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Self-supervised instance discrimination is an effective contrastive pretext task to learn feature representations and address limited medical image annotations. The idea is to make features of transformed versions of the same images similar…

Computer Vision and Pattern Recognition · Computer Science 2022-11-17 Yejia Zhang , Xinrong Hu , Nishchal Sapkota , Yiyu Shi , Danny Z. Chen

We develop a self-supervised method for density-based anomaly detection using contrastive learning, and test it using event-level anomaly data from CMS ADC2021. The AnomalyCLR technique is data-driven and uses augmentations of the…

High Energy Physics - Phenomenology · Physics 2024-10-29 Barry M. Dillon , Luigi Favaro , Friedrich Feiden , Tanmoy Modak , Tilman Plehn

One main challenge in time series anomaly detection (TSAD) is the lack of labelled data in many real-life scenarios. Most of the existing anomaly detection methods focus on learning the normal behaviour of unlabelled time series in an…

Machine Learning · Computer Science 2024-09-04 Zahra Zamanzadeh Darban , Geoffrey I. Webb , Shirui Pan , Charu C. Aggarwal , Mahsa Salehi

Video Anomaly Detection (VAD) remains a fundamental yet formidable task in the video understanding community, with promising applications in areas such as information forensics and public safety protection. Due to the rarity and diversity…

Computer Vision and Pattern Recognition · Computer Science 2025-03-25 Yang Liu , Hongjin Wang , Zepu Wang , Xiaoguang Zhu , Jing Liu , Peng Sun , Rui Tang , Jianwei Du , Victor C. M. Leung , Liang Song

Generalist Anomaly Detection (GAD) aims to train a unified model on an original domain that can detect anomalies in new target domains. Previous GAD methods primarily use only normal samples as references, overlooking the valuable…

Computer Vision and Pattern Recognition · Computer Science 2025-10-20 Yuexin Wang , Xiaolei Wang , Yizheng Gong , Jimin Xiao

This paper presents Prototypical Contrastive Learning (PCL), an unsupervised representation learning method that addresses the fundamental limitations of instance-wise contrastive learning. PCL not only learns low-level features for the…

Computer Vision and Pattern Recognition · Computer Science 2021-03-31 Junnan Li , Pan Zhou , Caiming Xiong , Steven C. H. Hoi

The success of deep learning heavily depends on the availability of large labeled training sets. However, it is hard to get large labeled datasets in medical image domain because of the strict privacy concern and costly labeling efforts.…

Computer Vision and Pattern Recognition · Computer Science 2021-09-30 Dewen Zeng , Yawen Wu , Xinrong Hu , Xiaowei Xu , Haiyun Yuan , Meiping Huang , Jian Zhuang , Jingtong Hu , Yiyu Shi

The task of graph-level anomaly detection (GLAD) is to identify anomalous graphs that deviate significantly from the majority of graphs in a dataset. While deep GLAD methods have shown promising performance, their black-box nature limits…

Machine Learning · Computer Science 2026-02-12 Qiuran Zhao , Kai Ming Ting , Xinpeng Li

Contrastive learning (CL) aims to learn useful representation without relying on expert annotations in the context of medical image segmentation. Existing approaches mainly contrast a single positive vector (i.e., an augmentation of the…

Computer Vision and Pattern Recognition · Computer Science 2022-03-08 Chenyu You , Ruihan Zhao , Lawrence Staib , James S. Duncan

For anomaly detection (AD), early approaches often train separate models for individual classes, yielding high performance but posing challenges in scalability and resource management. Recent efforts have shifted toward training a single…

Computer Vision and Pattern Recognition · Computer Science 2025-07-18 Lei Fan , Junjie Huang , Donglin Di , Anyang Su , Tianyou Song , Maurice Pagnucco , Yang Song

There have been significant advancements in anomaly detection in an unsupervised manner, where only normal images are available for training. Several recent methods aim to detect anomalies based on a memory, comparing or reconstructing the…

Computer Vision and Pattern Recognition · Computer Science 2024-07-25 Joo Chan Lee , Taejune Kim , Eunbyung Park , Simon S. Woo , Jong Hwan Ko

Anomaly detection is a classical problem in computer vision, namely the determination of the normal from the abnormal when datasets are highly biased towards one class (normal) due to the insufficient sample size of the other class…

Computer Vision and Pattern Recognition · Computer Science 2018-11-14 Samet Akcay , Amir Atapour-Abarghouei , Toby P. Breckon

Local discriminative representation is needed in many medical image analysis tasks such as identifying sub-types of lesion or segmenting detailed components of anatomical structures. However, the commonly applied supervised representation…

Computer Vision and Pattern Recognition · Computer Science 2021-03-25 Huai Chen , Jieyu Li , Renzhen Wang , Yijie Huang , Fanrui Meng , Deyu Meng , Qing Peng , Lisheng Wang

Supervised anomaly detection methods perform well in identifying known anomalies that are well represented in the training set. However, they often struggle to generalise beyond the training distribution due to decision boundaries that lack…

Machine Learning · Computer Science 2025-11-18 Zahra Zamanzadeh Darban , Qizhou Wang , Charu C. Aggarwal , Geoffrey I. Webb , Ehsan Abbasnejad , Mahsa Salehi

Graph representation learning has attracted a surge of interest recently, whose target at learning discriminant embedding for each node in the graph. Most of these representation methods focus on supervised learning and heavily depend on…

Machine Learning · Computer Science 2021-07-07 Pengpeng Shao , Tong Liu , Dawei Zhang , Jianhua Tao , Feihu Che , Guohua Yang

Image manipulation detection and localization have received considerable attention from the research community given the blooming of Generative Models (GMs). Detection methods that follow a passive approach may overfit to specific GMs,…

Computer Vision and Pattern Recognition · Computer Science 2024-09-27 Filippo Bartolucci , Iacopo Masi , Giuseppe Lisanti

Tremendous breakthroughs have been developed in Semi-Supervised Semantic Segmentation (S4) through contrastive learning. However, due to limited annotations, the guidance on unlabeled images is generated by the model itself, which…

Computer Vision and Pattern Recognition · Computer Science 2024-02-29 Haoyu Xie , Changqi Wang , Jian Zhao , Yang Liu , Jun Dan , Chong Fu , Baigui Sun

Anomalies are samples that significantly deviate from the rest of the data and their detection plays a major role in building machine learning models that can be reliably used in applications such as data-driven design and novelty…

Machine Learning · Statistics 2023-06-19 Amin Yousefpour , Mehdi Shishehbor , Zahra Zanjani Foumani , Ramin Bostanabad

Representation learning offers a conduit to elucidate distinctive features within the latent space and interpret the deep models. However, the randomness of lesion distribution and the complexity of low-quality factors in medical images…

Computer Vision and Pattern Recognition · Computer Science 2024-04-09 Qingshan Hou , Shuai Cheng , Peng Cao , Jinzhu Yang , Xiaoli Liu , Osmar R. Zaiane , Yih Chung Tham

For medical image segmentation, contrastive learning is the dominant practice to improve the quality of visual representations by contrasting semantically similar and dissimilar pairs of samples. This is enabled by the observation that…

Computer Vision and Pattern Recognition · Computer Science 2023-10-25 Chenyu You , Weicheng Dai , Yifei Min , Fenglin Liu , David A. Clifton , S Kevin Zhou , Lawrence Hamilton Staib , James S Duncan