从大型预训练模型转移学习对于许多计算机视觉任务来说都是至关重要的。最近的研究表明，由于存在存在的多个对象类的图像被分配单个标签，所以类似于想象成的数据集弱标记。这种模糊的偏置模型朝向单一预测，这可能导致抑制数据中倾向于共同发生的类。灵感来自语言出现文学，我们提出了多标签迭代学习（英里）来利用迭代学习框架从单个标签中融入多标签学习的归纳偏见。英里是一种简单而有效的过程，通过通过与学习瓶颈的连续几代教师和学生网络传播二进制预测来构建图像的多标签描述。实验表明，我们的方法对Imagenet的准确性以及真正的F1分数表现出系统的益处，这表明英里与标签歧义更好地优于标准训练程序，即使在自我监督权重的微调时也会比标准训练程序更好。我们还表明英里有效地减少标签噪音，实现了最先进的性能，如WebVision等现实大规模嘈杂的数据。此外，英里提高了类增量设置中的性能，例如IIRC，它是强大的分发班次。代码：https://github.com/rajeswar18/mile.

Despite significant advances, the performance of state-of-the-art continual learning approaches hinges on the unrealistic scenario of fully labeled data. In this paper, we tackle this challenge and propose an approach for continual semi-supervised learning -- a setting where not all the data samples are labeled. An underlying issue in this scenario is the model forgetting representations of unlabeled data and overfitting the labeled ones. We leverage the power of nearest-neighbor classifiers to non-linearly partition the feature space and learn a strong representation for the current task, as well as distill relevant information from previous tasks. We perform a thorough experimental evaluation and show that our method outperforms all the existing approaches by large margins, setting a strong state of the art on the continual semi-supervised learning paradigm. For example, on CIFAR100 we surpass several others even when using at least 30 times less supervision (0.8% vs. 25% of annotations).

We present Noisy Student Training, a semi-supervised learning approach that works well even when labeled data is abundant. Noisy Student Training achieves 88.4% top-1 accuracy on ImageNet, which is 2.0% better than the state-of-the-art model that requires 3.5B weakly labeled Instagram images. On robustness test sets, it improves ImageNet-A top-1 accuracy from 61.0% to 83.7%, reduces ImageNet-C mean corruption error from 45.7 to 28.3, and reduces ImageNet-P mean flip rate from 27.8 to 12.2.Noisy Student Training extends the idea of self-training and distillation with the use of equal-or-larger student models and noise added to the student during learning. On Im-ageNet, we first train an EfficientNet model on labeled images and use it as a teacher to generate pseudo labels for 300M unlabeled images. We then train a larger Efficient-Net as a student model on the combination of labeled and pseudo labeled images. We iterate this process by putting back the student as the teacher. During the learning of the student, we inject noise such as dropout, stochastic depth, and data augmentation via RandAugment to the student so that the student generalizes better than the teacher. 1 * This work was conducted at Google.

微创手术中的手术工具检测是计算机辅助干预措施的重要组成部分。当前的方法主要是基于有监督的方法，这些方法需要大量的完全标记的数据来培训监督模型，并且由于阶级不平衡问题而患有伪标签偏见。但是，带有边界框注释的大图像数据集通常几乎无法使用。半监督学习（SSL）最近出现了仅使用适度的注释数据训练大型模型的一种手段。除了降低注释成本。 SSL还显示出希望产生更强大和可推广的模型。因此，在本文中，我们在手术工具检测范式中介绍了半监督学习（SSL）框架，该框架旨在通过知识蒸馏方法来减轻培训数据的稀缺和数据失衡。在拟议的工作中，我们培训了一个标有数据的模型，该模型启动了教师学生的联合学习，在该学习中，学生接受了来自未标记数据的教师生成的伪标签的培训。我们提出了一个多级距离，在检测器的利益区域头部具有基于保证金的分类损失函数，以有效地将前景类别与背景区域隔离。我们在M2CAI16-Tool-locations数据集上的结果表明，我们的方法在不同的监督数据设置（1％，2％，5％，注释数据的10％）上的优越性，其中我们的模型可实现8％，12％和27的总体改善在最先进的SSL方法和完全监督的基线上，MAP中的％（在1％标记的数据上）。该代码可在https://github.com/mansoor-at/semi-supervise-surgical-tool-det上获得

