We present a novel clustering objective that learns a neural network classifier from scratch, given only unlabelled data samples. The model discovers clusters that accurately match semantic classes, achieving state-of-the-art results in eight unsupervised clustering benchmarks spanning image classification and segmentation. These include STL10, an unsupervised variant of ImageNet, and CIFAR10, where we significantly beat the accuracy of our closest competitors by 6.6 and 9.5 absolute percentage points respectively. The method is not specialised to computer vision and operates on any paired dataset samples; in our experiments we use random transforms to obtain a pair from each image. The trained network directly outputs semantic labels, rather than high dimensional representations that need external processing to be usable for semantic clustering. The objective is simply to maximise mutual information between the class assignments of each pair. It is easy to implement and rigorously grounded in information theory, meaning we effortlessly avoid degenerate solutions that other clustering methods are susceptible to. In addition to the fully unsupervised mode, we also test two semi-supervised settings. The first achieves 88.8% accuracy on STL10 classification, setting a new global state-of-the-art over all existing methods (whether supervised, semi-supervised or unsupervised). The second shows robustness to 90% reductions in label coverage, of relevance to applications that wish to make use of small amounts of labels. github.com/xu-ji/IIC

Can we automatically group images into semantically meaningful clusters when ground-truth annotations are absent? The task of unsupervised image classification remains an important, and open challenge in computer vision. Several recent approaches have tried to tackle this problem in an end-to-end fashion. In this paper, we deviate from recent works, and advocate a two-step approach where feature learning and clustering are decoupled. First, a self-supervised task from representation learning is employed to obtain semantically meaningful features. Second, we use the obtained features as a prior in a learnable clustering approach. In doing so, we remove the ability for cluster learning to depend on low-level features, which is present in current end-to-end learning approaches. Experimental evaluation shows that we outperform state-of-the-art methods by large margins, in particular +26.6% on CI-FAR10, +25.0% on CIFAR100-20 and +21.3% on STL10 in terms of classification accuracy. Furthermore, our method is the first to perform well on a large-scale dataset for image classification. In particular, we obtain promising results on ImageNet, and outperform several semi-supervised learning methods in the low-data regime without the use of any groundtruth annotations. The code is made publicly available here.

Combining clustering and representation learning is one of the most promising approaches for unsupervised learning of deep neural networks. However, doing so naively leads to ill posed learning problems with degenerate solutions. In this paper, we propose a novel and principled learning formulation that addresses these issues. The method is obtained by maximizing the information between labels and input data indices. We show that this criterion extends standard crossentropy minimization to an optimal transport problem, which we solve efficiently for millions of input images and thousands of labels using a fast variant of the Sinkhorn-Knopp algorithm. The resulting method is able to self-label visual data so as to train highly competitive image representations without manual labels. Our method achieves state of the art representation learning performance for AlexNet and ResNet-50 on SVHN, CIFAR-10, CIFAR-100 and ImageNet and yields the first self-supervised AlexNet that outperforms the supervised Pascal VOC detection baseline. Code and models are available 1 .

自我监督的学习（SSL）已成为无需人类注释而产生不变表示的流行方法。但是，通过在输入数据上利用先前的在线转换功能来实现所需的不变表示。结果，每个SSL框架都是针对特定数据类型（例如，视觉数据）定制的，如果将其用于其他数据集类型，则需要进行进一步的修改。另一方面，是一个通用且广泛适用的框架的自动编码器（AE），主要集中于缩小尺寸，不适合学习不变表示。本文提出了一个基于阻止退化解决方案的受限自我标签分配过程的通用SSL框架。具体而言，先前的转换函数被用无监督的对抗训练的训练过程得出，以实现不变表示。通过自我转化机制，可以从相同的输入数据生成成对的增强实例。最后，基于对比度学习的培训目标是通过利用自我标签分配和自我转化机制来设计的。尽管自我转化过程非常通用，但拟议的培训策略的表现优于基于AE结构的大多数最先进的表示方法。为了验证我们的方法的性能，我们对四种类型的数据进行实验，即视觉，音频，文本和质谱数据，并用四个定量指标进行比较。我们的比较结果表明，所提出的方法证明了鲁棒性并成功识别数据集中的模式。

