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Nowadays, multivariate time series data are increasingly collected in various real world systems, e.g., power plants, wearable devices, etc. Anomaly detection and diagnosis in multivariate time series refer to identifying abnormal status in…

In classification problems, supervised machine-learning methods outperform traditional algorithms, thanks to the ability of neural networks to learn complex patterns. However, in two-class classification tasks like anomaly or fraud…

Machine Learning · Computer Science 2022-04-01 Mihai-Cezar Augustin , Vivien Bonvin , Regis Houssou , Efstratios Rappos , Stephan Robert-Nicoud

Recently Autoencoder(AE) based models are widely used in the field of anomaly detection. A model trained with normal data generates a larger restoration error for abnormal data. Whether or not abnormal data is determined by observing the…

Machine Learning · Computer Science 2021-07-20 JoonSung Lee , YeongHyeon Park

Existing unsupervised distillation-based methods rely on the differences between encoded and decoded features to locate abnormal regions in test images. However, the decoder trained only on normal samples still reconstructs abnormal patch…

Computer Vision and Pattern Recognition · Computer Science 2025-01-03 Xiaolei Wang , Xiaoyang Wang , Huihui Bai , Eng Gee Lim , Jimin Xiao

In image anomaly detection, Autoencoders are the popular methods that reconstruct the input image that might contain anomalies and output a clean image with no abnormalities. These Autoencoder-based methods usually calculate the anomaly…

Image and Video Processing · Electrical Eng. & Systems 2021-05-24 Masaki Nakanishi , Kazuki Sato , Hideo Terada

Anomaly detection (AD) is a critical task across domains such as cybersecurity and healthcare. In the unsupervised setting, an effective and theoretically-grounded principle is to train classifiers to distinguish normal data from…

Machine Learning · Statistics 2025-06-18 Matthew Lau , Tian-Yi Zhou , Xiangchi Yuan , Jizhou Chen , Wenke Lee , Xiaoming Huo

Clustering is essential to many tasks in pattern recognition and computer vision. With the advent of deep learning, there is an increasing interest in learning deep unsupervised representations for clustering analysis. Many works on this…

Machine Learning · Computer Science 2018-02-02 Caglar Aytekin , Xingyang Ni , Francesco Cricri , Emre Aksu

Variational Auto-Encoders have often been used for unsupervised pretraining, feature extraction and out-of-distribution and anomaly detection in the medical field. However, VAEs often lack the ability to produce sharp images and learn…

Machine Learning · Computer Science 2019-11-28 David Zimmerer , Jens Petersen , Klaus Maier-Hein

Anomaly detection is commonly pursued as a one-class classification problem, where models can only learn from normal training samples, while being evaluated on both normal and abnormal test samples. Among the successful approaches for…

Computer Vision and Pattern Recognition · Computer Science 2022-03-15 Nicolae-Catalin Ristea , Neelu Madan , Radu Tudor Ionescu , Kamal Nasrollahi , Fahad Shahbaz Khan , Thomas B. Moeslund , Mubarak Shah

Anomaly detection to recognize unusual events in large scale systems in a time sensitive manner is critical in many industries, eg. bank fraud, enterprise systems, medical alerts, etc. Large-scale systems often grow in size and complexity…

Machine Learning · Computer Science 2022-10-31 Srishti Mishra , Tvarita Jain , Dinkar Sitaram

Unsupervised anomaly detection (UAD) aims to find anomalous images by optimising a detector using a training set that contains only normal images. UAD approaches can be based on reconstruction methods, self-supervised approaches, and…

Image and Video Processing · Electrical Eng. & Systems 2023-08-23 Yu Tian , Guansong Pang , Yuyuan Liu , Chong Wang , Yuanhong Chen , Fengbei Liu , Rajvinder Singh , Johan W Verjans , Mengyu Wang , Gustavo Carneiro

Our work focuses on tackling large-scale fine-grained image retrieval as ranking the images depicting the concept of interests (i.e., the same sub-category labels) highest based on the fine-grained details in the query. It is desirable to…

Information Retrieval · Computer Science 2023-11-23 Xiu-Shen Wei , Yang Shen , Xuhao Sun , Peng Wang , Yuxin Peng

In recent years, deep discriminative models have achieved extraordinary performance on supervised learning tasks, significantly outperforming their generative counterparts. However, their success relies on the presence of a large amount of…

Computer Vision and Pattern Recognition · Computer Science 2017-09-05 Gaurav Pandey , Ambedkar Dukkipati

Despite the rapid advance of unsupervised anomaly detection, existing methods require to train separate models for different objects. In this work, we present UniAD that accomplishes anomaly detection for multiple classes with a unified…

Computer Vision and Pattern Recognition · Computer Science 2022-10-26 Zhiyuan You , Lei Cui , Yujun Shen , Kai Yang , Xin Lu , Yu Zheng , Xinyi Le

In the research area of anomaly detection, novel and promising methods are frequently developed. However, most existing studies exclusively focus on the detection task only and ignore the interpretability of the underlying models as well as…

Machine Learning · Computer Science 2023-01-16 Cheng Feng , Pingge Hu

Anomaly detection is a challenging task that frequently arises in practically all areas of industry and science, from fraud detection and data quality monitoring to finding rare cases of diseases and searching for new physics. Most of the…

Machine Learning · Computer Science 2021-11-22 Artem Ryzhikov , Maxim Borisyak , Andrey Ustyuzhanin , Denis Derkach

Anomaly detection relies on designing a score to determine whether a particular event is uncharacteristic of a given background distribution. One way to define a score is to use autoencoders, which rely on the ability to reconstruct certain…

High Energy Physics - Phenomenology · Physics 2022-03-30 Katherine Fraser , Samuel Homiller , Rashmish K. Mishra , Bryan Ostdiek , Matthew D. Schwartz

Deep neural networks usually benefit from unsupervised pre-training, e.g. auto-encoders. However, the classifier further needs supervised fine-tuning methods for good discrimination. Besides, due to the limits of full-connection, the…

Computer Vision and Pattern Recognition · Computer Science 2016-05-10 Hailin Shi , Xiangyu Zhu , Zhen Lei , Shengcai Liao , Stan Z. Li

This paper proposes a method to ease the unsupervised learning of object landmark detectors. Similarly to previous methods, our approach is fully unsupervised in a sense that it does not require or make any use of annotated landmarks for…

Computer Vision and Pattern Recognition · Computer Science 2019-10-22 Enrique Sanchez , Georgios Tzimiropoulos

Despite inherent ill-definition, anomaly detection is a research endeavor of great interest within machine learning and visual scene understanding alike. Most commonly, anomaly detection is considered as the detection of outliers within a…

Computer Vision and Pattern Recognition · Computer Science 2019-05-03 Samet Akçay , Amir Atapour-Abarghouei , Toby P. Breckon