GANomaly: Semi-Supervised Anomaly Detection via Adversarial Training

Akcay, Samet; Atapour-Abarghouei, Amir; Breckon, Toby P.; Jawahar, C.V.; Li, Hongdong; Mori, Greg; Schindler, Konrad

Abstract

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 (abnormal). While this can be addressed as a supervised learning problem, a significantly more challenging problem is that of detecting the unknown/unseen anomaly case that takes us instead into the space of a one-class, semi-supervised learning paradigm. We introduce such a novel anomaly detection model, by using a conditional generative adversarial network that jointly learns the generation of high-dimensional image space and the inference of latent space. Employing encoder-decoder-encoder sub-networks in the generator network enables the model to map the input image to a lower dimension vector, which is then used to reconstruct the generated output image. The use of the additional encoder network maps this generated image to its latent representation. Minimizing the distance between these images and the latent vectors during training aids in learning the data distribution for the normal samples. As a result, a larger distance metric from this learned data distribution at inference time is indicative of an outlier from that distribution — an anomaly. Experimentation over several benchmark datasets, from varying domains, shows the model efficacy and superiority over previous state-of-the-art approaches.

Citation

Akcay, S., Atapour-Abarghouei, A., Breckon, T. P., Jawahar, C., Li, H., Mori, G., & Schindler, K. (2019). GANomaly: Semi-Supervised Anomaly Detection via Adversarial Training. In Computer Vision – ACCV 2018 : 14th Asian Conference on Computer Vision, Perth, Australia, December 2–6, 2018, Revised Selected Papers, Part III (622-637). https://doi.org/10.1007/978-3-030-20893-6_39

• Conference Name: 14th Asian Conference on Computer Vision (ACCV).
• Conference Location: Perth, Australia
• Start Date: Dec 2, 2018
• End Date: Dec 6, 2018
• Acceptance Date: Sep 18, 2018
• Online Publication Date: Dec 3, 2018
• Publication Date: 2019
• Deposit Date: Oct 8, 2018
• Publicly Available Date: Nov 15, 2018
• Pages: 622-637
• Series Title: Lecture notes in computer science
• Series Number: 11363
• Series ISSN: 0302-9743,1611-3349
• Book Title: Computer Vision – ACCV 2018 : 14th Asian Conference on Computer Vision, Perth, Australia, December 2–6, 2018, Revised Selected Papers, Part III.
• ISBN: 9783030208929
• DOI: https://doi.org/10.1007/978-3-030-20893-6_39
• Related Public URLs: https://arxiv.org/abs/1805.06725