自我监督学习的进步带来了强大的一般图像表示学习方法。到目前为止，它主要集中在图像级学习上。反过来，诸如无监督图像细分之类的任务并没有从这种趋势中受益，因为它们需要空间多样性的表示。但是，学习密集的表示具有挑战性，因为在无监督的环境中，尚不清楚如何指导模型学习与各种潜在对象类别相对应的表示形式。在本文中，我们认为对物体部分的自我监督学习是解决此问题的方法。对象部分是可以推广的：它们是独立于对象定义的先验性，但可以分组以形成对象后验。为此，我们利用最近提出的视觉变压器参与对象的能力，并将其与空间密集的聚类任务相结合，以微调空间令牌。我们的方法超过了三个语义分割基准的最新方法，提高了17％-3％，表明我们的表示在各种对象定义下都是用途广泛的。最后，我们将其扩展到完全无监督的分割 - 即使在测试时间也可以完全避免使用标签信息 - 并证明了一种基于社区检测的自动合并发现的对象零件的简单方法可产生可观的收益。

This work investigates unsupervised learning of representations by maximizing mutual information between an input and the output of a deep neural network encoder. Importantly, we show that structure matters: incorporating knowledge about locality in the input into the objective can significantly improve a representation's suitability for downstream tasks. We further control characteristics of the representation by matching to a prior distribution adversarially. Our method, which we call Deep InfoMax (DIM), outperforms a number of popular unsupervised learning methods and compares favorably with fully-supervised learning on several classification tasks in with some standard architectures. DIM opens new avenues for unsupervised learning of representations and is an important step towards flexible formulations of representation learning objectives for specific end-goals.

在深度学习研究中，自学学习（SSL）引起了极大的关注，引起了计算机视觉和遥感社区的兴趣。尽管计算机视觉取得了很大的成功，但SSL在地球观测领域的大部分潜力仍然锁定。在本文中，我们对在遥感的背景下为计算机视觉的SSL概念和最新发展提供了介绍，并回顾了SSL中的概念和最新发展。此外，我们在流行的遥感数据集上提供了现代SSL算法的初步基准，从而验证了SSL在遥感中的潜力，并提供了有关数据增强的扩展研究。最后，我们确定了SSL未来研究的有希望的方向的地球观察（SSL4EO），以铺平了两个领域的富有成效的相互作用。

由于其最近在减少监督学习的差距方面取得了成功，自我监督的学习方法正在增加计算机愿景的牵引力。在自然语言处理（NLP）中，自我监督的学习和变形金刚已经是选择的方法。最近的文献表明，变压器也在计算机愿景中越来越受欢迎。到目前为止，当使用大规模监督数据或某种共同监督时，视觉变压器已被证明可以很好地工作。在教师网络方面。这些监督的普试视觉变压器在下游任务中实现了非常好的变化，变化最小。在这项工作中，我们调查自我监督学习的预用图像/视觉变压器，然后使用它们进行下游分类任务的优点。我们提出了自我监督的视觉变压器（坐在）并讨论了几种自我监督的培训机制，以获得借口模型。静坐的架构灵活性允许我们将其用作自动统计器，并无缝地使用多个自我监控任务。我们表明，可以在小规模数据集上进行预训练，以便在小型数据集上进行下游分类任务，包括几千个图像而不是数百万的图像。使用公共协议对所提出的方法进行评估标准数据集。结果展示了变压器的强度及其对自我监督学习的适用性。我们通过大边缘表现出现有的自我监督学习方法。我们还观察到坐着很好，很少有镜头学习，并且还表明它通过简单地训练从坐的学到的学习功能的线性分类器来学习有用的表示。预先训练，FineTuning和评估代码将在以下：https://github.com/sara-ahmed/sit。

机器学习模型通常会遇到与训练分布不同的样本。无法识别分布（OOD）样本，因此将该样本分配给课堂标签会显着损害模​​型的可靠性。由于其对在开放世界中的安全部署模型的重要性，该问题引起了重大关注。由于对所有可能的未知分布进行建模的棘手性，检测OOD样品是具有挑战性的。迄今为止，一些研究领域解决了检测陌生样本的问题，包括异常检测，新颖性检测，一级学习，开放式识别识别和分布外检测。尽管有相似和共同的概念，但分别分布，开放式检测和异常检测已被独立研究。因此，这些研究途径尚未交叉授粉，创造了研究障碍。尽管某些调查打算概述这些方法，但它们似乎仅关注特定领域，而无需检查不同领域之间的关系。这项调查旨在在确定其共同点的同时，对各个领域的众多著名作品进行跨域和全面的审查。研究人员可以从不同领域的研究进展概述中受益，并协同发展未来的方法。此外，据我们所知，虽然进行异常检测或单级学习进行了调查，但没有关于分布外检测的全面或最新的调查，我们的调查可广泛涵盖。最后，有了统一的跨域视角，我们讨论并阐明了未来的研究线，打算将这些领域更加紧密地融为一体。

