通过匹配教师模型的类别相关性,提升知识蒸馏效果。
Efficient and Robust Knowledge Distillation from A Stronger Teacher Based on Correlation Matching
- 用皮尔逊与斯皮尔曼相关系数联合设计蒸馏损失,匹配教师输出的类别相对顺序。
- 在CIFAR-100和ImageNet上均达到当前最优性能,且对强教师模型更有效。
- 动态调整损失权重,适配难易样本,适合各类教师架构与蒸馏方法。
知识蒸馏(KD)已成为神经网络压缩与性能提升的关键技术。现有大多数方法基于KL散度,从复杂教师模型向轻量学生模型转移‘暗知识’,但其性能提升呈现边际递减现象:更强的教师模型未必带来成比例的学生模型增强。本文发现,基于KL的蒸馏会隐式改变学生模型学习到的类间关系,导致决策边界更复杂模糊,降低准确率与泛化能力。因此,提出一种新的相关性匹配知识蒸馏(CMKD)方法,不仅传递教师输出的概率值,还保留类别间的相对排序关系,结合皮尔逊与斯皮尔曼相关系数设计蒸馏损失,并根据样本难度动态调整两类损失权重。实验表明,该方法在CIFAR-100与ImageNet上均表现优异,可稳定超越现有方法,且适用于多种教师架构、规模及其它蒸馏策略。
原文摘要 · Abstract (English)
Knowledge Distillation (KD) has emerged as a pivotal technique for neural network compression and performance enhancement. Most KD methods aim to transfer dark knowledge from a cumbersome teacher model to a lightweight student model based on Kullback-Leibler (KL) divergence loss. However, the student performance improvements achieved through KD exhibit diminishing marginal returns, where a stronger teacher model does not necessarily lead to a proportionally stronger student model. To address this issue, we empirically find that the KL-based KD method may implicitly change the inter-class relationships learned by the student model, resulting in a more complex and ambiguous decision boundary, which in turn reduces the model's accuracy and generalization ability. Therefore, this study argues that the student model should learn not only the probability values from the teacher's output but also the relative ranking of classes, and proposes a novel Correlation Matching Knowledge Distillation (CMKD) method that combines the Pearson and Spearman correlation coefficients-based KD loss to achieve more efficient and robust distillation from a stronger teacher model. Moreover, considering that samples vary in difficulty, CMKD dynamically adjusts the weights of the Pearson-based loss and Spearman-based loss. CMKD is simple yet practical, and extensive experiments demonstrate that it can consistently achieve state-of-the-art performance on CIRAR-100 and ImageNet, and adapts well to various teacher architectures, sizes, and other KD methods.
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