Top-k Training of GANs: Improving GAN Performance by Throwing Away Bad Samples

We introduce a simple (one line of code) modification to the Generative Adversarial Network (GAN) training algorithm that materially improves results with no increase in computational cost: When updating the generator parameters, we simply zero out the gradient contributions from the elements of the batch that the critic scores as 'least realistic'. Through experiments on many different GAN variants, we show that this 'top-k update' procedure is a generally applicable improvement. In order to understand the nature of the improvement, we conduct extensive analysis on a simple mixture-of-Gaussians dataset and discover several interesting phenomena. Among these is that, when gradient updates are computed using the worst-scoring batch elements, samples can actually be pushed further away from their nearest mode. We also apply our method to recent GAN variants and improve state-of-theart FID for conditional generation from 9.21 to 8.57 on CIFAR-10. ⇤ Samarth Sinha and Zhengli Zhao contributed equally as joint first authors.