NeurIPS 2026 论文列表

Conference on Neural Information Processing Systems

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6,437篇论文

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GeoSPRINT: Geometric Redundancy-Aware Step Pruning for Inference in Diffusion Trajectories

Arpita Joshi

展开摘要

Diffusion models achieve high sample quality but remain expensive at inference time because sampling requires many sequential neural function evaluations (NFEs). Existing acceleration methods either use fixed step-skipping schedules, adapt step sizes based on local numerical error, or require additional training. We introduce GeoSPRINT (Geometric Step Pruning for Inference in Trajectories), a training-free framework for constructing non-uniform sampling schedules from the geometry of denoising trajectories. GeoSPRINT detects geometrically redundant steps using a hyperplanarity test in latent space, implemented efficiently via QR factorization, and converts the resulting redundancy profile into a sampling schedule that allocates more steps to high-curvature regions of the trajectory. In addition, we introduce the trajectory projection score $\alpha_{\mathrm{traj}}$, a residual-variance metric that quantifies trajectory straightness and serves as a model-free diagnostic for rectified flow quality. Across CIFAR-10 ($32{\times}32$), LSUN Church ($256{\times}256$), and Stable Diffusion v1.5 ($512{\times}512$ latent), GeoSPRINT consistently improves over uniform DDIM (Denoising Diffusion Implicit Models) schedules at matched NFE budgets. On CIFAR-10, GeoSPRINT improves FID (Fréchet Inception Distance) by 0.7-1.1 over DDIM across 49-89 NFEs and surpasses DPM-Solver++ at NFE${\geq}30$ despite using a first-order DDIM solver. On LSUN Church, it reduces FID from 1.48 to 1.26 at 52 steps, and on Stable Diffusion v1.5 it achieves up to 1.93 FID improvement over DDIM. These results show that trajectory geometry provides a useful global signal for allocating inference steps and that schedule quality can substantially improve diffusion sampling efficiency without retraining.

Poster
GeoMemory: Geometry-Indexed Memory for Long-Horizon Interactive Video Generation

Junchao Huang, Xinting Hu, Boyao Han, Shaoshuai Shi, Zhuotao Tian, Tianyu He, Li Jiang

展开摘要

Autoregressive video diffusion models have demonstrated effectiveness in interactive game generation, with Minecraft gameplay serving as a representative application. To faithfully simulate gameplay, a model must generate natural content when exploring new scenes while preserving spatial consistency when revisiting explored areas. Under limited computation budgets, it must compress and exploit historical cues within a finite context window, which exposes a trade-off: models relying solely on temporal context offer flexible exploration but suffer from poor revisit consistency, whereas adding spatial memory strengthens consistency but may degrade new scene generation quality when the model over-relies on sparse or unreliable spatial context. We present GeoMemory, a learning framework that pairs training protocols with a geometry-indexed spatial memory. Specifically, our Hybrid Training exposes the model to both exploration and revisitation regimes, guiding the model to rely on temporal memory in new scenes while effectively incorporating spatial memory upon revisits. Chained Forward Training creates larger pose variations and encourages reliance on spatial memory for maintaining consistency. For spatial memory, we integrate Point-to-Frame Retrieval with an incremental 3D cache generated by VGGT, enabling constant-time retrieval of relevant historical context regardless of sequence length. Extensive experiments demonstrate that GeoMemory achieves superior performance in both long-term spatial consistency and visual quality in new scenes with real-time interaction.

Poster
Generative Modeling via Drifting

Mingyang Deng, He Li, Tianhong Li, Yilun Du, Kaiming He

展开摘要

Generative modeling can be formulated as learning a mapping $f$ such that its pushforward distribution matches the data distribution. The pushforward behavior can be carried out iteratively at inference time, for example, in diffusion/flow-based models. In this paper, we propose *Drifting Models*, a generative modeling framework that evolves the pushforward distribution during training and naturally admits one-step inference. We introduce a drifting field that governs the sample movement and achieves equilibrium when the distributions match. This leads to a training objective that allows the neural network optimizer to evolve the distribution. In experiments, our one-step generator achieves state-of-the-art results on ImageNet 256$\times$256, with FID 1.54 in latent space and 1.61 in pixel space. We hope that our work opens up new opportunities for high-quality one-step generation.

