Due to the scarcity of anomalies, deep anomaly detection models are typically trained in an unsupervised or semi-supervised manner, depending on the availability of a small number of labeled samples. Currently, most unsupervised approaches detect anomalies by identifying the deviant patterns from normal samples, and some semi-supervised studies also use labeled anomalies to improve performance. However, few studies have focused on how to take advantage of potential anomalies in an easily obtained and large-scale unlabeled dataset. Meanwhile, in a semi-supervised setting, although we assume there will be a small number of labeled anomalies, the task of anomaly classification is under-exploited, which is important for domain experts. In this work, we focus on the problem of anomaly detection and classification with limited labeled samples and a large number of unlabeled samples. To this end, we develop a few-shot anomaly detection and classification model based on reinforced data selection with a combinatorial reward, called FADScr. FADScr iteratively improves performance by exploring the unlabeled dataset and selects informative samples to augment the training set to enhance both anomaly detection and classification. Experimental results show that our proposed framework is able to improve the performance of anomaly detection and classification with only a few labeled samples initially.
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VideoSSL: Semi-Supervised Learning for Video Classification
We propose a semi-supervised learning approach for video classification, VideoSSL, using convolutional neural networks (CNN). Like other computer vision tasks, existing supervised video classification methods demand a large amount of labeled data to attain good performance. However, annotation of a large dataset is expensive and time consuming. To minimize the dependence on a large annotated dataset, our proposed semi-supervised method trains from a small number of labeled examples and exploits two regulatory signals from unlabeled data. The first signal is the pseudo-labels of unlabeled examples computed from the confidences of the CNN being trained. The other is the normalized probabilities, as predicted by an image classifier CNN, that captures the information about appearances of the interesting objects in the video. We show that, under the supervision of these guiding signals from unlabeled examples, a video classification CNN can achieve impressive performances utilizing a small fraction of annotated examples on three publicly available datasets: UCF101, HMDB51, and Kinetics.
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- Award ID(s):
- 2041307
- PAR ID:
- 10279258
- Date Published:
- Journal Name:
- Winter Conference on Applications of Computer Vision (WACV), 2021.
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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