Jitendra Malik once said, "Supervision is the opium of the AI researcher". Most deep learning techniques heavily rely on extreme amounts of human labels to work effectively. In today's world, the rate of data creation greatly surpasses the rate of data annotation. Full reliance on human annotations is just a temporary means to solve current closed problems in AI. In reality, only a tiny fraction of data is annotated. Annotation Efficient Learning (AEL) is a study of algorithms to train models effectively with fewer annotations. To thrive in AEL environments, we need deep learning techniques that rely less on manual annotations (e.g., image, bounding-box, and per-pixel labels), but learn useful information from unlabeled data. In this thesis, we explore five different techniques for handling AEL.

除了使用硬标签的标准监督学习外，通常在许多监督学习设置中使用辅助损失来改善模型的概括。例如，知识蒸馏增加了第二个教师模仿模型训练的损失，在该培训中，教师可能是一个验证的模型，可以输出比标签更丰富的分布。同样，在标记数据有限的设置中，弱标记信息以标签函数的形式使用。此处引入辅助损失来对抗标签函数，这些功能可能是基于嘈杂的规则的真实标签近似值。我们解决了学习以原则性方式结合这些损失的问题。我们介绍AMAL，该AMAL使用元学习在验证度量上学习实例特定的权重，以实现损失的最佳混合。在许多知识蒸馏和规则降解域中进行的实验表明，Amal在这些领域中对竞争基准的增长可显着。我们通过经验分析我们的方法，并分享有关其提供性能提升的机制的见解。

大多数现有的工作在几次学习中，依赖于Meta-Learning网络在大型基础数据集上，该网络通常是与目标数据集相同的域。我们解决了跨域几秒钟的问题，其中基础和目标域之间存在大移位。与未标记的目标数据的跨域几秒识别问题在很大程度上在文献中毫无根据。启动是使用自我训练解决此问题的第一个方法。但是，它使用固定的老师在标记的基础数据集上返回，以为未标记的目标样本创建软标签。由于基本数据集和未标记的数据集来自不同的域，因此将基本数据集的类域中的目标图像投影，具有固定的预制模型可能是子最优的。我们提出了一种简单的动态蒸馏基方法，以方便来自新颖/基础数据集的未标记图像。我们通过从教师网络中的未标记图像的未标记版本的预测计算并将其与来自学生网络相同的相同图像的强大版本匹配来施加一致性正常化。教师网络的参数被更新为学生网络参数的指数移动平均值。我们表明所提出的网络了解可以轻松适应目标域的表示，即使它尚未在预先预测阶段的目标专用类别训练。我们的车型优于当前最先进的方法，在BSCD-FSL基准中的5次分类，3.6％的3.6％，并在传统的域名几枪学习任务中显示出竞争性能。

半监督学习方法已成为对打击获得大量注释数据的挑战的活跃研究领域。为了提高半监督学习方法表现的目标，我们提出了一种新颖的框架，Hiematch，一种半监督方法，利用分层信息来降低标签成本并表现以及vanilla半监督学习方法。分层信息通常是具有细粒标签的粗标签（例如，啄木鸟）的粗标签（例如，啄木鸟）的现有知识（例如，柔软的啄木鸟或金朝啄木鸟）。但是，尚未探讨使用使用粗类标签来改进半监督技术的监督。在没有细粒度的标签的情况下，Himatch利用标签层次结构，并使用粗级标签作为弱监控信号。此外，Himatch是一种改进任何半熟的学习框架的通用方法，我们使用我们的结果在最近的最先进的技术Mixmatch和Fixmatch上展示了这一点。我们评估了在两个基准数据集，即CiFar-100和Nabirds上的Himatch疗效。与MixMatch相比，HOMACHACT可以在CIFAR-100上减少50％的粒度标签50％的用量，仅在前1个精度的边缘下降0.59％。代码：https://github.com/07agarg/hiermatch.