Oral
Generative Modeling under Non-Monotone MAR Missingness via Approximate Wasserstein Gradient Flows

Gitte Kremling, Jeffrey Näf, Johannes Lederer

展开摘要

The prevalence of missing values in data science poses a substantial risk to any further analyses. Despite a wealth of research, principled nonparametric methods to deal with general non-monotone missingness are still scarce. Instead, ad-hoc imputation methods are often used, for which it remains unclear whether the correct distribution can be recovered. In this paper, we propose FLOWGEM, a principled iterative method for generating a complete dataset from a dataset with values Missing at Random (MAR). Motivated by convergence results of the ignoring maximum likelihood estimator, our approach minimizes the expected Kullback-Leibler (KL) divergence between the observed data distribution and the distribution of the generated sample over different missingness patterns. To minimize the KL divergence, we employ a discretized particle evolution of the corresponding Wasserstein Gradient Flow, where the velocity field is approximated using a local linear estimator of the density ratio. This construction yields a data generation scheme that iteratively transports an initial particle ensemble toward the target distribution. Simulation studies and real-data benchmarks demonstrate that FLOWGEM achieves state-of-the-art performance across a range of settings, including the challenging case of non-monotone MAR mechanisms. Together, these results position FLOWGEM as a principled and practical alternative to existing imputation methods, and a decisive step towards closing the gap between theoretical rigor and empirical performance.

Poster
Generative Control as Optimization: Time Unconditional Flow Matching for Adaptive and Robust Robotic Control

Zunzhe Zhang, Runhan Huang, Yicheng Liu, Shaoting Zhu, Linzhan Mou, Hang Zhao

展开摘要

Diffusion and flow-based generators are increasingly used in robot policies to produce action chunks from visual observations, proprioception, and language instructions. However, closed-loop robot control requires solving action-generation problems of varying difficulty, whereas standard diffusion and flow-matching inference typically follows a fixed integration schedule. We introduce **Generative Control as Optimization (GeCO)**, a time-unconditional framework that turns action synthesis from fixed-time integration into iterative optimization. GeCO learns a stationary velocity field over action sequences, and refines actions until the field norm becomes small. This enables adaptive computation at each planning call: simple states can terminate early, while difficult states can use additional refinement. The same field norm also provides a lightweight signal for non-convergent action generation under distribution shift. GeCO can be instantiated in both diffusion-transformer policies and flow-matching Vision-Language-Action (VLA) systems without changing the surrounding policy interface. Across simulation benchmarks and real-world tasks, GeCO matches or improves task performance while enabling convergence-based inference as a plug-and-play replacement for standard time-conditioned action generators.

