NTM enables fast image generation (4 steps) while preserving exact likelihood calculation—something previous fast diffusion methods couldn't do—by using normalizing flows for each denoising step instead of simple Gaussian assumptions.
This paper introduces Normalizing Trajectory Models (NTM), a new approach for fast image generation that compresses diffusion sampling from many steps to just four. Unlike existing fast methods that lose the ability to calculate exact probabilities, NTM maintains a mathematically exact likelihood while generating high-quality images, making it useful for both generation and evaluation.