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 flow-based model



A Appendix

Neural Information Processing Systems

In the following subsections, we provide theoretical derivations. In this subsection, we provide a formal description of the consistency property of score matching. Assumption A.4. (Compactness) The parameter space is compact. Assumption A.5. (Identifiability) There exists a set of parameters A.3 are the conditions that ensure A.7 lead to the uniform convergence property [ In the following Lemma A.9 and Proposition A.10, we examine the sufficient condition for We show that the sufficient conditions stated in Lemma A.9 can be satisfied using the Figure A1: An illustration of the relationship between the variables discussed in Proposition 4.1, Lemma A.12, and Lemma A.13. The properties of KL divergence and Fisher divergence presented in the last two rows are derived in Lemmas A.12 In this section, we provide formal derivations for Proposition 4.1, Lemma A.12, and Lemma A.13. Based on Remark A.14, the following holds: D In this section, we elaborate on the experimental setups and provide the detailed configurations for the experiments presented in Section 5 of the main manuscript.








SoftFlow: Probabilistic Framework for Normalizing Flow on Manifolds

Neural Information Processing Systems

Flow-based generative models are composed of invertible transformations between two random variables of the same dimension. Therefore, flow-based models cannot be adequately trained if the dimension of the data distribution does not match that of the underlying target distribution. In this paper, we propose SoftFlow, a probabilistic framework for training normalizing flows on manifolds. To sidestep the dimension mismatch problem, SoftFlow estimates a conditional distribution of the perturbed input data instead of learning the data distribution directly. We experimentally show that SoftFlow can capture the innate structure of the manifold data and generate high-quality samples unlike the conventional flow-based models. Furthermore, we apply the proposed framework to 3D point clouds to alleviate the difficulty of forming thin structures for flow-based models. The proposed model for 3D point clouds, namely SoftPointFlow, can estimate the distribution of various shapes more accurately and achieves state-of-the-art performance in point cloud generation.


FlowTurbo: Towards Real-time Flow-Based Image Generation with Velocity Refiner

Neural Information Processing Systems

Building on the success of diffusion models in visual generation, flow-based models reemerge as another prominent family of generative models that have achieved competitive or better performance in terms of both visual quality and inference speed. By learning the velocity field through flow-matching, flow-based models tend to produce a straighter sampling trajectory, which is advantageous during the sampling process. However, unlike diffusion models for which fast samplers are well-developed, efficient sampling of flow-based generative models has been rarely explored. In this paper, we propose a framework called FlowTurbo to accelerate the sampling of flow-based models while still enhancing the sampling quality. Our primary observation is that the velocity predictor's outputs in the flow-based models will become stable during the sampling, enabling the estimation of velocity via a lightweight velocity refiner. Additionally, we introduce several techniques including a pseudo corrector and sample-aware compilation to further reduce inference time. Since FlowTurbo does not change the multi-step sampling paradigm, it can be effectively applied for various tasks such as image editing, inpainting, etc.