Poster
Generative Actor-Critic with Soft Bridge Policies

Ke He, Le He, Shunpu Tang, Yafei Wang, Lisheng Fan

展开摘要

Expressive generative policies such as diffusion and flow models are appealing for maximum-entropy (MaxEnt) online reinforcement learning because of their ability to model multimodal and highly non-Gaussian action distributions. However, training effective soft generative policies faces two obstacles that often arise together. First, marginal action densities are often unavailable, so existing methods typically rely on entropy bounds, heuristic proxies or approximations. Second, iterative shared-parameter samplers raise inference cost and require backpropagation through time over repeated network evaluations, increasing memory cost and destabilizing policy optimization. These obstacles motivate us to seek a generative policy that exposes a tractable MaxEnt objective while requiring only a single sampled actor forward pass for action generation. To this end, we propose soft generative actor-critic (SoftGAC), whose actor defines a stochastic bridge from a fixed base latent to a terminal action latent in pre-tanh space. This structured bridge allows us to lift the MaxEnt objective as an analytically tractable path-wise relative-entropy objective against a high-entropy reference process. In practical finite-step implementation, this relative entropy reduces exactly to sampled transition control energy and thus provides principled soft regularization. Moreover, we keep the single-pass actor lightweight by using small step-specific bridge transitions, each evaluated only once per sampled action, while maintaining a parameter budget comparable to strong actor baselines. Extensive experiments on challenging continuous-control benchmarks show that \myalgo attains higher or competitive returns than strong generative policy baselines, including diffusion and flow-matching policies, while staying in the low-latency regime of one-pass actors and avoiding the much higher cost of many-step diffusion samplers, showing considerable improvements in the compute-return tradeoff.

Poster
Generative Active Learning via Bayesian Acquisition for Improving the Efficiency of Synthetic Data

Jeongjun Lee, Gyeonghoon Ko, Juho Lee

展开摘要

Unlike real-world datasets, utilizing synthetic data from generative models as train dataset necessitates a rigorous consideration of the training data's informativeness. In this paper, we propose a novel framework designed to steer diffusion models based on Bayesian epistemic uncertainty to train the target model. To ensure computational tractability, we estimate the Bayesian Active Learning by Disagreement (BALD) score by applying the Laplace approximation specifically to the last-layer parameters of the downstream model. Furthermore, we incorporate Feynman-Kac Steering (FKS) for diffusion to enhance the structural diversity of the synthetic samples and mitigate the emergence of undesirable artifacts. Extensive experiments on Imagenette and ImageNet-100 for the classification task and MS-COCO for the object detection task demonstrate that our method significantly outperforms existing baselines in downstream accuracy and OOD generalization. Furthermore, our analysis of pairwise distances between inter-class and intra-class confirms that our method effectively expands the downstream model's knowledge manifold by generating diverse and informative training signals.

Poster
Generating Physically Consistent Molecules with Energy-Based Models

Christoph Griesbacher, Lea Bogensperger, Andreas Habring, Thomas Pock

展开摘要

Molecules in equilibrium follow a Boltzmann distribution, making the underlying energy landscape a physically grounded modeling objective. However, such landscapes are difficult to learn from data and, once learned, hard to sample from. Diffusion and flow-matching models sidestep these difficulties by learning a time-conditional score or transport field between noise and data, losing the energy inductive bias in exchange for a more tractable training objective. We introduce EBMol, an energy-based model (EBM) that restores this inductive bias by learning an atom-additive scalar potential without explicit simulation during training. Our method employs a flow-inspired Restoring Field Matching objective to approximate the energy landscape. We adopt the Mirror-Langevin algorithm for sampling, enabling unified updates of atomic positions and types, and incorporate parallel tempering for inference-time compute scaling. EBMol is the first EBM for 3D molecular generation to achieve state-of-the-art performance on QM9 and GEOM-Drugs. Moreover, we show that the learned energy landscape serves as a principled quality metric for ranking and filtering configurations, and demonstrate controllable generation without retraining through shape-steered sampling via potential composition and zero-shot linker design.

Spotlight
Generating Financial Time Series by Matching Random Convolutional Features

Konrad Mueller, Nikita Zozoulenko, Ben Wood, Thomas Cass, Lukas Gonon

展开摘要

Generating realistic financial time series is challenging as training data is often limited to a single historical path. With such scarce data, overfitting is hard to avoid, especially under adversarial training where a trained discriminator can memorize the training samples. To mitigate this, recent approaches train generators to minimize the discrepancy between untrained feature representations of real and generated time series. In these works, the feature maps are based on path signatures, which can fail to capture relevant time series properties at tractable truncation depths. In this work, we instead train generators by matching random convolutional features of real and generated time series. Existing random convolutional feature maps, such as Rocket and Hydra, have been shown to provide informative representations of real-world time series, but cannot supervise generative models because they are non-differentiable. We introduce **SOCK** (***SO**ft **C**ompeting **K**ernels*), a fully differentiable random convolutional feature map, suited to train generative time series models. We show that generators trained by matching random SOCK features consistently outperform signature and diffusion baselines across a wide range of small-sample financial datasets. We further demonstrate SOCK's expressiveness on two-sample hypothesis testing and time series classification tasks, where SOCK matches or outperforms existing unsupervised feature maps.

