Deep metric learning aims to learn an embedding space, where semantically similar samples are close together and dissimilar ones are repelled against. To explore more hard and informative training signals for augmentation and generalization, recent methods focus on generating synthetic samples to boost metric learning losses. However, these methods just use the deterministic and class-independent generations (e.g., simple linear interpolation), which only can cover the limited part of distribution spaces around original samples. They have overlooked the wide characteristic changes of different classes and can not model abundant intra-class variations for generations. Therefore, generated samples not only lack rich semantics within the certain class, but also might be noisy signals to disturb training. In this paper, we propose a novel intra-class adaptive augmentation (IAA) framework for deep metric learning. We reasonably estimate intra-class variations for every class and generate adaptive synthetic samples to support hard samples mining and boost metric learning losses. Further, for most datasets that have a few samples within the class, we propose the neighbor correction to revise the inaccurate estimations, according to our correlation discovery where similar classes generally have similar variation distributions. Extensive experiments on five benchmarks show our method significantly improves and outperforms the state-of-the-art methods on retrieval performances by 3%-6%. Our code is available at https://github.com/darkpromise98/IAA

深度度量学习（DML）有助于学习嵌入功能，以将语义上的数据投射到附近的嵌入空间中，并在许多应用中起着至关重要的作用，例如图像检索和面部识别。但是，DML方法的性能通常很大程度上取决于采样方法，从训练中的嵌入空间中选择有效的数据。实际上，嵌入空间中的嵌入是通过一些深层模型获得的，其中嵌入空间通常由于缺乏训练点而在贫瘠的区域中，导致所谓的“缺失嵌入”问题。此问题可能会损害样品质量，从而导致DML性能退化。在这项工作中，我们研究了如何减轻“缺失”问题以提高采样质量并实现有效的DML。为此，我们提出了一个密集锚定的采样（DAS）方案，该方案将嵌入的数据点视为“锚”，并利用锚附近的嵌入空间来密集地生成无数据点的嵌入。具体而言，我们建议用判别性特征缩放（DFS）和多个锚点利用单个锚周围的嵌入空间，并具有记忆转换转换（MTS）。通过这种方式，通过有或没有数据点的嵌入方式，我们能够提供更多的嵌入以促进采样过程，从而提高DML的性能。我们的方法毫不费力地集成到现有的DML框架中，并在没有铃铛和哨声的情况下改进了它们。在三个基准数据集上进行的广泛实验证明了我们方法的优势。

Recent methods for deep metric learning have been focusing on designing different contrastive loss functions between positive and negative pairs of samples so that the learned feature embedding is able to pull positive samples of the same class closer and push negative samples from different classes away from each other. In this work, we recognize that there is a significant semantic gap between features at the intermediate feature layer and class labels at the final output layer. To bridge this gap, we develop a contrastive Bayesian analysis to characterize and model the posterior probabilities of image labels conditioned by their features similarity in a contrastive learning setting. This contrastive Bayesian analysis leads to a new loss function for deep metric learning. To improve the generalization capability of the proposed method onto new classes, we further extend the contrastive Bayesian loss with a metric variance constraint. Our experimental results and ablation studies demonstrate that the proposed contrastive Bayesian metric learning method significantly improves the performance of deep metric learning in both supervised and pseudo-supervised scenarios, outperforming existing methods by a large margin.

A family of loss functions built on pair-based computation have been proposed in the literature which provide a myriad of solutions for deep metric learning. In this paper, we provide a general weighting framework for understanding recent pair-based loss functions. Our contributions are three-fold: (1) we establish a General Pair Weighting (GPW) framework, which casts the sampling problem of deep metric learning into a unified view of pair weighting through gradient analysis, providing a powerful tool for understanding recent pair-based loss functions; (2) we show that with GPW, various existing pair-based methods can be compared and discussed comprehensively, with clear differences and key limitations identified; (3) we propose a new loss called multi-similarity loss (MS loss) under the GPW, which is implemented in two iterative steps (i.e., mining and weighting). This allows it to fully consider three similarities for pair weighting, providing a more principled approach for collecting and weighting informative pairs. Finally, the proposed MS loss obtains new state-of-the-art performance on four image retrieval benchmarks, where it outperforms the most recent approaches, such as ABE [14] and HTL [4], by a large margin, e.g., , and 80.9% → 88.0% on In-Shop Clothes Retrieval dataset

