PreviewDiff puts a multimodal critic inside the denoising loop, beating Best-of-N at matched compute on SDXL and LTX-Video
PreviewDiff introduces a training-free test-time search method that decodes partial previews at selected denoising checkpoints, asks a multimodal judge to score and critique them, and uses the resulting natural-language feedback to branch over semantic prompt edits and locally re-noised latent continuations that are scored and selectively rolled forward, consistently outperforming budget-matched Best-of-N and scalar-search baselines on image and video generation benchmarks.