Poster
Generalized Wasserstein Flow Matching: Transport Plans, Everywhere, All at Once

Moritz Piening, Richard Duong, Gabriele Steidl

展开摘要

Flow matching has recently emerged as a flexible and efficient framework for generative modelling by learning deterministic transport dynamics between probability measures. In this work, we extend flow matching to the space of probability measures over probability measures, introducing a Wasserstein-on-Wasserstein (WoW) formulation. Leveraging the nested Wasserstein geometry, we show that measures over transport plans naturally induce velocity fields that realize metameasure flows. This yields a principled generalization of Wasserstein flow matching via coupled outer and inner transport plans. To address the substantial computational cost of WoW transport, we propose scalable approximations based on sliced and linear Wasserstein distances, enabling efficient training while promoting numerically stable, near-straight trajectories. Our framework unifies and extends existing approaches to point cloud and set generation, providing a practical and theoretically grounded method for generative modelling in WoW spaces.

Poster
Generalization Dynamics of Linear Diffusion Models

Claudia Lioba Merger, Sebastian Goldt

展开摘要

Diffusion models are powerful generative models that produce high-quality samples from complex data. While their infinite-data behavior is well understood, their generalization with finite data remains less clear. Classical learning theory predicts that generalization occurs at a sample complexity that is exponential in the dimension, far exceeding practical needs. We address this gap by analyzing diffusion models through the lens of data covariance spectra, which often follow power-law decays, reflecting the structure of real data. To understand whether such a power-law structure can benefit learning in diffusion models, we develop a theoretical framework based on linear neural networks, congruent with a Gaussian hypothesis on the data. We quantify how the covariance spectra of data and regularization impact generalization. We find two regimes: When $N <d$, not all directions of variation are present in the training data, which results in a large gap between training and test loss. In this regime, we demonstrate how a power-law data structure, as well as regularization and early stopping help to prevent overfitting. For $N \gg d$, we find that the sampling distributions of linear diffusion models approach their optimum (measured by the Kullback-Leibler divergence) linearly with $d/N$, independent of the specifics of the data distribution. Our work clarifies how sample complexity governs generalization in a simple model of diffusion-based generative models.

Poster
GenRec: Knowing Where to Reconstruct and Where to Generate

Ata Çelen, Jaewoo Jung, Federico Tombari, Marc Pollefeys, Sunghwan Hong, Michael Niemeyer, Daniel Barath

展开摘要

Generative novel view synthesis from sparse input images is rarely all reconstruction or all generation: pixels visible in some source view have a unique correct value modulated only by view-dependent shading, while pixels in disocclusions or beyond the captured volume admit a distribution of plausible completions. Existing generative novel-view-synthesis methods conflate these regimes under a single uniform loss, blurring the line between geometric fidelity and creative hallucinations even when scene geometry is injected through warped point clouds or projected depth. We introduce GenRec, a multi-view flow matching model that builds the reconstruction--generation split directly into its architecture, supervision, and gradient flow. Guided by an observation mask derived from the source cameras and a monocular depth estimator, a flow matching backbone jointly denoises RGB and scene-coordinate maps across all target views, while a pixel-space refinement stage restores high-frequency detail on observed pixels; the same mask gates supervision so regression signals do not contaminate the generative prior. Across RealEstate10K, DL3DV-10K, and Mip-NeRF~360, in both single-view extrapolation and two-view interpolation, GenRec attains the best reconstruction fidelity in observed regions while also surpassing purely generative baselines on perceptual quality in unobserved ones, showing the effectiveness of our approach. The source code and trained models will be made public.