在本文中，我们考虑一个高度通用的图像识别设置，其中，给定标记和未标记的图像集，任务是在未标记的集合中对所有图像进行分类。这里，未标记的图像可以来自标记的类或新颖的图像。现有的识别方法无法处理此设置，因为它们会产生几种限制性假设，例如仅来自已知或未知 - 类的未标记的实例以及已知的未知类的数量。我们解决了更加不受约束的环境，命名为“广义类别发现”，并挑战所有这些假设。我们首先通过从新型类别发现和适应这项任务的最先进的算法来建立强有力的基线。接下来，我们建议使用视觉变形金刚，为此开放的世界设置具有对比的代表学习。然后，我们介绍一个简单而有效的半监督$ k $ -means方法，将未标记的数据自动聚类，看不见的类，显着优于基线。最后，我们还提出了一种新的方法来估计未标记数据中的类别数。我们彻底评估了我们在公共数据集上的方法，包括Cifar10，CiFar100和Imagenet-100，以及包括幼崽，斯坦福汽车和植宝司19，包括幼崽，斯坦福汽车和Herbarium19，在这个新的环境中基准测试，以培养未来的研究。

自我监督的视觉表示学习最近引起了重大的研究兴趣。虽然一种评估自我监督表示的常见方法是通过转移到各种下游任务，但我们研究了衡量其可解释性的问题，即了解原始表示中编码的语义。我们将后者提出为估计表示和手动标记概念空间之间的相互信息。为了量化这一点，我们介绍了一个解码瓶颈：必须通过简单的预测变量捕获信息，将概念映射到表示空间中的簇。我们称之为反向线性探测的方法为表示表示的语义敏感。该措施还能够检测出表示何时包含概念的组合（例如“红色苹果”），而不仅仅是单个属性（独立的“红色”和“苹果”）。最后，我们建议使用监督分类器自动标记大型数据集，以丰富用于探测的概念的空间。我们使用我们的方法来评估大量的自我监督表示形式，通过解释性对它们进行排名，并通过线性探针与标准评估相比出现的差异，并讨论了一些定性的见解。代码为：{\ Scriptsize {\ url {https://github.com/iro-cp/ssl-qrp}}}}}。

Deep convolutional networks have proven to be very successful in learning task specific features that allow for unprecedented performance on various computer vision tasks. Training of such networks follows mostly the supervised learning paradigm, where sufficiently many input-output pairs are required for training. Acquisition of large training sets is one of the key challenges, when approaching a new task. In this paper, we aim for generic feature learning and present an approach for training a convolutional network using only unlabeled data. To this end, we train the network to discriminate between a set of surrogate classes. Each surrogate class is formed by applying a variety of transformations to a randomly sampled 'seed' image patch. In contrast to supervised network training, the resulting feature representation is not class specific. It rather provides robustness to the transformations that have been applied during training. This generic feature representation allows for classification results that outperform the state of the art for unsupervised learning on several popular datasets . While such generic features cannot compete with class specific features from supervised training on a classification task, we show that they are advantageous on geometric matching problems, where they also outperform the SIFT descriptor.

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.

Human observers can learn to recognize new categories of images from a handful of examples, yet doing so with artificial ones remains an open challenge. We hypothesize that data-efficient recognition is enabled by representations which make the variability in natural signals more predictable. We therefore revisit and improve Contrastive Predictive Coding, an unsupervised objective for learning such representations. This new implementation produces features which support state-of-theart linear classification accuracy on the ImageNet dataset. When used as input for non-linear classification with deep neural networks, this representation allows us to use 2-5× less labels than classifiers trained directly on image pixels. Finally, this unsupervised representation substantially improves transfer learning to object detection on the PASCAL VOC dataset, surpassing fully supervised pre-trained ImageNet classifiers.