大多数深度度量学习（DML）方法采用了一种策略，该策略迫使所有积极样本在嵌入空间中靠近，同时使它们远离负面样本。但是，这种策略忽略了正（负）样本的内部关系，并且通常导致过度拟合，尤其是在存在硬样品和标签错误的情况下。在这项工作中，我们提出了一个简单而有效的正则化，即列表自我验证（LSD），该化逐渐提炼模型的知识，以适应批处理中每个样本对的更合适的距离目标。LSD鼓励在正（负）样本中更平稳的嵌入和信息挖掘，以减轻过度拟合并从而改善概括。我们的LSD可以直接集成到一般的DML框架中。广泛的实验表明，LSD始终提高多个数据集上各种度量学习方法的性能。

深度度量学习（DML）模型通常需要强大的本地和全球表示，但是，DML模型培训中的本地和全球特征的有效整合是一项挑战。 DML模型通常具有特定损耗功能，包括基于成对和基于代理的损失。基于成对的损耗函数利用数据点之间丰富的语义关系，然而，在DML模型训练期间经常遭受缓慢的收敛。另一方面，基于代理的损耗功能通常会导致培训期间收敛的显着加速，而基于代理的损失通常不会完全探索数据点之间的丰富关系。在本文中，我们提出了一种新的DML方法来解决这些挑战。所提出的DML方法通过集成对基于基于代理的损耗函数来利用丰富的数据到数据关系以及快速收敛来利用混合丢失来利用混合丢失。此外，所提出的DML方法利用全局和本地功能在DML模型培训中获得丰富的表示。最后，我们还使用二阶注意功能增强，以提高准确和有效的检索。在我们的实验中，我们在四个公共基准中广泛评估了所提出的DML方法，实验结果表明，该方法在所有基准上实现了最先进的性能。

深度度量学习（DML）旨在最大程度地减少嵌入图像中成对内部/间阶层接近性违规的经验预期损失。我们将DML与有限机会限制的可行性问题联系起来。我们表明，基于代理的DML的最小化器满足了某些机会限制，并且基于代理方法的最坏情况可以通过围绕类代理的最小球的半径来表征，以覆盖相应类的整个域样本，建议每课多个代理有助于表现。为了提供可扩展的算法并利用更多代理，我们考虑了基于代理的DML实例的最小化者所隐含的机会限制，并将DML重新制定为在此类约束的交叉点中找到可行的点，从而导致问题近似解决。迭代预测。简而言之，我们反复训练基于代理的损失，并用故意选择的新样本的嵌入来重新定位代理。我们将我们的方法应用于公认的损失，并在四个流行的基准数据集上评估图像检索。优于最先进的方法，我们的方法一致地提高了应用损失的性能。代码可在以下网址找到：https：//github.com/yetigurbuz/ccp-dml

在本文中，我们提出了一种强大的样本生成方案来构建信息性三联网。所提出的硬样品生成是一种两级合成框架，通过两个阶段的有效正和负样品发生器产生硬样品。第一阶段将锚定向对具有分段线性操作，通过巧妙地设计条件生成的对抗网络来提高产生的样本的质量，以降低模式崩溃的风险。第二阶段利用自适应反向度量约束来生成最终的硬样本。在几个基准数据集上进行广泛的实验，验证了我们的方法比现有的硬样生成算法达到卓越的性能。此外，我们还发现，我们建议的硬样品生成方法结合现有的三态挖掘策略可以进一步提高深度度量学习性能。

