机器的图像编码(ICM)旨在压缩图像进行AI任务分析,而不是满足人类的看法。学习一种既是一般(用于AI任务)的特征,也是紧凑的(用于压缩)的功能,这对于其成功而言至关重要。在本文中,我们试图通过学习通用功能,同时考虑压缩来开发ICM框架。我们将诸如无所不能功能和相应框架的功能命名为Omni-ICM。考虑到自我监督学习(SSL)提高了特征的概括,我们将其与压缩任务集成到OMNI-ICM框架中,以学习无所不能的功能。但是,在SSL中协调语义建模并在压缩中删除冗余是不平凡的,因此我们通过合作实例区分和熵最小化以自适应掉落的信息来设计新颖的信息过滤(如果)模块,以较弱相关的信息执行AI任务(例如,某些纹理冗余)。与以前的特定解决方案不同,Omni-ICM可以直接基于学习的无能功能的AI任务分析,而无需联合培训或额外的转换。尽管简单而直观,但Omni-ICM在多个基本愿景任务上大大优于现有的传统和基于学习的编解码器。
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在本文中,我们介绍了第一个神经视频编解码器,可以在用于低延迟模式的UVG数据集上的SRGB PSNR方面与最新编码标准H.266 / VVC竞争。现有的神经混合视频编码方法依赖于用于预测的光流或高斯尺度流,这不能支持对不同运动内容的细粒度适应性。为了更具内容 - 自适应预测,我们提出了一种新颖的跨尺度预测模块,实现更有效的运动补偿。具体地,一方面,我们生产参考特征金字塔作为预测源,然后传输利用特征尺度的横级流来控制预测的精度。另一方面,我们将加权预测的机制介绍到具有单个参考帧的预测场景的机制,其中发送交叉尺度权重映射以合成精细预测结果。除了串尺度预测模块之外,我们还提出了一种多级量化策略,这提高了在推理期间没有额外计算惩罚的速率失真性能。我们展示了我们有效的神经视频编解码器(ENVC)对几个常见的基准数据集的令人鼓舞的表现,并详细分析了每个重要组成部分的有效性。
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学习的视频压缩方法在赶上其速率 - 失真(R-D)性能时,追赶传统视频编解码器的许多承诺。然而,现有的学习视频压缩方案受预测模式和固定网络框架的绑定限制。它们无法支持各种帧间预测模式,从而不适用于各种场景。在本文中,为了打破这种限制,我们提出了一种多功能学习的视频压缩(VLVC)框架,它使用一个模型来支持所有可能的预测模式。具体而言,为了实现多功能压缩,我们首先构建一个运动补偿模块,该模块应用用于在空间空间中的加权三线性翘曲的多个3D运动矢量字段(即,Voxel流量)。 Voxel流量传达了时间参考位置的信息,有助于与框架设计中的帧间预测模式分离。其次,在多参考帧预测的情况下,我们应用流预测模块以预测具有统一多项式函数的准确运动轨迹。我们表明流量预测模块可以大大降低体素流的传输成本。实验结果表明,我们提出的VLVC不仅支持各种设置中的多功能压缩,而且还通过MS-SSIM的最新VVC标准实现了可比的R-D性能。
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Blind image quality assessment (BIQA) remains challenging due to the diversity of distortion and image content variation, which complicate the distortion patterns crossing different scales and aggravate the difficulty of the regression problem for BIQA. However, existing BIQA methods often fail to consider multi-scale distortion patterns and image content, and little research has been done on learning strategies to make the regression model produce better performance. In this paper, we propose a simple yet effective Progressive Multi-Task Image Quality Assessment (PMT-IQA) model, which contains a multi-scale feature extraction module (MS) and a progressive multi-task learning module (PMT), to help the model learn complex distortion patterns and better optimize the regression issue to align with the law of human learning process from easy to hard. To verify the effectiveness of the proposed PMT-IQA model, we conduct experiments on four widely used public datasets, and the experimental results indicate that the performance of PMT-IQA is superior to the comparison approaches, and both MS and PMT modules improve the model's performance.
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It has been observed in practice that applying pruning-at-initialization methods to neural networks and training the sparsified networks can not only retain the testing performance of the original dense models, but also sometimes even slightly boost the generalization performance. Theoretical understanding for such experimental observations are yet to be developed. This work makes the first attempt to study how different pruning fractions affect the model's gradient descent dynamics and generalization. Specifically, this work considers a classification task for overparameterized two-layer neural networks, where the network is randomly pruned according to different rates at the initialization. It is shown that as long as the pruning fraction is below a certain threshold, gradient descent can drive the training loss toward zero and the network exhibits good generalization performance. More surprisingly, the generalization bound gets better as the pruning fraction gets larger. To complement this positive result, this work further shows a negative result: there exists a large pruning fraction such that while gradient descent is still able to drive the training loss toward zero (by memorizing noise), the generalization performance is no better than random guessing. This further suggests that pruning can change the feature learning process, which leads to the performance drop of the pruned neural network. Up to our knowledge, this is the \textbf{first} generalization result for pruned neural networks, suggesting that pruning can improve the neural network's generalization.
