Generative Modeling with Flow-Guided Density Ratio Learning, Alvin Heng★, Abdul Fatir Ansari★, and Harold Soh★, arXiv preprint, 2023
Links: Paper | Github

We present Flow-Guided Density Ratio Learning (FDRL), a simple and scalable approach to generative modeling which builds on the stale (time-independent) approximation of the gradient flow of entropy-regularized f-divergences introduced in DGflow. In DGflow, the intractable time-dependent density ratio is approximated by a stale estimator given by a GAN discriminator. This is sufficient in the case of sample refinement, where the source and target distributions of the flow are close to each other. However, this assumption is invalid for generation and a naive application of the stale estimator fails due to the large chasm between the two distributions.

FDRL proposes to train a density ratio estimator such that it learns from progressively improving samples during the training process. We show that this simple method alleviates the density chasm problem, allowing FDRL to generate images of dimensions as high as 128×128, as well as outperform existing gradient flow baselines on quantitative benchmarks. We also show the flexibility of FDRL with two use cases. First, unconditional FDRL can be easily composed with external classifiers to perform class-conditional generation. Second, FDRL can be directly applied to unpaired image-to-image translation with no modifications needed to the framework.


You can find our paper here. Check out our repository here on github.


Please consider citing our paper if you build upon our results and ideas.

Alvin Heng★, Abdul Fatir Ansari★, and Harold Soh★, “Generative Modeling with Flow-Guided Density Ratio Learning”, arXiv preprint, 2023

title={Generative Modeling with Flow-Guided Density Ratio Learning},
author={Heng, Alvin and Fatir Ansari, Abdul and Soh, Harold},
journal={arXiv e-prints},


If you have questions or comments, please contact Alvin or Harold.


Written by

Alvin Heng

Physicist in my past life, generative modeling in my current!