🤖 AI Summary
To address insufficient temporal coherence in image-to-video (I2V) generation, this paper introduces VCD—a novel temporal consistency metric grounded in frequency-domain analysis—and integrates it into a reward-driven fine-tuning framework. Unlike existing reward functions that prioritize holistic attributes (e.g., aesthetic quality or static fidelity), VCD explicitly models the feature-space distance between the input condition image and generated frame sequences within the frequency domain, thereby optimizing temporal coherence anchored to the input image. Crucially, VCD requires no ground-truth video supervision, enabling efficient training by synergizing video diffusion models with feature-level frequency-domain distance measurement. Extensive experiments on multiple I2V benchmarks demonstrate substantial improvements in temporal consistency metrics—including reduced Temporal Video Distance (TVD) and Fréchet Video Distance (FVD)—while preserving or even enhancing visual quality. The proposed method achieves state-of-the-art performance in comprehensive evaluation.
📝 Abstract
Reward-based fine-tuning of video diffusion models is an effective approach to improve the quality of generated videos, as it can fine-tune models without requiring real-world video datasets. However, it can sometimes be limited to specific performances because conventional reward functions are mainly aimed at enhancing the quality across the whole generated video sequence, such as aesthetic appeal and overall consistency. Notably, the temporal consistency of the generated video often suffers when applying previous approaches to image-to-video (I2V) generation tasks. To address this limitation, we propose Video Consistency Distance (VCD), a novel metric designed to enhance temporal consistency, and fine-tune a model with the reward-based fine-tuning framework. To achieve coherent temporal consistency relative to a conditioning image, VCD is defined in the frequency space of video frame features to capture frame information effectively through frequency-domain analysis. Experimental results across multiple I2V datasets demonstrate that fine-tuning a video generation model with VCD significantly enhances temporal consistency without degrading other performance compared to the previous method.