Diffusion Model Patching via Mixture-of-Prompts

We present Diffusion Model Patching (DMP), a simple method to boost the performance of pre-trained diffusion models that have already reached convergence, with a negligible increase in parameters. DMP inserts a small, learnable set of prompts into the model's input space while keeping the original model frozen. The effectiveness of DMP is not merely due to the addition of parameters but stems from its dynamic gating mechanism, which selects and combines a subset of learnable prompts at every step of the generative process (i.e., reverse denoising steps). This strategy, which we term "mixture-of-prompts'', enables the model to draw on the distinct expertise of each prompt, essentially "patching'' the model's functionality at every step with minimal yet specialized parameters. Uniquely, DMP enhances the model by further training on the original dataset already used for training, even in a scenario where significant improvements are typically not expected due to model convergence. Experiments show that DMP significantly enhances the converged FID of DiT-L/2 on FFHQ by 10.38%, achieved with only a 1.43% parameter increase and 50K additional training iterations.