Distantly-Supervised Named Entity Recognition (DS-NER) effectively alleviates the data scarcity problem in NER by automatically generating training samples. Unfortunately, the distant supervision may induce noisy labels, thus undermining the robustness of the learned models and restricting the practical application. To relieve this problem, recent works adopt self-training teacher-student frameworks to gradually refine the training labels and improve the generalization ability of NER models. However, we argue that the performance of the current self-training frameworks for DS-NER is severely underestimated by their plain designs, including both inadequate student learning and coarse-grained teacher updating. Therefore, in this paper, we make the first attempt to alleviate these issues by proposing: (1) adaptive teacher learning comprised of joint training of two teacher-student networks and considering both consistent and inconsistent predictions between two teachers, thus promoting comprehensive student learning. (2) fine-grained student ensemble that updates each fragment of the teacher model with a temporal moving average of the corresponding fragment of the student, which enhances consistent predictions on each model fragment against noise. To verify the effectiveness of our proposed method, we conduct experiments on four DS-NER datasets. The experimental results demonstrate that our method significantly surpasses previous SOTA methods.

Deep learning has emerged as an effective solution for solving the task of object detection in images but at the cost of requiring large labeled datasets. To mitigate this cost, semi-supervised object detection methods, which consist in leveraging abundant unlabeled data, have been proposed and have already shown impressive results. However, most of these methods require linking a pseudo-label to a ground-truth object by thresholding. In previous works, this threshold value is usually determined empirically, which is time consuming, and only done for a single data distribution. When the domain, and thus the data distribution, changes, a new and costly parameter search is necessary. In this work, we introduce our method Adaptive Self-Training for Object Detection (ASTOD), which is a simple yet effective teacher-student method. ASTOD determines without cost a threshold value based directly on the ground value of the score histogram. To improve the quality of the teacher predictions, we also propose a novel pseudo-labeling procedure. We use different views of the unlabeled images during the pseudo-labeling step to reduce the number of missed predictions and thus obtain better candidate labels. Our teacher and our student are trained separately, and our method can be used in an iterative fashion by replacing the teacher by the student. On the MS-COCO dataset, our method consistently performs favorably against state-of-the-art methods that do not require a threshold parameter, and shows competitive results with methods that require a parameter sweep search. Additional experiments with respect to a supervised baseline on the DIOR dataset containing satellite images lead to similar conclusions, and prove that it is possible to adapt the score threshold automatically in self-training, regardless of the data distribution.

One paradigm for learning from few labeled examples while making best use of a large amount of unlabeled data is unsupervised pretraining followed by supervised fine-tuning. Although this paradigm uses unlabeled data in a task-agnostic way, in contrast to common approaches to semi-supervised learning for computer vision, we show that it is surprisingly effective for semi-supervised learning on ImageNet. A key ingredient of our approach is the use of big (deep and wide) networks during pretraining and fine-tuning. We find that, the fewer the labels, the more this approach (task-agnostic use of unlabeled data) benefits from a bigger network. After fine-tuning, the big network can be further improved and distilled into a much smaller one with little loss in classification accuracy by using the unlabeled examples for a second time, but in a task-specific way. The proposed semi-supervised learning algorithm can be summarized in three steps: unsupervised pretraining of a big ResNet model using SimCLRv2, supervised fine-tuning on a few labeled examples, and distillation with unlabeled examples for refining and transferring the task-specific knowledge. This procedure achieves 73.9% ImageNet top-1 accuracy with just 1% of the labels (≤13 labeled images per class) using ResNet-50, a 10× improvement in label efficiency over the previous state-of-theart. With 10% of labels, ResNet-50 trained with our method achieves 77.5% top-1 accuracy, outperforming standard supervised training with all of the labels. 1

