Papers › FlowCon: Out-of-Distribution Detection using Flow-Based Contrastive Learning

FlowCon: Out-of-Distribution Detection using Flow-Based Contrastive Learning

3 Jul 2024arXiv:2407.03489archive 2025-07-28

Saandeep Aathreya, Shaun Canavan

Identifying Out-of-distribution (OOD) data is becoming increasingly critical as the real-world applications of deep learning methods expand. Post-hoc methods modify softmax scores fine-tuned on outlier data or leverage intermediate feature layers to identify distinctive patterns between In-Distribution (ID) and OOD samples. Other methods focus on employing diverse OOD samples to learn discrepancies between ID and OOD. These techniques, however, are typically dependent on the quality of the outlier samples assumed. Density-based methods explicitly model class-conditioned distributions but this requires long training time or retraining the classifier. To tackle these issues, we introduce \textit{FlowCon}, a new density-based OOD detection technique. Our main innovation lies in efficiently combining the properties of normalizing flow with supervised contrastive learning, ensuring robust representation learning with tractable density estimation. Empirical evaluation shows the enhanced performance of our method across common vision datasets such as CIFAR-10 and CIFAR-100 pretrained on ResNet18 and WideResNet classifiers. We also perform quantitative analysis using likelihood plots and qualitative visualization using UMAP embeddings and demonstrate the robustness of the proposed method under various OOD contexts. Code will be open-sourced post decision.

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Tasks

Contrastive LearningDensity EstimationOut-of-Distribution DetectionRepresentation Learning

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Methods

Average PoolingBatch NormalizationConvolutionDropoutFocusGlobal Average PoolingKaiming InitializationReLUResidual ConnectionSoftmaxWide Residual BlockWideResNet

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