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Time-series anomaly detection is an important task and has been widely applied in the industry. Since manual data annotation is expensive and inefficient, most applications adopt unsupervised anomaly detection methods, but the results are usually sub-optimal and unsatisfactory to end customers. Weak supervision is a promising paradigm for obtaining considerable labels in a low-cost way, which enables the customers to label data by writing heuristic rules rather than annotating each instance individually. However, in the time-series domain, it is hard for people to write reasonable labeling functions as the time-series data is numerically continuous and difficult to be understood. In this paper, we propose a Label-Efficient Interactive Time-Series Anomaly Detection (LEIAD) system, which enables a user to improve the results of unsupervised anomaly detection by performing only a small amount of interactions with the system. To achieve this goal, the system integrates weak supervision and active learning collaboratively while generating labeling functions automatically using only a few labeled data. All of these techniques are complementary and can promote each other in a reinforced manner. We conduct experiments on three time-series anomaly detection datasets, demonstrating that the proposed system is superior to existing solutions in both weak supervision and active learning areas. Also, the system has been tested in a real scenario in industry to show its practicality.
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As an important variant of entity alignment (EA), multi-modal entity alignment (MMEA) aims to discover identical entities across different knowledge graphs (KGs) with multiple modalities like images. However, current MMEA algorithms all adopt KG-level modality fusion strategies but ignore modality differences among individual entities, hurting the robustness to potential noise involved in modalities (e.g., unidentifiable images and relations). In this paper we present MEAformer, a multi-modal entity alignment transformer approach for meta modality hybrid, to dynamically predict the mutual correlation coefficients among modalities for instance-level feature fusion. A modal-aware hard entity replay strategy is also proposed for addressing vague entity details. Extensive experimental results show that our model not only achieves SOTA performance on multiple training scenarios including supervised, unsupervised, iterative, and low resource, but also has limited parameters, optimistic speed, and good interpretability. Our code will be available soon.
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The task of video prediction and generation is known to be notoriously difficult, with the research in this area largely limited to short-term predictions. Though plagued with noise and stochasticity, videos consist of features that are organised in a spatiotemporal hierarchy, different features possessing different temporal dynamics. In this paper, we introduce Dynamic Latent Hierarchy (DLH) -- a deep hierarchical latent model that represents videos as a hierarchy of latent states that evolve over separate and fluid timescales. Each latent state is a mixture distribution with two components, representing the immediate past and the predicted future, causing the model to learn transitions only between sufficiently dissimilar states, while clustering temporally persistent states closer together. Using this unique property, DLH naturally discovers the spatiotemporal structure of a dataset and learns disentangled representations across its hierarchy. We hypothesise that this simplifies the task of modeling temporal dynamics of a video, improves the learning of long-term dependencies, and reduces error accumulation. As evidence, we demonstrate that DLH outperforms state-of-the-art benchmarks in video prediction, is able to better represent stochasticity, as well as to dynamically adjust its hierarchical and temporal structure. Our paper shows, among other things, how progress in representation learning can translate into progress in prediction tasks.
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Implicit regularization is an important way to interpret neural networks. Recent theory starts to explain implicit regularization with the model of deep matrix factorization (DMF) and analyze the trajectory of discrete gradient dynamics in the optimization process. These discrete gradient dynamics are relatively small but not infinitesimal, thus fitting well with the practical implementation of neural networks. Currently, discrete gradient dynamics analysis has been successfully applied to shallow networks but encounters the difficulty of complex computation for deep networks. In this work, we introduce another discrete gradient dynamics approach to explain implicit regularization, i.e. landscape analysis. It mainly focuses on gradient regions, such as saddle points and local minima. We theoretically establish the connection between saddle point escaping (SPE) stages and the matrix rank in DMF. We prove that, for a rank-R matrix reconstruction, DMF will converge to a second-order critical point after R stages of SPE. This conclusion is further experimentally verified on a low-rank matrix reconstruction problem. This work provides a new theory to analyze implicit regularization in deep learning.
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Gradient-based explanation is the cornerstone of explainable deep networks, but it has been shown to be vulnerable to adversarial attacks. However, existing works measure the explanation robustness based on $\ell_p$-norm, which can be counter-intuitive to humans, who only pay attention to the top few salient features. We propose explanation ranking thickness as a more suitable explanation robustness metric. We then present a new practical adversarial attacking goal for manipulating explanation rankings. To mitigate the ranking-based attacks while maintaining computational feasibility, we derive surrogate bounds of the thickness that involve expensive sampling and integration. We use a multi-objective approach to analyze the convergence of a gradient-based attack to confirm that the explanation robustness can be measured by the thickness metric. We conduct experiments on various network architectures and diverse datasets to prove the superiority of the proposed methods, while the widely accepted Hessian-based curvature smoothing approaches are not as robust as our method.
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