解决不平衡域适应中标签偏移问题,提升伪标签可靠性。
Contrastive Conditional Alignment based on Label Shift Calibration for Imbalanced Domain Adaptation
- 通过对比条件对齐缓解协变量偏移,增强特征不变性与判别力。
- 基于标签偏移度量校准目标域预测,使伪标签更贴近真实分布。
- 适合处理源域与目标域存在标签分布差异的场景。
现有无监督域适应方法多关注协变量偏移,难以应对同时存在协变量偏移与标签偏移的不平衡域适应(IDA)问题。虽有基于目标域伪标签的自训练方法取得进展,但在IDA场景下,源域分类器在目标域会产生不同决策偏差,导致伪标签不可靠并引发错误累积。为此,我们提出基于标签偏移校准的对比条件对齐(CCA-LSC)方法,同时应对两类偏移。首先,通过对抗学习、加权移动中心对齐和判别特征对齐,实现领域不变且类可分的表示学习;其次,估计目标域概率分布,并基于标签偏移度量校准目标样本预测,促进伪标签与真实目标数据分布一致。大量实验表明,该方法在同时存在标签偏移与协变量偏移的基准上优于现有UDA与IDA方法。
原文摘要 · Abstract (English)
Many existing unsupervised domain adaptation (UDA) methods primarily focus on covariate shift, limiting their effectiveness in imbalanced domain adaptation (IDA) where both covariate shift and label shift coexist. Recent IDA methods have achieved promising results based on self-training using target pseudo labels. However, under the IDA scenarios, the classifier learned in the source domain will exhibit different decision bias from the target domain. It will potentially make target pseudo labels unreliable, and will further lead to error accumulation with incorrect class alignment. Thus, we propose contrastive conditional alignment based on label shift calibration (CCA-LSC) for IDA, to address both covariate shift and label shift. Initially, our contrastive conditional alignment resolve covariate shift to learn representations with domain invariance and class discriminability, which include domain adversarial learning, sample-weighted moving average centroid alignment and discriminative feature alignment. Subsequently, we estimate the probability distribution of the target domain, and calibrate target sample classification predictions based on label shift metrics to encourage labeling pseudo-labels more consistently with the distribution of real target data. Extensive experiments are conducted and demonstrate that our method outperforms existing UDA and IDA methods on benchmarks with both label shift and covariate shift. Our code is available at https://github.com/ysxcj-hub/CCA-LSC.
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