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Visual anomaly detection in real-world industrial settings faces two major limitations. First, most existing methods are trained on purely normal data or on unlabeled datasets assumed to be predominantly normal, presuming the absence of…

Computer Vision and Pattern Recognition · Computer Science 2026-02-05 Anindya Sundar Das , Monowar Bhuyan

Diffusion models have achieved significant progress in both image and video generation while still suffering from huge computation costs. As an effective solution, flow matching aims to reflow the diffusion process of diffusion models into…

Graphics · Computer Science 2025-03-13 Lei Ke , Haohang Xu , Xuefei Ning , Yu Li , Jiajun Li , Haoling Li , Yuxuan Lin , Dongsheng Jiang , Yujiu Yang , Linfeng Zhang

We introduce the task of human action anomaly detection (HAAD), which aims to identify anomalous motions in an unsupervised manner given only the pre-determined normal category of training action samples. Compared to prior human-related…

Computer Vision and Pattern Recognition · Computer Science 2024-04-29 Shun Maeda , Chunzhi Gu , Jun Yu , Shogo Tokai , Shangce Gao , Chao Zhang

Large displacement optical flow is an integral part of many computer vision tasks. Variational optical flow techniques based on a coarse-to-fine scheme interpolate sparse matches and locally optimize an energy model conditioned on colour,…

Computer Vision and Pattern Recognition · Computer Science 2022-06-28 Qiao Chen , Charalambos Poullis

Unsupervised optical flow estimators based on deep learning have attracted increasing attention due to the cost and difficulty of annotating for ground truth. Although performance measured by average End-Point Error (EPE) has improved over…

Computer Vision and Pattern Recognition · Computer Science 2022-08-05 Shuzhi Yu , Hannah Halin Kim , Shuai Yuan , Carlo Tomasi

We tackle unsupervised anomaly detection (UAD), a problem of detecting data that significantly differ from normal data. UAD is typically solved by using density estimation. Recently, deep neural network (DNN)-based density estimators, such…

Machine Learning · Statistics 2019-03-14 Masataka Yamaguchi , Yuma Koizumi , Noboru Harada

The business processes of organizations may deviate from normal control flow due to disruptive anomalies, including unknown, skipped, and wrongly-ordered activities. To identify these control-flow anomalies, process mining can check…

Machine Learning · Computer Science 2025-02-17 Francesco Vitale , Marco Pegoraro , Wil M. P. van der Aalst , Nicola Mazzocca

A Normalizing Flow computes a bijective mapping from an arbitrary distribution to a predefined (e.g. normal) distribution. Such a flow can be used to address different tasks, e.g. anomaly detection, once such a mapping has been learned. In…

Quantum Physics · Physics 2024-07-23 Bodo Rosenhahn , Christoph Hirche

Normalizing flow is a generative modeling approach with efficient sampling. However, Flow-based models suffer two issues: 1) If the target distribution is manifold, due to the unmatch between the dimensions of the latent target distribution…

Machine Learning · Computer Science 2024-04-24 Qinglong Meng , Chongkun Xia , Xueqian Wang

Unsupervised graph-level anomaly detection (UGAD) has attracted increasing interest due to its widespread application. In recent studies, knowledge distillation-based methods have been widely used in unsupervised anomaly detection to…

Machine Learning · Computer Science 2024-07-02 Rui Cao , Shijie Xue , Jindong Li , Qi Wang , Yi Chang

We study Variational Rectified Flow Matching, a framework that enhances classic rectified flow matching by modeling multi-modal velocity vector-fields. At inference time, classic rectified flow matching 'moves' samples from a source…

Machine Learning · Computer Science 2025-02-14 Pengsheng Guo , Alexander G. Schwing

Generating high-quality time-series data is challenging because real-world signals often exhibit multimodal patterns and multiscale dynamics, including oscillations and high-frequency variations. Flow Matching (FM) offers an efficient…

Machine Learning · Computer Science 2026-05-29 Junru Zhang , Lang Feng , Jinbo Wang , Xu Guo , Yucheng Wang , Han Yu , Min Wu , Yabo Dong , Duanqing Xu

In this paper, we propose $\text{HF}^2$-VAD, a Hybrid framework that integrates Flow reconstruction and Frame prediction seamlessly to handle Video Anomaly Detection. Firstly, we design the network of ML-MemAE-SC (Multi-Level Memory modules…

Computer Vision and Pattern Recognition · Computer Science 2021-08-17 Zhian Liu , Yongwei Nie , Chengjiang Long , Qing Zhang , Guiqing Li

In industrial manufacturing processes, errors frequently occur at unpredictable times and in unknown manifestations. We tackle the problem of automatic defect detection without requiring any image samples of defective parts. Recent works…

Computer Vision and Pattern Recognition · Computer Science 2021-10-07 Marco Rudolph , Tom Wehrbein , Bodo Rosenhahn , Bastian Wandt

Unsupervised anomaly detection stands as an important problem in machine learning, with applications in financial fraud prevention, network security and medical diagnostics. Existing unsupervised anomaly detection algorithms rarely perform…

Machine Learning · Computer Science 2026-02-04 Pritam Kar , Rahul Bordoloi , Olaf Wolkenhauer , Saptarshi Bej

Semi-supervised video anomaly detection (VAD) methods formulate the task of anomaly detection as detection of deviations from the learned normal patterns. Previous works in the field (reconstruction or prediction-based methods) suffer from…

Computer Vision and Pattern Recognition · Computer Science 2022-05-05 Mohammad Baradaran , Robert Bergevin

Anomaly Detection (AD), as a critical problem, has been widely discussed. In this paper, we specialize in one specific problem, Visual Defect Detection (VDD), in many industrial applications. And in practice, defect image samples are very…

Computer Vision and Pattern Recognition · Computer Science 2022-11-30 Yapeng Teng , Haoyang Li , Fuzhen Cai , Ming Shao , Siyu Xia

Flow matching (FM) learns vector fields by regressing stochastic velocity targets along intermediate distributions $p_t$. We identify a geometric optimization bottleneck in this regression problem: when the covariance $\Sigma_t$ of $p_t$ is…

Machine Learning · Computer Science 2026-05-14 Shadab Ahamed , Eshed Gal , Md Shahriar Rahim Siddiqui , Simon Ghyselincks , Moshe Eliasof , Eldad Haber

Multivariate time series anomaly detection has been extensively studied under the semi-supervised setting, where a training dataset with all normal instances is required. However, preparing such a dataset is very laborious since each single…

Machine Learning · Computer Science 2023-06-21 Qihang Zhou , Jiming Chen , Haoyu Liu , Shibo He , Wenchao Meng

Reconstructing a dynamic scene from image inputs is a fundamental computer vision task with many downstream applications. Despite recent advancements, existing approaches still struggle to achieve high-quality reconstructions from unseen…

Computer Vision and Pattern Recognition · Computer Science 2025-03-03 Sara Oblak , Despoina Paschalidou , Sanja Fidler , Matan Atzmon