Enlarging the Capability of Diffusion Models for Inverse Problems by Guidance

The recent advent of diffusion models has led to significant progress in solving inverse problems, leveraging these models as effective generative priors. Nonetheless, challenges related to the ill-posed nature of such problems remain, such as 3D extension and overcoming inherent ambiguities in measurements. In this talk, we introduce strategies to address these issues. First, to enable 3D extension using only 2D diffusion models, we propose a novel approach using two perpendicular pre-trained 2D diffusion models which guides each solver to solve the 3D inverse problem. Specifically, by modelling the 3D data distribution as a product of 2D distributions sliced in different directions, our method effectively addresses the curse of dimensionality from the image guidance from the perpendicular direction. Second, drawing inspiration from the human ability to resolve visual ambiguities through perceptual biases, we introduce a novel latent diffusion inverse solver by incorporating guidance by text prompts. Specifically, our method applies the textual description of the preconception of the solution during the reverse sampling phase, of which description is dynamically reinforced through null-text optimization for adaptive negation. Our comprehensive experimental results show that our method successfully mitigates ambiguity in latent diffusion inverse solvers, enhancing their effectiveness and accuracy.