Poster
GazeFlow: From Human Gaze Behavior to Generative Egocentric Gaze Prediction

sheng zhao, Weikai Lin, Yuhao Zhu

展开摘要

Egocentric gaze prediction enables many downstream applications but remains challenging, as human gaze is inherently stochastic. This stochasticity is constrained by structured temporal dynamics alternating between fixations and saccades, top-down influences from tasks, and bottom-up visual saliency. Based on this observation, we introduce GazeFlow, a framework that directly models gaze as a joint distribution of temporal gaze positions conditioned upon both top-down and bottom-up information. In particular, GazeFlow uses conditional flow matching (CFM): a learned velocity field iteratively transports a Gaussian noise sample into a plausible gaze trajectory drawn from this joint distribution. The velocity field is conditioned on bottom-up visual features extracted by a video encoder and on top-down task information obtained by globally querying these features. On standard datasets, GazeFlow achieves state-of-the-art performance on per-frame metrics, and the generated trajectories align better with human gaze temporal dynamics.

Poster
GWScore: A structural diversity metric for consistent text-to-image generation

Francis Snelgar, Stephen Gould, Liang Zheng, Akshay Asthana

展开摘要

Recent advances in visual storytelling have leveraged powerful text-to-image diffusion models to generate sequences of images featuring consistent subjects and styles. While such methods achieve impressive identity preservation across the sequence, they often produce scenes with limited structural diversity---images that are overly similar in subject pose and spatial layout. Existing evaluation protocols primarily measure identity consistency using metrics such as DreamSim, which can inadvertently conflate identity preservation with subject pose. The inability to independently evaluate structural diversity inhibits progress on identity preserving image generation methods. We address this limitation by introducing a new metric based on the Gromov Wasserstein distance to quantify structural diversity independently of identity. Our metric provides an interpretable and generalizable measure of spatial variation across generated images, enabling a more balanced assessment of identity consistency and pose diversity. Using this framework, we systematically evaluate several recent visual storytelling and subject-consistent generation methods. Furthermore, we evaluate the effect of latent initialization methods on structural diversity in several popular text-to-image models.

Poster
GRASP: Guided Residual Adapters with Sample-wise Partitioning

Felix Nützel, Mischa Dombrowski, Bernhard Kainz

展开摘要

Text-to-image flow matching transformers degrade sharply in long-tail settings: tail-class outputs collapse in fidelity and diversity, limiting their value as synthetic augmentation for rare conditions. We trace this to low head-versus-tail gradient alignment during fine-tuning, an optimization-level pathology that conditioning- and sampling-side interventions do not address. We propose GRASP (Guided Residual Adapters with Sample-wise Partitioning): a deterministic partition of the conditioning space, paired with group-specific residual adapters in the transformer feedforward layers, that leaves the flow-matching objective and the sampler untouched. In conditional flow matching, condition values index distinct sets of probability paths, so partitioning along the conditioning is the structurally correct factorization suitable as gradient alignment proxy. Because the partition is static, every tail sample is guaranteed to update its assigned expert, which bypasses extreme longtail failure modes. Crucially, GRASP is non-invasive and composable: on MIMIC-CXR-LT, combining GRASP with self-guided minority sampling at inference time yields the best all-labels IRS we observe, beyond either intervention alone. GRASP itself reduces overall FID by up to 80\% and lifts tail-class coverage by up to 44\% over full fine-tuning, learned-routing MoE, and minority guidance. Used as training data for a downstream DenseNet classifier on NIH-CXR-LT, GRASP synthetics significantly outperform every non-GRASP alternative on macro F1, match the macro F1 obtained from real training data, and yield nonzero F1 on $9$ of $13$ classes versus $3$ of $13$ from full fine-tuning. Results on ImageNet-LT confirm the mechanism is not tied to medical inductive bias.