深度指标学习旨在学习嵌入空间，即使在训练期间他们的类是看不见的，数据之间的距离反映了他们的类等价。然而，培训中可用的有限数量排除了学习嵌入空间的概括。由此激励，我们介绍了一种新的数据增强方法，该方法合成了新颖类及其嵌入向量。我们的方法可以向嵌入式模型提供丰富的语义信息，通过在原始数据中使用新类别增强培训数据来提高其泛化。我们通过学习和利用条件生成模型来实现这个想法，其中，给定类标签和噪声，产生类的随机嵌入向量。我们所提出的发电机允许损失通过增强现实和多样的类来使用更丰富的级关系，从而更好地推广了看不见的样本。公共基准数据集上的实验结果表明，我们的方法明确提高了基于代理的损失的性能。

在距离度量学习网络的培训期间，典型损耗函数的最小值可以被认为是满足由训练数据施加的一组约束的“可行点”。为此，我们将距离度量学习问题重构为查找约束集的可行点，其中训练数据的嵌入向量满足所需的类内和帧间接近度。由约束集引起的可行性集被表示为仅针对训练数据的特定样本（来自每个类别的样本）强制执行接近约束的宽松可行集合。然后，通过在那些可行的组上执行交替的投影来大致解决可行点问题。这种方法引入了正则化术语，并导致最小化具有系统批量组结构的典型损失函数，其中这些批次被约束以包含来自每个类的相同样本，用于一定数量的迭代。此外，这些特定样品可以被认为是阶级代表，允许在批量构建期间有效地利用艰难的挖掘。所提出的技术应用于良好的损失，并在斯坦福在线产品，CAR196和CUB200-2011数据集进行了评估，用于图像检索和聚类。表现优于现有技术，所提出的方法一致地提高了综合损失函数的性能，没有额外的计算成本，并通过硬负面挖掘进一步提高性能。

Supervision for metric learning has long been given in the form of equivalence between human-labeled classes. Although this type of supervision has been a basis of metric learning for decades, we argue that it hinders further advances of the field. In this regard, we propose a new regularization method, dubbed HIER, to discover the latent semantic hierarchy of training data, and to deploy the hierarchy to provide richer and more fine-grained supervision than inter-class separability induced by common metric learning losses. HIER achieved this goal with no annotation for the semantic hierarchy but by learning hierarchical proxies in hyperbolic spaces. The hierarchical proxies are learnable parameters, and each of them is trained to serve as an ancestor of a group of data or other proxies to approximate the semantic hierarchy among them. HIER deals with the proxies along with data in hyperbolic space since geometric properties of the space are well-suited to represent their hierarchical structure. The efficacy of HIER was evaluated on four standard benchmarks, where it consistently improved performance of conventional methods when integrated with them, and consequently achieved the best records, surpassing even the existing hyperbolic metric learning technique, in almost all settings.

可以通过对手动预定义目标的监督（例如，一hot或Hadamard代码）进行深入的表示学习来解决细粒度的视觉分类。这种目标编码方案对于模型间相关性的灵活性较小，并且对稀疏和不平衡的数据分布也很敏感。鉴于此，本文介绍了一种新颖的目标编码方案 - 动态目标关系图（DTRG），作为辅助特征正则化，是一个自生成的结构输出，可根据输入图像映射。具体而言，类级特征中心的在线计算旨在在表示空间中生成跨类别距离，因此可以通过非参数方式通过动态图来描绘。明确最大程度地减少锚定在这些级别中心的阶层内特征变化可以鼓励学习判别特征。此外，由于利用了类间的依赖性，提出的目标图可以减轻代表学习中的数据稀疏性和不稳定。受混合风格数据增强的最新成功的启发，本文将随机性引入了动态目标关系图的软结构，以进一步探索目标类别的关系多样性。实验结果可以证明我们方法对多个视觉分类任务的许多不同基准的有效性，尤其是在流行的细粒对象基准上实现最先进的性能以及针对稀疏和不平衡数据的出色鲁棒性。源代码可在https://github.com/akonlau/dtrg上公开提供。

