NiCI-Pruning: Enhancing Diffusion Model Pruning via Noise in Clean Image Guidance

The substantial successes achieved by diffusion probabilistic models have prompted the study of their employment in resource-limited scenarios. Pruning methods have been proven effective in compressing discriminative models relying on the correlation between training losses and model performances. However, diffusion models employ an iterative process for generating high-quality images, leading to a breakdown of such connections. To address this challenge, we propose a simple yet effective method, named NiCI-Pruning (Noise in Clean Image Pruning), for the compression of diffusion models. NiCI-Pruning capitalizes the noise predicted by the model based on clean image inputs, favoring it as a feature for establishing reconstruction losses. Accordingly, Taylor expansion is employed for the proposed reconstruction loss to evaluate the parameter importance effectively. Moreover, we propose an interval sampling strategy that incorporates a timestep-weighted schema, alleviating the risk of misleading information obtained at later timesteps. We provide comprehensive experimental results to affirm the superiority of our proposed approach. Notably, our method achieves a remarkable average reduction of 30.4% in FID score increase across five different datasets compared to the state-of-the-art diffusion pruning method at equivalent pruning rates. Our code and models have been made available at https://github.com/NUST-Machine-Intelligence-Laboratory/NiCI-Pruning.