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Among the many challenges posed by the huge data volumes produced by the new generation of astronomical instruments there is also the search for rare and peculiar objects. Unsupervised outlier detection algorithms may provide a viable…

Instrumentation and Methods for Astrophysics · Physics 2021-05-12 Lars Doorenbos , Stefano Cavuoti , Massimo Brescia , Antonio D'Isanto , Giuseppe Longo

In this paper, we propose a novel approach for outlier detection, called local projections, which is based on concepts of Local Outlier Factor (LOF) (Breunig et al., 2000) and RobPCA (Hubert et al., 2005). By using aspects of both methods,…

Event sequence data record the occurrences of events in continuous time. Event sequence forecasting based on temporal point processes (TPPs) has been extensively studied, but outlier or anomaly detection, especially without any supervision…

Machine Learning · Computer Science 2024-11-26 Somjit Nath , Yik Chau Lui , Siqi Liu

One commonly used clinical approach towards detecting melanomas recognises the existence of Ugly Duckling nevi, or skin lesions which look different from the other lesions on the same patient. An automatic method of detecting and analysing…

Computer Vision and Pattern Recognition · Computer Science 2021-05-18 Mohammadreza Mohseni , Jordan Yap , William Yolland , Arash Koochek , M Stella Atkins

This study addresses an important gap in time series outlier detection by proposing a novel problem setting: long-term outlier prediction. Conventional methods primarily focus on immediate detection by identifying deviations from normal…

This study investigates the effectiveness of unsupervised outlier detection methods in audit analytics, utilizing USA spending data from the U.S. Department of Health and Human Services (DHHS) as a case example. We employ and compare…

Machine Learning · Computer Science 2025-09-25 Buhe Li , Berkay Kaplan , Maksym Lazirko , Aleksandr Kogan

We introduce and develop a novel approach to outlier detection based on adaptation of random subspace learning. Our proposed method handles both high-dimension low-sample size and traditional low-dimensional high-sample size datasets.…

Machine Learning · Statistics 2015-05-05 Bohan Liu , Ernest Fokoue

When deployed in practical applications, computer vision systems will encounter numerous unexpected images (\emph{{i.e.}}, out-of-distribution data). Due to the potentially raised safety risks, these aforementioned unseen data should be…

Computer Vision and Pattern Recognition · Computer Science 2024-01-19 Sen Pei , Jiaxi Sun , Richard Yi Da Xu , Bin Fan , Shiming Xiang , Gaofeng Meng

With the sweeping digitalization of societal, medical, industrial, and scientific processes, sensing technologies are being deployed that produce increasing volumes of time series data, thus fueling a plethora of new or improved…

Machine Learning · Computer Science 2024-04-23 David Campos , Tung Kieu , Chenjuan Guo , Feiteng Huang , Kai Zheng , Bin Yang , Christian S. Jensen

Outlier detection algorithms typically assign an outlier score to each observation in a dataset, indicating the degree to which an observation is an outlier. However, these scores are often not comparable across algorithms and can be…

Machine Learning · Computer Science 2024-10-31 Philipp Röchner , Henrique O. Marques , Ricardo J. G. B. Campello , Arthur Zimek , Franz Rothlauf

Out-of-distribution (OOD) detection plays a crucial role in ensuring the robustness and reliability of machine learning systems deployed in real-world applications. Recent approaches have explored the use of unlabeled data, showing…

Machine Learning · Computer Science 2025-10-09 Momin Abbas , Ali Falahati , Hossein Goli , Mohammad Mohammadi Amiri

The scores of distance-based outlier detection methods are difficult to interpret, making it challenging to determine a cut-off threshold between normal and outlier data points without additional context. We describe a generic…

Machine Learning · Computer Science 2023-07-20 David Muhr , Michael Affenzeller , Josef Küng

Discriminative learning effectively predicts true object class for image classification. However, it often results in false positives for outliers, posing critical concerns in applications like autonomous driving and video surveillance…

Computer Vision and Pattern Recognition · Computer Science 2024-06-04 Masoud Taghikhah , Nishant Kumar , Siniša Šegvić , Abouzar Eslami , Stefan Gumhold

Outlier detection is a core task in data mining with a plethora of algorithms that have enjoyed wide scale usage. Existing algorithms are primarily focused on detection, that is the identification of outliers in a given dataset. In this…

Machine Learning · Computer Science 2019-11-11 Yue Wu , Leman Akoglu , Ian Davidson

Out-of-distribution (OOD) detection, crucial for reliable pattern classification, discerns whether a sample originates outside the training distribution. This paper concentrates on the high-dimensional features output by the final…

Computer Vision and Pattern Recognition · Computer Science 2024-05-06 Qiuyu Zhu , Yiwei He

Deep convolutional models often produce inadequate predictions for inputs foreign to the training distribution. Consequently, the problem of detecting outlier images has recently been receiving a lot of attention. Unlike most previous work,…

Computer Vision and Pattern Recognition · Computer Science 2024-03-13 Petra Bevandić , Ivan Krešo , Marin Oršić , Siniša Šegvić

Outlier detection and novelty detection are two important topics for anomaly detection. Suppose the majority of a dataset are drawn from a certain distribution, outlier detection and novelty detection both aim to detect data samples that do…

Machine Learning · Computer Science 2019-11-19 Min Du , Ruoxi Jia , Dawn Song

Out-of-distribution (OOD) detection methods often exploit auxiliary outliers to train model identifying OOD samples, especially discovering challenging outliers from auxiliary outliers dataset to improve OOD detection. However, they may…

Computer Vision and Pattern Recognition · Computer Science 2024-03-25 Yichen Bai , Zongbo Han , Changqing Zhang , Bing Cao , Xiaoheng Jiang , Qinghua Hu

In this work, we present a new unsupervised anomaly (outlier) detection (AD) method using the sliced-Wasserstein metric. This filtering technique is conceptually interesting for MLOps pipelines deploying machine learning models in critical…

Machine Learning · Computer Science 2024-12-03 Julien Pallage , Bertrand Scherrer , Salma Naccache , Christophe Bélanger , Antoine Lesage-Landry

The accuracy of machine learning interatomic potentials suffers from reference data that contains numerical noise. Often originating from unconverged or inconsistent electronic-structure calculations, this noise is challenging to identify.…

Machine Learning · Statistics 2026-02-10 Terry C. W. Lam , Niamh O'Neill , Christoph Schran , Lars L. Schaaf