Temporal Score Analysis for Understanding and Correcting Diffusion Artifacts

Figure 1. Why do diffusion models generate artifacts? We discover that a diffusion generative process necessarily undergoes three phases, we call them: (2) "Profiling" which recovers holistic mean templates, (2) "Mutation" which introduces local divergence, and (3) "Refinement" which rationalizes pixel-wise generation in spatial context. Four visual examples are shown: The first two rows are two examples of rational local mutations (in green boxes) either naturally integrated (Row 1) or reasonably eliminated (Row 2). The bottom two rows show two failure cases when mutations were trapped unreasonably (in red boxes), resisting refinement and resulting in artifacts. Phases are visualized in equal intervals for clarity; please zoom in for more details.