Mitigating the reconstruction-detection trade-off in VAE-based unsupervised anomaly detection

Fuente: arXiv
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Autores principales: Senellart, Agathe, Solal, Maëlys, Allassonnière, Stéphanie, Burgos, Ninon
Formato: Preprint
Publicado: 2026
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author Senellart, Agathe
Solal, Maëlys
Allassonnière, Stéphanie
Burgos, Ninon
author_facet Senellart, Agathe
Solal, Maëlys
Allassonnière, Stéphanie
Burgos, Ninon
contents Variational autoencoders are widely used for unsupervised anomaly detection. Model selection however remains an open-question: to remain fully unsupervised, hyperparameters are often chosen to minimize the reconstruction error on normal samples. In this paper, we reveal a trade-off between reconstruction quality and anomaly detection among $β$-VAE models. Models with constrained latent space reach higher detection metrics but lower reconstruction quality. We also assess the performance variability across random seeds and show it is linked to the distance between normal and abnormal latent distributions. From this analysis, we justify and investigate two methods to mitigate the reconstructiondetection tradeoff: beta-scheduling and the Sparse VAE. The latter especially shows an improvement in detection while maintaining high reconstruction quality.
format Preprint
id arxiv_https___arxiv_org_abs_2605_02918
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Mitigating the reconstruction-detection trade-off in VAE-based unsupervised anomaly detection
Senellart, Agathe
Solal, Maëlys
Allassonnière, Stéphanie
Burgos, Ninon
Machine Learning
Artificial Intelligence
Variational autoencoders are widely used for unsupervised anomaly detection. Model selection however remains an open-question: to remain fully unsupervised, hyperparameters are often chosen to minimize the reconstruction error on normal samples. In this paper, we reveal a trade-off between reconstruction quality and anomaly detection among $β$-VAE models. Models with constrained latent space reach higher detection metrics but lower reconstruction quality. We also assess the performance variability across random seeds and show it is linked to the distance between normal and abnormal latent distributions. From this analysis, we justify and investigate two methods to mitigate the reconstructiondetection tradeoff: beta-scheduling and the Sparse VAE. The latter especially shows an improvement in detection while maintaining high reconstruction quality.
title Mitigating the reconstruction-detection trade-off in VAE-based unsupervised anomaly detection
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.02918