Luo Yixin, Yang Zhouwang
IEEE Trans Pattern Anal Mach Intell. 2024 Aug;46(8):5493-5503. doi: 10.1109/TPAMI.2024.3367532. Epub 2024 Jul 2.
Generative Adversarial Networks (GANs) are widely-used generative models for synthesizing complex and realistic data. However, mode collapse, where the diversity of generated samples is significantly lower than that of real samples, poses a major challenge for further applications. Our theoretical analysis demonstrates that the generator loss function is non-convex with respect to its parameters when there are multiple modes in real data. In particular, parameters that result in generated distributions with perfect partial mode coverage of the real distribution are the local minima of the generator loss function. To address mode collapse, we propose a unified framework called Dynamic GAN. This method detects collapsed samples in the generator by thresholding on observable discriminator outputs, divides the training set based on these collapsed samples, and trains a dynamic conditional model on the partitions. The theoretical outcome ensures progressive mode coverage and experiments on synthetic and real-world data sets demonstrate that our method surpasses several GAN variants. In conclusion, we examine the root cause of mode collapse and offer a novel approach to quantitatively detect and resolve it in GANs.
生成对抗网络(GANs)是用于合成复杂且逼真数据的广泛使用的生成模型。然而,模式坍塌,即生成样本的多样性显著低于真实样本的多样性,对进一步的应用构成了重大挑战。我们的理论分析表明,当真实数据存在多种模式时,生成器损失函数相对于其参数是非凸的。特别地,导致生成分布对真实分布具有完美部分模式覆盖的参数是生成器损失函数的局部最小值。为了解决模式坍塌问题,我们提出了一个名为动态GAN的统一框架。该方法通过对可观察到的判别器输出进行阈值处理来检测生成器中的坍塌样本,基于这些坍塌样本划分训练集,并在这些划分上训练动态条件模型。理论结果确保了渐进式模式覆盖,并且在合成数据集和真实世界数据集上的实验表明我们的方法优于几种GAN变体。总之,我们研究了模式坍塌的根本原因,并提供了一种在GAN中定量检测和解决它的新方法。