Poster
GOLIATH: Gradient Inversion of Tabular Diffusion Models

Giulio Segalini, Aditya Shankar, Jérémie Decouchant, Lydia Chen

展开摘要

Gradient inversion reconstructs training data from shared gradients. However, existing methods target classification tasks and image diffusion, and do not address mixed tabular diffusion, where numerical columns follow Gaussian noising while categorical columns are corrupted by discrete masks. This mixed continuous-discrete training objective changes both the inversion target and the gradient structure: an attacker must recover not only rows, timesteps, and noise, but also the latent mask pattern whose density is tied to the diffusion timestep. We propose Goliath, the first gradient inversion attack designed for tabular diffusion models. Goliath employs a cyclic inversion loop that jointly recovers rows and diffusion latents across Gaussian and mixed diffusion regimes. We introduce a tabular-aware objective function that balances numerical and categorical gradient contributions while improving categorical recovery through enforced consistency between noise levels and mask structures. To accommodate large batches, we aggregate multiple reconstructions across epochs using a row-alignment heuristic. Evaluated across nine tabular datasets, Goliath achieves up to $88.9\\%$ per-cell reconstruction accuracy and consistently outperforms gradient-inversion baselines across Gaussian and mixed tabular diffusion. Code is available at https://anonymous.4open.science/r/fl-tab-diffusion-inversion-F4E7/README.md.

Poster
GOLD: Geometric Optimized Latent Diffusion for Structure-Aware RNA Inverse Folding

Qi Si, Xuyang Liu, Penglei Wang, Shuo Su, Limei Han, Mengzhu Li, Xin Guo, Yuan Qi, Yuan Cheng

展开摘要

Designing RNA sequences that fold into specific 3D structures is a fundamental challenge in therapeutics. Current RNA inverse folding methods typically condition on 3D backbone coordinates but the generation is limited to 1D discrete sequences. This ignores the continuous side-chain orientations, which are essential for overall structural stability. To address this issue, we explicitly introduce side-chain geometry into the RNA generative process. Unlike co-design frameworks that diffuse across separate raw spaces, we propose Geometric Optimized Latent Diffusion (\textbf{GOLD}), which project sequence and structure into a unified latent manifold. GOLD employs a novel GeoVAE to elegantly integrate discrete RNA sequences with continuous side-chain angles. By mapping these modalities into a single, smooth latent manifold, GOLD naturally facilitates a synergistic co-diffusion process. To enhance structural validity, we further introduce a training-free, gradient-guided sampling mechanism. By decoding the generated sequence probabilities and side-chain geometries into structures during the sampling process, we compute analytical gradients from physical constraints. This dynamic feedback actively guides the generated sequence to a physically stable state. Extensive experiments validate the superiority of GOLD, achieving state-of-the-art performance across sequence recovery, secondary structure validity, and 3D foldability metrics.

Spotlight
GEOPHYS: The Geometry of Physical Plausibility

Christian Internò, Alexander Pondaven, Habon Issa, Fabio Pizzati, Francesco Pinto, Markus Olhofer, Ivan Laptev, Philip Torr, Eero Simoncelli, Barbara Hammer, David Klindt

展开摘要

Whether a video is physically plausible is a question current generative models answer poorly and current evaluators answer expensively, through physics-targeted training, billion-parameter video world models, or multimodal-language model judges. We ask whether frozen images vision encoders, with no video or physics supervision, already contain a useful signal for the same question. Across four frozen backbones, self-supervised vision transformers (DINOv2, DINOv3) and biologically-inspired models of the ventral stream (CORnet-S, VOneNet), a small set of geometric signals (curvature, speed variation, acceleration, prediction residual) on per-frame feature trajectories separates plausible from physics violated videos with no retraining. We propose GEOPHYS, a training-free framework that 11 reaches 97.7% on LikePhys and 93.3% on IntPhys2 accuracy for physics-violation detection, surpassing V-JEPA 2, GPT-4o, Gemini, and twelve modern video diffusion models. The same signals track human EEG responses to object-permanence violations and scale with object number. Deployed unchanged as a best-of-N reward during video generation, GEOPHYS lifts MAGI-1 4.5B from 53.8\% to 64.7\% PhysicsIQ score at 5.8× lower wall-clock and 7.8× lower memory than V-JEPA 2 world-model rewards. A useful proxy for physical plausibility is already encoded as a geometric regularity of natural-video statistics in vision features.

