Correcting Diffusion Generation through Resampling
Authors: Yujian Liu, Yang Zhang, Tommi Jaakkola, Shiyu Chang

Despite diffusion models' superior capabilities in modeling complex distributions there are still non-trivial distributional discrepancies between generated and ground-truth images which has resulted in several notable problems in image generation including missing object errors in text-to-image generation and low image quality. Existing methods that attempt to address these problems mostly do not tend to address the fundamental cause behind these problems which is the distributional discrepancies and hence achieve sub-optimal results. In this paper we propose a particle filtering framework that can effectively address both problems by explicitly reducing the distributional discrepancies. Specifically our method relies on a set of external guidance including a small set of real images and a pre-trained object detector to gauge the distribution gap and then design the resampling weight accordingly to correct the gap. Experiments show that our methods can effectively correct missing object errors and improve image quality in various image generation tasks. Notably our method outperforms the existing strongest baseline by 5% in object occurrence and 1.0 in FID on MS-COCO. Our code is available at https://github.com/UCSB-NLP-Chang/diffusion_resampling.git.