Deep Metric Learning (DML) learns a non-linear semantic embedding from input data that brings similar pairs together while keeping dissimilar data away from each other. To this end, many different methods are proposed in the last decade with promising results in various applications. The success of a DML algorithm greatly depends on its loss function. However, no loss function is perfect, and it deals only with some aspects of an optimal similarity embedding. Besides, the generalizability of the DML on unseen categories during the test stage is an important matter that is not considered by existing loss functions. To address these challenges, we propose novel approaches to combine different losses built on top of a shared deep feature extractor. The proposed ensemble of losses enforces the deep model to extract features that are consistent with all losses. Since the selected losses are diverse and each emphasizes different aspects of an optimal semantic embedding, our effective combining methods yield a considerable improvement over any individual loss and generalize well on unseen categories. Here, there is no limitation in choosing loss functions, and our methods can work with any set of existing ones. Besides, they can optimize each loss function as well as its weight in an end-to-end paradigm with no need to adjust any hyper-parameter. We evaluate our methods on some popular datasets from the machine vision domain in conventional Zero-Shot-Learning (ZSL) settings. The results are very encouraging and show that our methods outperform all baseline losses by a large margin in all datasets.

从一个非常少数标记的样品中学习新颖的课程引起了机器学习区域的越来越高。最近关于基于元学习或转移学习的基于范例的研究表明，良好特征空间的获取信息可以是在几次拍摄任务上实现有利性能的有效解决方案。在本文中，我们提出了一种简单但有效的范式，该范式解耦了学习特征表示和分类器的任务，并且只能通过典型的传送学习培训策略从基类嵌入体系结构的特征。为了在每个类别内保持跨基地和新类别和辨别能力的泛化能力，我们提出了一种双路径特征学习方案，其有效地结合了与对比特征结构的结构相似性。以这种方式，内部级别对齐和级别的均匀性可以很好地平衡，并且导致性能提高。三个流行基准测试的实验表明，当与简单的基于原型的分类器结合起来时，我们的方法仍然可以在电感或转换推理设置中的标准和广义的几次射击问题达到有希望的结果。

Learning the distance metric between pairs of examples is of great importance for learning and visual recognition. With the remarkable success from the state of the art convolutional neural networks, recent works [1, 31] have shown promising results on discriminatively training the networks to learn semantic feature embeddings where similar examples are mapped close to each other and dissimilar examples are mapped farther apart. In this paper, we describe an algorithm for taking full advantage of the training batches in the neural network training by lifting the vector of pairwise distances within the batch to the matrix of pairwise distances. This step enables the algorithm to learn the state of the art feature embedding by optimizing a novel structured prediction objective on the lifted problem. Additionally, we collected Online Products dataset: 120k images of 23k classes of online products for metric learning. Our experiments on the CUB-200-2011 [37], CARS196 [19], and Online Products datasets demonstrate significant improvement over existing deep feature embedding methods on all experimented embedding sizes with the GoogLeNet [33] network.

Deep embeddings answer one simple question: How similar are two images? Learning these embeddings is the bedrock of verification, zero-shot learning, and visual search. The most prominent approaches optimize a deep convolutional network with a suitable loss function, such as contrastive loss or triplet loss. While a rich line of work focuses solely on the loss functions, we show in this paper that selecting training examples plays an equally important role. We propose distance weighted sampling, which selects more informative and stable examples than traditional approaches. In addition, we show that a simple margin based loss is sufficient to outperform all other loss functions. We evaluate our approach on the Stanford Online Products, CAR196, and the CUB200-2011 datasets for image retrieval and clustering, and on the LFW dataset for face verification. Our method achieves state-of-the-art performance on all of them.