Poster
GCD: GCM-consistent Diffusion for Zero-shot Downscaling across Heterogeneous GCMs

Ruian Tie, Wenbo Xiong, Zhengyu Shi, Xinyu Su, Libo Wu, Hao Li

展开摘要

Climate downscaling of global General Circulation Models (GCMs) is a challenging ill-posed inverse problem. In practice, the lack of paired data makes end-to-end supervised training infeasible, while downstream assessments require processing large, heterogeneous GCM ensembles under strict computational limits. Consequently, developing an efficient, zero-shot downscaling approach is crucial. While vanilla Diffusion Posterior Sampling has recently shown immense potential by bypassing paired training, it remains bottlenecked by geographic misalignments, spectral biases, and prohibitive inference costs. To address these limitations, we propose the GCM-consistent Diffusion for Zero-shot Downscaling (GCD) framework. First, GCD conditions the diffusion prior on static geographic boundaries to ensure physical fidelity. Second, we introduce a filter measurement operator, effectively mitigating spectral discrepancies between GCMs and the prior to provide stable inference-time guidance. Third, to overcome the inference bottleneck, we design a joint acceleration scheme: by combining progressive distillation with Conjugate Gradient guidance to correct large-step deviations, GCD compresses the generation process to just 6 steps. Extensive experiments demonstrate that GCD achieves highly competitive 99th percentile accuracy across five heterogeneous GCMs and successfully recovers the high-frequency details of tropical cyclones, entirely without model-specific retraining.

Poster
GARDO: Reinforcing Diffusion Models without Reward Hacking

Haoran He, Yuxiao Ye, Jie Liu, Jiajun Liang, Zhiyong Wang, Ziyang Yuan, Xintao Wang, Hangyu Mao, Meng Wang, Pengfei Wan, Ling Pan

展开摘要

Fine-tuning diffusion models via online reinforcement learning (RL) has shown great potential for enhancing text-to-image alignment. However, since precisely specifying a ground-truth objective for visual tasks remains challenging, the models are often optimized using a proxy reward that only partially captures the true goal. This mismatch often leads to reward hacking, where proxy scores increase while real image quality deteriorates and generation diversity collapses. While common solutions add regularization against the reference policy to prevent reward hacking, they compromise sample efficiency and impede the exploration of novel, high-reward regions, as the reference policy is usually sub-optimal. To address the competing demands of sample efficiency, effective exploration, and mitigation of reward hacking, we propose \textbf{G}ated and \textbf{A}daptive \textbf{R}egularization with \textbf{D}iversity-aware \textbf{O}ptimization (\textbf{GARDO}), a versatile framework compatible with various RL algorithms. Our key insight is that regularization need not be applied universally; instead, it is highly effective to selectively penalize a subset of samples that exhibit high uncertainty. To address the exploration challenge, GARDO introduces an adaptive regularization mechanism wherein the reference model is periodically updated to match the capabilities of the online policy, ensuring a relevant regularization target. To address the mode collapse issue in RL, GARDO amplifies the rewards for high-quality samples that also exhibit high diversity, encouraging mode coverage without destabilizing the optimization process. Extensive experiments across diverse proxy rewards and hold-out unseen metrics consistently show that GARDO mitigates reward hacking and enhances generation diversity without sacrificing sample efficiency or exploration, highlighting its effectiveness and robustness.

Poster