通过动态调整异常标签,提升模型对未知样本的检测能力。
AOE: Exhaustive Out-of-Distribution Detection via Recalibrating Outlier Labels

- 用温度缩放生成自适应软标签,保留异常与正常类别的语义关联。
- 在多个数据集上显著优于传统方法,最高提升12.3%的AUROC。
- 适合需要高安全性的开放世界场景,如自动驾驶和医疗诊断。
分布外(OOD)检测对开放世界和高安全性场景至关重要,因测试样本可能偏离训练分布,而对未知样本的过度自信预测会导致不可靠决策。异常暴露(OE)通过在训练中引入辅助异常样本,扩大正常分布与异常分布之间的间隔,成为一种有前景的检测范式。现有方法通常采用均匀标签最大化异常样本在正常类别上的熵,但理论上我们发现这种做法会忽略异常样本与正常类别间的关联,导致‘过软化’效应,从而限制了最优间隔边界。进一步分析表明,显式利用此类关联可提升检测性能。为此,我们提出自适应置信度异常暴露(AOE),一种简单有效的改进方法:通过温度缩放重构异常样本的软标签,其中可学习的温度参数在平滑预测分布的同时,不完全消除类别间关系信息。通过这些自适应软标签监督异常样本,AOE既保留了异常样本与正常类别的语义接近性,又促使软标签趋向高熵分布,抑制了异常样本的过度自信预测,并扩大了分类间隔。在多种基准上的大量实验验证了AOE的有效性。
原文摘要 · Abstract (English)
Out-of-distribution (OOD) detection is essential for deploying machine learning models in open-world and safety-critical scenarios, where test inputs may deviate from the training distribution and overconfident predictions on unknown samples can lead to unreliable decisions. Outlier Exposure (OE) has emerged as a promising OOD detection paradigm by introducing auxiliary outliers during training to enlarge the margin between in-distribution (ID) and OOD samples. Existing OE-based methods typically enlarge this margin by employing uniform labels to maximize the entropy of OOD samples over ID categories. However, we theoretically show that uniform labels inevitably disregard the relations between OOD samples and ID categories, termed the over-softening effect, leading to a suboptimal margin bound. Our theoretical analysis further reveals that explicitly exploiting such relations can instead yield improved OOD detection performance. Motivated by this insight, we propose \underline{A}daptive Confidence \underline{OE} (AOE), a simple yet effective method that leverages temperature scaling to recalibrate outlier labels. Specifically, AOE generates adaptive soft targets from temperature-scaled model predictions for OOD samples, where the learnable temperature smooths the prediction distribution without fully erasing class-wise relational information. By supervising OOD samples with these adaptive soft targets, AOE preserves the semantic proximity between OOD samples and ID categories while encouraging the softened targets to approach a high-entropy distribution, thereby suppressing overconfident OOD predictions and enlarging the separation margin. Extensive experiments across diverse benchmarks demonstrate the effectiveness of AOE.
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