嘈杂的标签通常在现实世界数据中找到，这导致深神经网络的性能下降。手动清洁数据是劳动密集型和耗时的。以前的研究主要侧重于加强对嘈杂标签的分类模型，而对嘈杂标签的深度度量学习（DML）的鲁棒性仍然较少。在本文中，通过提出与DML的内存（棱镜）方法提出基于概率排名的实例选择来弥合这一重要差异。棱镜计算清洁标签的概率，并滤除潜在的噪声样本。具体地，我们提出了一种新方法，即Von Mises-Fisher分配相似性（VMF-SIM），通过估计每个数据类的VON MISES-FISHER（VMF）分布来计算这种概率。与现有的平均相似性方法（AVGSIM）相比，除了平均相似度之外，VMF-SIM还考虑每个类的方差。通过这种设计，所提出的方法可以应对挑战的DML情况，其中大多数样本是嘈杂的。在合成和现实世界嘈杂的数据集中的广泛实验表明，拟议的方法在合理的培训时间内实现了高达@ 1的精度高达8.37％的精度@ 1。

最近，深度度量学习（DML）的实质性研究努力集中在设计复杂的成对距离损失，这需要卷积方案来缓解优化，例如样本挖掘或配对加权。分类的标准交叉熵损失在DML中大大忽略了。在表面上，交叉熵可能看起来不相关，与度量学习无关，因为它没有明确地涉及成对距离。但是，我们提供了一个理论分析，将交叉熵链接到几个众所周知的和最近的成对损耗。我们的连接是从两种不同的观点绘制：一个基于明确的优化洞察力;另一个关于标签与学到的相互信息的判别和生成观点。首先，我们明确证明交叉熵是新的成对损耗的上限，其具有类似于各种成对损耗的结构：它最大限度地减少了课堂内距离，同时最大化了阶级间距离。结果，最小化交叉熵可以被视为近似束缚 - 优化（或大大最小化）算法，以最小化该成对丢失。其次，我们表明，更一般地，最小化跨熵实际上是相当于最大化互联信息的相同信息，我们连接多个众所周知的成对损耗。此外，我们表明，各种标准成对损耗可以通过绑定的关系彼此明确地与彼此有关。我们的研究结果表明，交叉熵代表了最大化相互信息的代理 - 作为成对损耗，没有必要进行复杂的样品挖掘启发式。我们对四个标准DML基准测试的实验强烈支持我们的调查结果。我们获得最先进的结果，优于最近和复杂的DML方法。

Recent years witnessed the breakthrough of face recognition with deep convolutional neural networks. Dozens of papers in the field of FR are published every year. Some of them were applied in the industrial community and played an important role in human life such as device unlock, mobile payment, and so on. This paper provides an introduction to face recognition, including its history, pipeline, algorithms based on conventional manually designed features or deep learning, mainstream training, evaluation datasets, and related applications. We have analyzed and compared state-of-the-art works as many as possible, and also carefully designed a set of experiments to find the effect of backbone size and data distribution. This survey is a material of the tutorial named The Practical Face Recognition Technology in the Industrial World in the FG2023.

Recently, a popular line of research in face recognition is adopting margins in the well-established softmax loss function to maximize class separability. In this paper, we first introduce an Additive Angular Margin Loss (ArcFace), which not only has a clear geometric interpretation but also significantly enhances the discriminative power. Since ArcFace is susceptible to the massive label noise, we further propose sub-center ArcFace, in which each class contains K sub-centers and training samples only need to be close to any of the K positive sub-centers. Sub-center ArcFace encourages one dominant sub-class that contains the majority of clean faces and non-dominant sub-classes that include hard or noisy faces. Based on this self-propelled isolation, we boost the performance through automatically purifying raw web faces under massive real-world noise. Besides discriminative feature embedding, we also explore the inverse problem, mapping feature vectors to face images. Without training any additional generator or discriminator, the pre-trained ArcFace model can generate identity-preserved face images for both subjects inside and outside the training data only by using the network gradient and Batch Normalization (BN) priors. Extensive experiments demonstrate that ArcFace can enhance the discriminative feature embedding as well as strengthen the generative face synthesis.