我们研究了视觉变压器的培训，用于半监督图像分类。变形金刚最近在众多监督的学习任务中表现出令人印象深刻的表现。令人惊讶的是，我们发现视觉变形金刚在半监督的想象中心设置上表现不佳。相比之下，卷积神经网络（CNNS）实现了小标记数据制度的卓越结果。进一步调查揭示了原因是CNN具有强大的空间归纳偏差。灵感来自这一观察，我们介绍了一个联合半监督学习框架，半统一，其中包含变压器分支，卷积分支和精心设计的融合模块，用于分支之间的知识共享。卷积分支在有限监督数据上培训，并生成伪标签，以监督变压器分支对未标记数据的培训。关于Imagenet的广泛实验表明，半统一达到75.5 \％的前1个精度，优于最先进的。此外，我们显示Semifirmer是一般框架，与大多数现代变压器和卷积神经结构兼容。

高质量数据对于现代机器学习是必需的。但是，由于人类的嘈杂和模棱两可的注释，难以获取此类数据。确定图像标签的这种注释的聚合导致数据质量较低。我们提出了一个以数据为中心的图像分类基准，该基准具有9个现实世界数据集和每个图像的多次注释，以调查和量化此类数据质量问题的影响。我们通过询问如何提高数据质量来关注以数据为中心的观点。在数千个实验中，我们表明多个注释可以更好地近似实际的基础类别分布。我们确定硬标签无法捕获数据的歧义，这可能会导致过度自信模型的常见问题。根据呈现的数据集，基准基准和分析，我们为未来创造了多个研究机会。

Lifelong learners must recognize concept vocabularies that evolve over time. A common yet underexplored scenario is learning with class labels over time that refine/expand old classes. For example, humans learn to recognize ${\tt dog}$ before dog breeds. In practical settings, dataset $\textit{versioning}$ often introduces refinement to ontologies, such as autonomous vehicle benchmarks that refine a previous ${\tt vehicle}$ class into ${\tt school-bus}$ as autonomous operations expand to new cities. This paper formalizes a protocol for studying the problem of $\textit{Learning with Evolving Class Ontology}$ (LECO). LECO requires learning classifiers in distinct time periods (TPs); each TP introduces a new ontology of "fine" labels that refines old ontologies of "coarse" labels (e.g., dog breeds that refine the previous ${\tt dog}$). LECO explores such questions as whether to annotate new data or relabel the old, how to leverage coarse labels, and whether to finetune the previous TP's model or train from scratch. To answer these questions, we leverage insights from related problems such as class-incremental learning. We validate them under the LECO protocol through the lens of image classification (CIFAR and iNaturalist) and semantic segmentation (Mapillary). Our experiments lead to surprising conclusions; while the current status quo is to relabel existing datasets with new ontologies (such as COCO-to-LVIS or Mapillary1.2-to-2.0), LECO demonstrates that a far better strategy is to annotate $\textit{new}$ data with the new ontology. However, this produces an aggregate dataset with inconsistent old-vs-new labels, complicating learning. To address this challenge, we adopt methods from semi-supervised and partial-label learning. Such strategies can surprisingly be made near-optimal, approaching an "oracle" that learns on the aggregate dataset exhaustively labeled with the newest ontology.

