用贝叶斯最优判别误差率优化GAN,提升生成质量与训练稳定性。
Revisiting GAN with Bayes-Optimal Discrimination
- 以贝叶斯最优阈值损失直接优化判别误差率,替代传统交叉熵。
- 在平衡先验下,最大化代理误差率可最小化数据与生成分布的总变差。
- 适用于追求稳定训练和高质量生成的图像生成任务研究者。
我们提出一种替代标准GAN训练的方法:不使用交叉熵训练判别器区分真实样本与生成样本,而是直接针对判别贝叶斯误差率(BER)进行优化。为此,我们采用近期提出的贝叶斯最优学习阈值(BOLT)损失,并训练生成器以最大化判别BER的代理目标。这一视角为GAN训练提供了统一理解:不同目标可被解释为对判别BER的参数化上界,体现平滑性与紧致性的权衡。在类先验平衡条件下,使用无约束判别器最大化代理BER,可使数据分布与生成分布间的总变差最小化;若将判别器限制为1-利普希茨连续,则该最大化目标定义的差异上界为Wasserstein-1距离,从而与Wasserstein GAN建立联系。在多个图像生成数据集上,采用匹配架构与优化设置的实验表明,基于代理BER的GAN训练相比标准基线,在样本质量和覆盖度方面均有提升。分析表明,所提出的贝叶斯视角能在训练稳定性和生成器收敛至真实数据分布之间实现更优平衡。
原文摘要 · Abstract (English)
We propose an alternative to the standard GAN training approach, in which the discriminator is a binary classifier trained by cross-entropy to distinguish real samples from generated ones. Instead, we directly target the discrimination Bayes error rate (BER). To this end, we use the recently proposed Bayes optimal learning threshold (BOLT) loss and train the generator to maximize a surrogate of the discrimination BER. This viewpoint gives a unified perspective on GAN training: different objectives can be interpreted as parameterized bounds on the discrimination BER that describe a trade-off between smoothness and tightness. We show that, under balanced class priors, maximizing the surrogate BER with an unconstrained discriminator minimizes the total variation between the data and generator distributions. By constraining the discriminator to be $1$-Lipschitz, the proposed maximization objective defines a discrepancy that is upper-bounded by the Wasserstein-1 distance, thereby linking it to Wasserstein GAN. Experiments on several image-generation datasets under matched architectures and optimization settings show that GAN training using the surrogate BER improves sample quality and coverage over standard baselines. This analysis suggests that the proposed Bayesian viewpoint can achieve a better trade-off between training stability and convergence of the generator to the data distribution.
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