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Variational autoencoders learn unsupervised data representations, but these models frequently converge to minima that fail to preserve meaningful semantic information. For example, variational autoencoders with autoregressive decoders often…

Machine Learning · Computer Science 2019-05-21 Bryan Seybold , Emily Fertig , Alex Alemi , Ian Fischer

This paper presents a fast and principled approach for solving the visual anomaly detection and segmentation problem. In this setup, we have access to only anomaly-free training data and want to detect and identify anomalies of an arbitrary…

Computer Vision and Pattern Recognition · Computer Science 2022-11-24 Ibrahima Ndiour , Nilesh Ahuja , Utku Genc , Omesh Tickoo

Autoencoder and its variants have been widely applicated in anomaly detection.The previous work memory-augmented deep autoencoder proposed memorizing normality to detect anomaly, however it neglects the feature discrepancy between different…

Computer Vision and Pattern Recognition · Computer Science 2020-12-22 Yifei Yang , Shibing Xiang , Ruixiang Zhang

Due to their unsupervised training and uncertainty estimation, deep Variational Autoencoders (VAEs) have become powerful tools for reconstruction-based Time Series Anomaly Detection (TSAD). Existing VAE-based TSAD methods, either…

Machine Learning · Computer Science 2024-01-09 Zhangkai Wu , Longbing Cao , Qi Zhang , Junxian Zhou , Hui Chen

A Distributed Denial-of-service (DDoS) attack is a malicious attempt to disrupt the regular traffic of a targeted server, service, or network by sending a flood of traffic to overwhelm the target or its surrounding infrastructure. As…

Cryptography and Security · Computer Science 2023-05-17 Yuanyuan Wei , Julian Jang-Jaccard , Fariza Sabrina , Wen Xu , Seyit Camtepe , Aeryn Dunmore

Current unsupervised anomaly localization approaches rely on generative models to learn the distribution of normal images, which is later used to identify potential anomalous regions derived from errors on the reconstructed images. However,…

Image and Video Processing · Electrical Eng. & Systems 2021-10-29 Julio Silva-Rodríguez , Valery Naranjo , Jose Dolz

Autoencoders (AE) are simple yet powerful class of neural networks that compress data by projecting input into low-dimensional latent space (LS). Whereas LS is formed according to the loss function minimization during training, its…

Computer Vision and Pattern Recognition · Computer Science 2025-08-28 Nikita Gabdullin

We propose an out-of-distribution detection method that combines density and restoration-based approaches using Vector-Quantized Variational Auto-Encoders (VQ-VAEs). The VQ-VAE model learns to encode images in a categorical latent space.…

Computer Vision and Pattern Recognition · Computer Science 2020-12-15 Sergio Naval Marimont , Giacomo Tarroni

Significant advances in utilizing deep learning for anomaly detection have been made in recent years. However, these methods largely assume the existence of a normal training set (i.e., uncontaminated by anomalies) or even a completely…

Accelerator Physics · Physics 2023-09-06 Ryan Humble , William Colocho , Finn O'Shea , Daniel Ratner , Eric Darve

Variational auto-encoders (VAEs) provide an attractive solution to image generation problem. However, they tend to produce blurred and over-smoothed images due to their dependence on pixel-wise reconstruction loss. This paper introduces a…

Computer Vision and Pattern Recognition · Computer Science 2018-04-30 Salman H. Khan , Munawar Hayat , Nick Barnes

Exploiting the rapid advances in probabilistic inference, in particular variational Bayes and variational autoencoders (VAEs), for anomaly detection (AD) tasks remains an open research question. Previous works argued that training VAE…

Machine Learning · Computer Science 2020-10-13 Adrian Alan Pol , Victor Berger , Gianluca Cerminara , Cecile Germain , Maurizio Pierini

The weights of neural networks (NNs) have recently gained prominence as a new data modality in machine learning, with applications ranging from accuracy and hyperparameter prediction to representation learning or weight generation. One…

Machine Learning · Computer Science 2025-03-24 Léo Meynent , Ivan Melev , Konstantin Schürholt , Göran Kauermann , Damian Borth

As a substantial amount of multivariate time series data is being produced by the complex systems in Smart Manufacturing, improved anomaly detection frameworks are needed to reduce the operational risks and the monitoring burden placed on…

Machine Learning · Computer Science 2022-01-25 Tareq Tayeh , Sulaiman Aburakhia , Ryan Myers , Abdallah Shami

The joint optimization of the reconstruction and classification error is a hard non convex problem, especially when a non linear mapping is utilized. In order to overcome this obstacle, a novel optimization strategy is proposed, in which a…

Machine Learning · Computer Science 2022-11-07 Ioannis A. Nellas , Sotiris K. Tasoulis , Vassilis P. Plagianakos , Spiros V. Georgakopoulos

This paper presents an anomaly detection model that combines the strong statistical foundation of density-estimation-based anomaly detection methods with the representation-learning ability of deep-learning models. The method combines an…

Machine Learning · Computer Science 2022-11-17 Joseph Gallego-Mejia , Oscar Bustos-Brinez , Fabio A. González

Unsupervised anomaly detection (UAD) learns one-class classifiers exclusively with normal (i.e., healthy) images to detect any abnormal (i.e., unhealthy) samples that do not conform to the expected normal patterns. UAD has two main…

Computer Vision and Pattern Recognition · Computer Science 2021-07-01 Yu Tian , Guansong Pang , Fengbei Liu , Yuanhong chen , Seon Ho Shin , Johan W. Verjans , Rajvinder Singh , Gustavo Carneiro

Variational autoencoders (VAE) encode data into lower-dimensional latent vectors before decoding those vectors back to data. Once trained, one can hope to detect out-of-distribution (abnormal) latent vectors, but several issues arise when…

Machine Learning · Computer Science 2026-05-12 Alejandro Ascarate , Leo Lebrat , Rodrigo Santa Cruz , Clinton Fookes , Olivier Salvado

Unsupervised anomaly detection (UAD) has been widely implemented in industrial and medical applications, which reduces the cost of manual annotation and improves efficiency in disease diagnosis. Recently, deep auto-encoder with its variants…

Computer Vision and Pattern Recognition · Computer Science 2023-03-31 Mingqing Wang , Jiawei Li , Zhenyang Li , Chengxiao Luo , Bin Chen , Shu-Tao Xia , Zhi Wang

Visual surface anomaly detection aims to detect local image regions that significantly deviate from normal appearance. Recent surface anomaly detection methods rely on generative models to accurately reconstruct the normal areas and to fail…

Computer Vision and Pattern Recognition · Computer Science 2021-09-28 Vitjan Zavrtanik , Matej Kristan , Danijel Skočaj

Likelihood is a standard estimate for outlier detection. The specific role of the normalization constraint is to ensure that the out-of-distribution (OOD) regime has a small likelihood when samples are learned using maximum likelihood.…

Machine Learning · Computer Science 2023-06-16 Sangwoong Yoon , Yung-Kyun Noh , Frank Chongwoo Park