由于几个原因，很难聚集艺术品。一方面，识别基于领域知识和视觉感知的有意义的模式非常困难。另一方面，将传统的聚类和功能还原技术应用于高度尺寸的像素空间可能是无效的。为了解决这些问题，在本文中，我们提出了Delius：一种深入学习视觉艺术的深度学习方法。该方法使用预训练的卷积网络提取功能，然后将这些功能馈送到深层嵌入聚类模型中，在此，将输入数据映射到潜在空间的任务是通过在找到一组集群质心的任务，以在此任务进行优化。这个潜在空间。定量和定性实验结果表明了该方法的有效性。Delius对于与艺术分析有关的多个任务很有用，特别是在绘画数据集中发现的视觉链接检索和历史知识发现。

Current methods for training convolutional neural networks depend on large amounts of labeled samples for supervised training. In this paper we present an approach for training a convolutional neural network using only unlabeled data. We train the network to discriminate between a set of surrogate classes. Each surrogate class is formed by applying a variety of transformations to a randomly sampled 'seed' image patch. We find that this simple feature learning algorithm is surprisingly successful when applied to visual object recognition. The feature representation learned by our algorithm achieves classification results matching or outperforming the current state-of-the-art for unsupervised learning on several popular datasets (STL-10, CIFAR-10, Caltech-101).

Clustering is a class of unsupervised learning methods that has been extensively applied and studied in computer vision. Little work has been done to adapt it to the end-to-end training of visual features on large scale datasets. In this work, we present DeepCluster, a clustering method that jointly learns the parameters of a neural network and the cluster assignments of the resulting features. DeepCluster iteratively groups the features with a standard clustering algorithm, kmeans, and uses the subsequent assignments as supervision to update the weights of the network. We apply DeepCluster to the unsupervised training of convolutional neural networks on large datasets like ImageNet and YFCC100M. The resulting model outperforms the current state of the art by a significant margin on all the standard benchmarks.

我们解决了新颖的类发现问题，旨在根据可见类别的数据在未标记的数据中发现新的类。主要的挑战是将所见类中包含的知识转移到看不见的知识中。先前的方法主要通过共享表示空间或关节标签空间传输知识。但是，他们倾向于忽略可见类别和看不见的类别之间的阶级关系，因此学习的表示对聚类的看不见类别的有效性较差。在本文中，我们提出了一种原理和一般方法，以在可见的和看不见的阶级之间传递语义知识。我们的见解是利用共同的信息来衡量受限的标签空间中看到的类和看不见的类之间的关系，并最大化相互信息可以促进传递语义知识的传递。为了验证我们方法的有效性和概括，我们对新型类发现和一般新型类发现设置进行了广泛的实验。我们的结果表明，所提出的方法在几个基准上优于先前的SOTA。

The success of machine learning algorithms generally depends on data representation, and we hypothesize that this is because different representations can entangle and hide more or less the different explanatory factors of variation behind the data. Although specific domain knowledge can be used to help design representations, learning with generic priors can also be used, and the quest for AI is motivating the design of more powerful representation-learning algorithms implementing such priors. This paper reviews recent work in the area of unsupervised feature learning and deep learning, covering advances in probabilistic models, auto-encoders, manifold learning, and deep networks. This motivates longer-term unanswered questions about the appropriate objectives for learning good representations, for computing representations (i.e., inference), and the geometrical connections between representation learning, density estimation and manifold learning.

我们通过以端到端的方式对大规模未标记的数据集进行分类，呈现扭曲，简单和理论上可解释的自我监督的表示学习方法。我们使用Softmax操作终止的暹罗网络，以产生两个增强图像的双类分布。没有监督，我们强制执行不同增强的班级分布。但是，只需最小化增强之间的分歧将导致折叠解决方案，即，输出所有图像的相同类概率分布。在这种情况下，留下有关输入图像的信息。为了解决这个问题，我们建议最大化输入和课程预测之间的互信息。具体地，我们最小化每个样品的分布的熵，使每个样品的课程预测是对每个样品自信的预测，并最大化平均分布的熵，以使不同样品的预测变得不同。以这种方式，扭曲可以自然地避免没有特定设计的折叠解决方案，例如非对称网络，停止梯度操作或动量编码器。因此，扭曲优于各种任务的最先进的方法。特别是，在半监督学习中，扭曲令人惊讶地表现出令人惊讶的是，使用Reset-50作为骨干的1％ImageNet标签实现61.2％的顶级精度，以前的最佳结果为6.2％。代码和预先训练的模型是给出的：https://github.com/byteDance/twist