通过混合类别对数空间数据,提升细粒度分布外检测的准确性。
Logit Mixture Outlier Exposure for Fine-grained Out-of-Distribution Detection
- 在对数空间中线性混合分布内与分布外数据,平滑类别间输出差异。
- 实验表明该方法显著减少决策边界附近的输出波动,提升检测稳定性。
- 特别适合需要精细区分相近分布外样本的场景,如高精度分类任务。
检测分布外数据的能力对于确保模型在未知或意外输入下的鲁棒性以及提升泛化性能至关重要。在多种分布外检测方法中,异常暴露(Outlier Exposure)和混合异常暴露(Mixture Outlier Exposure)是通过训练时引入异常数据来增强检测性能的有前景方案。然而,即使采用这些复杂技术,模型仍难以有效学习类别间关系,也难以清晰区分分布内与分布外数据的采样来源。为此,我们聚焦于对数空间——该空间中类别间分布特性明显区别于输入或特征空间。我们提出一种在对数空间中的线性插值技术,混合分布内与分布外数据,以促进类别间对数输出的平滑,并提升分布外检测性能,尤其适用于靠近分布内数据的分布外样本。同时,我们强制对数空间混合与输入空间混合所得对数结果保持一致性。实验表明,所提方法减少了决策边界附近模型输出的剧烈波动,实现更平滑、可靠的分布内/外分离。此外,我们在细粒度分布外检测任务上验证了该方法的有效性。
原文摘要 · Abstract (English)
The ability to detect out-of-distribution data is essential not only for ensuring robustness against unknown or unexpected input data but also for improving the generalization performance of the model. Among various out-of-distribution detection methods, Outlier Exposure and Mixture Outlier Exposure are promising approaches that enhance out-of-distribution detection performance by exposing the outlier data during training. However, even with these sophisticated techniques, it remains challenging for models to learn the relationships between classes effectively and to distinguish data sampling from in-distribution and out-of-distribution clearly. Therefore, we focus on the logit space, where the properties between class-wise distributions are distinctly separated from those in the input or feature spaces. Specifically, we propose a linear interpolation technique in the logit space that mixes in-distribution and out-of-distribution data to facilitate smoothing logits between classes and improve the out-of-distribution detection performance, particularly for out-of-distribution data that lie close to the in-distribution data. Additionally, we enforce consistency between the logits obtained through mixing in the logit space and those generated via mixing in the input space. Our experiments demonstrate that our logit-space mixing technique reduces the abrupt fluctuations in the model outputs near the decision boundaries, resulting in smoother and more reliable separation between in-distribution and out-of-distribution data. Furthermore, we evaluate the effectiveness of the proposed method on a fine-grained out-of-distribution detection task.
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