从而丢失了很多细节。在本文中，我们提出了一种特定于REID的预训练方法，部分意识的自我监督预训练（PASS），该方法可以生成零件级别的功能以提供细粒度的信息，并且更适合REID。通行证将图像分为几个局部区域，每个区域随机裁剪的本地视图都有特定的可学习[部分]令牌。另一方面，所有地方区域的[部分]也附加到全球视图中。通行证学习以匹配同一[部分]上本地视图的输出和全局视图。也就是说，从本地区域获得的本地视图的[部分]仅与从全球视图中学到的相应[部分]相匹配。结果，每个[部分]可以专注于图像的特定局部区域，并提取该区域的细粒度信息。实验显示通行证在Market1501和MSMT17上的新最先进的表演以及各种REID任务（例如Vanilla vit-s/16）通过Pass Achieves 92.2 \％/90.2 \％/88.5 \％地图准确性，例如Vanilla vit-s/16在Market1501上进行监督/UDA/USL REID。我们的代码可在https://github.com/casia-iva-lab/pass-reid上找到。

In recent years, the Transformer architecture has shown its superiority in the video-based person re-identification task. Inspired by video representation learning, these methods mainly focus on designing modules to extract informative spatial and temporal features. However, they are still limited in extracting local attributes and global identity information, which are critical for the person re-identification task. In this paper, we propose a novel Multi-Stage Spatial-Temporal Aggregation Transformer (MSTAT) with two novel designed proxy embedding modules to address the above issue. Specifically, MSTAT consists of three stages to encode the attribute-associated, the identity-associated, and the attribute-identity-associated information from the video clips, respectively, achieving the holistic perception of the input person. We combine the outputs of all the stages for the final identification. In practice, to save the computational cost, the Spatial-Temporal Aggregation (STA) modules are first adopted in each stage to conduct the self-attention operations along the spatial and temporal dimensions separately. We further introduce the Attribute-Aware and Identity-Aware Proxy embedding modules (AAP and IAP) to extract the informative and discriminative feature representations at different stages. All of them are realized by employing newly designed self-attention operations with specific meanings. Moreover, temporal patch shuffling is also introduced to further improve the robustness of the model. Extensive experimental results demonstrate the effectiveness of the proposed modules in extracting the informative and discriminative information from the videos, and illustrate the MSTAT can achieve state-of-the-art accuracies on various standard benchmarks.

基于文本的人检索旨在根据文本描述找到查询人员。关键是学习视觉文本模式之间的常见潜在空间映射。为了实现这一目标，现有的作品采用细分来获得明确的跨模式对齐方式或利用注意力来探索显着对准。这些方法有两个缺点：1）标记交叉模式比对很耗时。 2）注意方法可以探索显着的跨模式对齐，但可能会忽略一些微妙而有价值的对。为了缓解这些问题，我们为基于文本的人检索引入了一个隐式视觉文本（IVT）框架。与以前的模型不同，IVT利用单个网络来学习两种模式的表示形式，这有助于视觉文本相互作用。为了探索细粒的对准，我们进一步提出了两个隐式语义比对范式：多级比对（MLA）和双向掩码建模（BMM）。 MLA模块在句子，短语和单词级别上探索了更精细的匹配，而BMM模块旨在挖掘视觉和文本模态之间的\ textbf {更多}语义对齐。进行了广泛的实验，以评估公共数据集中提出的IVT，即Cuhk-Pedes，RSTPREID和ICFG-PEDES。即使没有明确的身体部位对准，我们的方法仍然可以达到最先进的表现。代码可在以下网址获得：https：//github.com/tencentyouturesearch/personretrieval-ivt。

视觉问题应答（VQA）任务利用视觉图像和语言分析来回回答图像的文本问题。它是一个流行的研究课题，在过去十年中越来越多的现实应用。本文介绍了我们最近对AliceMind-MMU的研究（阿里巴巴的编码器 - 解码器来自Damo Academy - 多媒体理解的机器智能实验室），其比人类在VQA上获得相似甚至略微更好的结果。这是通过系统地改善VQA流水线来实现的，包括：（1）具有全面的视觉和文本特征表示的预培训; （2）与学习参加的有效跨模型互动; （3）一个新颖的知识挖掘框架，具有专门的专业专家模块，适用于复杂的VQA任务。处理不同类型的视觉问题，需要具有相应的专业知识在提高我们的VQA架构的表现方面发挥着重要作用，这取决于人力水平。进行了广泛的实验和分析，以证明新的研究工作的有效性。

由于其在智能城市和城市监测中的潜在应用，车辆重新ID最近引起了热烈的关注。然而，它遭受了通过观察变化和照明变化引起的大型阶级变化，以及阶级相似性，特别是对于具有类似外观的不同标识。为了处理这些问题，在本文中，我们提出了一种新颖的深度网络架构，其由有意义的属性引导，包括相机视图，车辆类型和用于车辆RE-ID的颜色。特别是，我们的网络是端到端训练的，并包含由相应属性嵌入的深度特征的三个子网（即，相机视图，车辆类型和车辆颜色）。此外，为了克服不同视图的有限载体图像的缺点，我们设计了一个视图指定的生成的对抗性网络来生成多视图车辆图像。对于网络培训，我们在Veri-776数据集上注释了视图标签。请注意，只能使用ID信息直接在其他数据集上直接在其他数据集上采用预先训练的视图（以及类型和颜色）子网，这展示了我们模型的泛化。基准数据集Veri-776和车辆的广泛实验表明，拟议的方法实现了有希望的性能，并对车辆重新ID的新型最先进的性能。

Pre-trained vision-language models like CLIP have recently shown superior performances on various downstream tasks, including image classification and segmentation. However, in fine-grained image re-identification (ReID), the labels are indexes, lacking concrete text descriptions. Therefore, it remains to be determined how such models could be applied to these tasks. This paper first finds out that simply fine-tuning the visual model initialized by the image encoder in CLIP, has already obtained competitive performances in various ReID tasks. Then we propose a two-stage strategy to facilitate a better visual representation. The key idea is to fully exploit the cross-modal description ability in CLIP through a set of learnable text tokens for each ID and give them to the text encoder to form ambiguous descriptions. In the first training stage, image and text encoders from CLIP keep fixed, and only the text tokens are optimized from scratch by the contrastive loss computed within a batch. In the second stage, the ID-specific text tokens and their encoder become static, providing constraints for fine-tuning the image encoder. With the help of the designed loss in the downstream task, the image encoder is able to represent data as vectors in the feature embedding accurately. The effectiveness of the proposed strategy is validated on several datasets for the person or vehicle ReID tasks. Code is available at https://github.com/Syliz517/CLIP-ReID.