During X-ray computed tomography (CT) scanning, metallic implants carrying with patients often lead to adverse artifacts in the captured CT images and then impair the clinical treatment. Against this metal artifact reduction (MAR) task, the existing deep-learning-based methods have gained promising reconstruction performance. Nevertheless, there is still some room for further improvement of MAR performance and generalization ability, since some important prior knowledge underlying this specific task has not been fully exploited. Hereby, in this paper, we carefully analyze the characteristics of metal artifacts and propose an orientation-shared convolution representation strategy to adapt the physical prior structures of artifacts, i.e., rotationally symmetrical streaking patterns. The proposed method rationally adopts Fourier-series-expansion-based filter parametrization in artifact modeling, which can better separate artifacts from anatomical tissues and boost the model generalizability. Comprehensive experiments executed on synthesized and clinical datasets show the superiority of our method in detail preservation beyond the current representative MAR methods. Code will be available at \url{https://github.com/hongwang01/OSCNet}
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The increasing privacy concerns on personal private text data promote the development of federated learning (FL) in recent years. However, the existing studies on applying FL in NLP are not suitable to coordinate participants with heterogeneous or private learning objectives. In this study, we further broaden the application scope of FL in NLP by proposing an Assign-Then-Contrast (denoted as ATC) framework, which enables clients with heterogeneous NLP tasks to construct an FL course and learn useful knowledge from each other. Specifically, the clients are suggested to first perform local training with the unified tasks assigned by the server rather than using their own learning objectives, which is called the Assign training stage. After that, in the Contrast training stage, clients train with different local learning objectives and exchange knowledge with other clients who contribute consistent and useful model updates. We conduct extensive experiments on six widely-used datasets covering both Natural Language Understanding (NLU) and Natural Language Generation (NLG) tasks, and the proposed ATC framework achieves significant improvements compared with various baseline methods. The source code is available at \url{https://github.com/alibaba/FederatedScope/tree/master/federatedscope/nlp/hetero_tasks}.
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胸部X射线(CXR)中准确的异常定位可以使各种胸部疾病的临床诊断受益。但是,病变水平的注释只能由经验丰富的放射科医生进行,这是乏味且耗时的,因此很难获得。这种情况导致难以开发CXR的完全监督异常定位系统。在这方面,我们建议通过一个弱半监督的策略来训练CXR异常本地化框架,称为“超越阶级”(PBC),该策略(PBC)使用了少数带有病变级别边界框的完全注释的CXR,并通过广泛的弱化的样品和大量的带有注释的样品。点。这样的点注释设置可以通过边缘注释成本提供弱实例级信息,以实现异常定位。尤其是,我们的PBC背后的核心思想是学习从点注释到边界框的强大而准确的映射,以根据注释点的差异。为此,提出了一个正则化项,即多点的一致性,它驱动模型从相同异常内的不同点注释中生成一致的边界框。此外,还提出了一种被称为对称的一致性的自学,也提出了从弱注释的数据中深入利用有用的信息来实现异常定位。 RSNA和VINDR-CXR数据集的实验结果证明了该方法的有效性。当使用少于20%的盒子级标签进行训练时,与当前的最新方法相比,我们的PBC可以在MAP中提高〜5的改进(即点DETR)。代码可从https://github.com/haozheliu-st/point-beyond-class获得。
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为了调查现实世界中联邦学习的异质性,我们将经典的联合学习概括为联合的异性任务学习,这强调了参与者在数据分布和学习任务方面的联盟学习中的不一致性。我们还提出了B-FHTL,这是一种联合的杂项任务学习基准,该基准包括模拟数据集,FL协议和统一的评估机制。 B-FHTL数据集包含三个精心设计的联合学习任务,异质性增加。每个任务都使用不同的非IID数据和学习任务模拟客户端。为了确保不同的FL算法之间的公平比较,B-FHTL通过提供高级API来避免隐私泄漏,在整个FL协议中构建,并预设跨越不同的学习任务的最常见评估指标,例如回归,分类,文本,文本,文本此外,我们还比较了B-FHTL中联合多任务学习,联合个性化和联合元学习领域的FL算法,并突出了联盟异质任务学习的异质性和困难的影响。我们的基准测试,包括联合数据集,协议,评估机制和初步实验,可在https://github.com/alibaba/federatedscope/tree/master/master/master/benchmark/b-fhtl上开放。
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联合学习(FL)的令人难以置信的发展使计算机视觉和自然语言处理领域的各种任务受益,而现有的TFF和FATE等现有框架使在现实应用程序中的部署变得容易。但是,即使图形数据很普遍,联合图形学习(FGL)由于其独特的特征和要求而没有得到很好的支持。缺乏与FGL相关的框架增加了完成可再现研究和在现实世界应用中部署的努力。在本文中,我们首先讨论了创建易于使用的FGL软件包的挑战,因此提出了我们实施的FederatedScope-GNN(FS-G)的包裹,该软件包提供了(1)统一的模块化视图并表达FGL算法; (2)用于开箱即用的FGL功能的综合数据和模型; (3)有效的模型自动调整组件; (4)现成的隐私攻击和防御能力。我们通过进行广泛的实验来验证FS-G的有效性,该实验同时获得了许多有关FGL的宝贵见解。此外,我们采用FS-G在现实世界中的电子商务方案中为FGL应用程序提供服务,在该场景中获得的改进表明了巨大的潜在业务利益。我们在https://github.com/alibaba/federatedscope上公开发布FS-G,作为FederatedScope的子模型,以促进FGL的研究,并启用由于缺乏专用包装而无法无视的广泛应用。
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尽管现有联合学习平台(FL)平台已取得了显着的进展,以提供开发基础架构,但这些平台可能无法很好地应对各种异质性带来的挑战,包括参与者本地数据,资源,行为和学习目标中的异质性。为了填补这一空白,在本文中,我们提出了一个名为FederatedScope的新型FL平台,该平台采用事件驱动的架构为用户提供极大的灵活性,以独立描述不同参与者的行为。这样的设计使用户可以轻松地描述参与者具有各种本地培训过程,学习目标和后端,并通过同步或异步培训策略将其协调为FL课程。 FederatedScope为易于使用和灵活的平台提供了丰富类型的插入操作和组件,以有效地进行进一步开发,并且我们实施了几个重要组件,以更好地帮助用户进行隐私保护,攻击模拟和自动调整。我们已经在https://github.com/alibaba/federatedscope上发布了FederatedScope,以在各种情况下促进联邦学习的学术研究和工业部署。