糖尿病性视网膜病变（DR）是发达国家工人衰老人群中失明的主要原因之一，这是由于糖尿病的副作用降低了视网膜的血液供应。深度神经网络已被广泛用于自动化系统中，以在眼底图像上进行DR分类。但是，这些模型需要大量带注释的图像。在医疗领域，专家的注释昂贵，乏味且耗时。结果，提供了有限数量的注释图像。本文提出了一种半监督的方法，该方法利用未标记的图像和标记的图像来训练一种检测糖尿病性视网膜病的模型。提出的方法通过自我监督的学习使用无监督的预告片，然后使用一小部分标记的图像和知识蒸馏来监督微调，以提高分类任务的性能。在Eyepacs测试和Messidor-2数据集中评估了此方法，仅使用2％的Eyepacs列车标记图像，分别使用0.94和0.89 AUC。

We demonstrate that self-learning techniques like entropy minimization and pseudo-labeling are simple and effective at improving performance of a deployed computer vision model under systematic domain shifts. We conduct a wide range of large-scale experiments and show consistent improvements irrespective of the model architecture, the pre-training technique or the type of distribution shift. At the same time, self-learning is simple to use in practice because it does not require knowledge or access to the original training data or scheme, is robust to hyperparameter choices, is straight-forward to implement and requires only a few adaptation epochs. This makes self-learning techniques highly attractive for any practitioner who applies machine learning algorithms in the real world. We present state-of-the-art adaptation results on CIFAR10-C (8.5% error), ImageNet-C (22.0% mCE), ImageNet-R (17.4% error) and ImageNet-A (14.8% error), theoretically study the dynamics of self-supervised adaptation methods and propose a new classification dataset (ImageNet-D) which is challenging even with adaptation.

我们提出了将粗大分类标签纳入细粒域中的图像分类器的技术。这种标签通常可以通过较小的努力来获得较小的粒状域，例如根据生物分类法组织类别的自然界。在三个王国组成的半inat数据集上，包括Phylum标签，在使用ImageNet预训练模型的转移学习设置中将物种级别分类精度提高了6％。使用称为FixMatch的最先进的半监督学习算法的分层标签结构提高了1.3％的性能。当提供诸如类或订单的详细标签或从头开始培训时，相对收益更大。但是，我们发现大多数方法对来自新类别的域名数据的存在并不强大。我们提出了一种技术来从层次结构引导的大量未标记图像中选择相关数据，这提高了鲁棒性。总体而言，我们的实验表明，具有粗大分类标签的半监督学习对于细粒度域中的培训分类器是实用的。

This work tackles the problem of semi-supervised learning of image classifiers. Our main insight is that the field of semi-supervised learning can benefit from the quickly advancing field of self-supervised visual representation learning. Unifying these two approaches, we propose the framework of self-supervised semi-supervised learning (S 4 L) and use it to derive two novel semi-supervised image classification methods. We demonstrate the effectiveness of these methods in comparison to both carefully tuned baselines, and existing semi-supervised learning methods. We then show that S 4 L and existing semi-supervised methods can be jointly trained, yielding a new state-of-the-art result on semi-supervised ILSVRC-2012 with 10% of labels.

Positive-Unlabeled (PU) learning aims to learn a model with rare positive samples and abundant unlabeled samples. Compared with classical binary classification, the task of PU learning is much more challenging due to the existence of many incompletely-annotated data instances. Since only part of the most confident positive samples are available and evidence is not enough to categorize the rest samples, many of these unlabeled data may also be the positive samples. Research on this topic is particularly useful and essential to many real-world tasks which demand very expensive labelling cost. For example, the recognition tasks in disease diagnosis, recommendation system and satellite image recognition may only have few positive samples that can be annotated by the experts. These methods mainly omit the intrinsic hardness of some unlabeled data, which can result in sub-optimal performance as a consequence of fitting the easy noisy data and not sufficiently utilizing the hard data. In this paper, we focus on improving the commonly-used nnPU with a novel training pipeline. We highlight the intrinsic difference of hardness of samples in the dataset and the proper learning strategies for easy and hard data. By considering this fact, we propose first splitting the unlabeled dataset with an early-stop strategy. The samples that have inconsistent predictions between the temporary and base model are considered as hard samples. Then the model utilizes a noise-tolerant Jensen-Shannon divergence loss for easy data; and a dual-source consistency regularization for hard data which includes a cross-consistency between student and base model for low-level features and self-consistency for high-level features and predictions, respectively.