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As a common weather, rain streaks adversely degrade the image quality. Hence, removing rains from an image has become an important issue in the field. To handle such an ill-posed single image deraining task, in this paper, we specifically build a novel deep architecture, called rain convolutional dictionary network (RCDNet), which embeds the intrinsic priors of rain streaks and has clear interpretability. In specific, we first establish a RCD model for representing rain streaks and utilize the proximal gradient descent technique to design an iterative algorithm only containing simple operators for solving the model. By unfolding it, we then build the RCDNet in which every network module has clear physical meanings and corresponds to each operation involved in the algorithm. This good interpretability greatly facilitates an easy visualization and analysis on what happens inside the network and why it works well in inference process. Moreover, taking into account the domain gap issue in real scenarios, we further design a novel dynamic RCDNet, where the rain kernels can be dynamically inferred corresponding to input rainy images and then help shrink the space for rain layer estimation with few rain maps so as to ensure a fine generalization performance in the inconsistent scenarios of rain types between training and testing data. By end-to-end training such an interpretable network, all involved rain kernels and proximal operators can be automatically extracted, faithfully characterizing the features of both rain and clean background layers, and thus naturally lead to better deraining performance. Comprehensive experiments substantiate the superiority of our method, especially on its well generality to diverse testing scenarios and good interpretability for all its modules. Code is available in \emph{\url{https://github.com/hongwang01/DRCDNet}}.
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Transformer has achieved impressive successes for various computer vision tasks. However, most of existing studies require to pretrain the Transformer backbone on a large-scale labeled dataset (e.g., ImageNet) for achieving satisfactory performance, which is usually unavailable for medical images. Additionally, due to the gap between medical and natural images, the improvement generated by the ImageNet pretrained weights significantly degrades while transferring the weights to medical image processing tasks. In this paper, we propose Bootstrap Own Latent of Transformer (BOLT), a self-supervised learning approach specifically for medical image classification with the Transformer backbone. Our BOLT consists of two networks, namely online and target branches, for self-supervised representation learning. Concretely, the online network is trained to predict the target network representation of the same patch embedding tokens with a different perturbation. To maximally excavate the impact of Transformer from limited medical data, we propose an auxiliary difficulty ranking task. The Transformer is enforced to identify which branch (i.e., online/target) is processing the more difficult perturbed tokens. Overall, the Transformer endeavours itself to distill the transformation-invariant features from the perturbed tokens to simultaneously achieve difficulty measurement and maintain the consistency of self-supervised representations. The proposed BOLT is evaluated on three medical image processing tasks, i.e., skin lesion classification, knee fatigue fracture grading and diabetic retinopathy grading. The experimental results validate the superiority of our BOLT for medical image classification, compared to ImageNet pretrained weights and state-of-the-art self-supervised learning approaches.
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Driven by improved architectures and better representation learning frameworks, the field of visual recognition has enjoyed rapid modernization and performance boost in the early 2020s. For example, modern ConvNets, represented by ConvNeXt, have demonstrated strong performance in various scenarios. While these models were originally designed for supervised learning with ImageNet labels, they can also potentially benefit from self-supervised learning techniques such as masked autoencoders (MAE). However, we found that simply combining these two approaches leads to subpar performance. In this paper, we propose a fully convolutional masked autoencoder framework and a new Global Response Normalization (GRN) layer that can be added to the ConvNeXt architecture to enhance inter-channel feature competition. This co-design of self-supervised learning techniques and architectural improvement results in a new model family called ConvNeXt V2, which significantly improves the performance of pure ConvNets on various recognition benchmarks, including ImageNet classification, COCO detection, and ADE20K segmentation. We also provide pre-trained ConvNeXt V2 models of various sizes, ranging from an efficient 3.7M-parameter Atto model with 76.7% top-1 accuracy on ImageNet, to a 650M Huge model that achieves a state-of-the-art 88.9% accuracy using only public training data.
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A step-search sequential quadratic programming method is proposed for solving nonlinear equality constrained stochastic optimization problems. It is assumed that constraint function values and derivatives are available, but only stochastic approximations of the objective function and its associated derivatives can be computed via inexact probabilistic zeroth- and first-order oracles. Under reasonable assumptions, a high-probability bound on the iteration complexity of the algorithm to approximate first-order stationarity is derived. Numerical results on standard nonlinear optimization test problems illustrate the advantages and limitations of our proposed method.
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