arXiv:2502.04923cs.CVcs.AI2025-02ICLR被引 14

通过频率分析优化LoRA顺序,提升多概念图像生成质量。

Cached Multi-Lora Composition for Multi-Concept Image Generation

  • 基于频域分析确定LoRA融合顺序,减少语义冲突。
  • 实验显示CLIPScore提升2.19%,MLLM胜率提高11.25%。
  • 无需训练,支持高效多LoRA组合,适合风格/角色混搭场景。

低秩适配(LoRA)已成为文生图模型中实现多概念图像生成的主流技术,可精确渲染角色、风格等不同元素。然而,现有方法在组合多个LoRA时面临显著挑战,导致生成图像质量下降。本文从傅里叶频域角度研究LoRA在去噪过程中的作用,发现部分LoRA增强高频特征(如边缘、纹理),而另一些则聚焦低频成分(如整体结构、平滑渐变)。基于此,我们提出一种基于频域的序列策略,以确定推理时最优的LoRA集成顺序。为充分发挥该策略优势,我们设计了无需训练的缓存式多LoRA框架——CMLoRA,其采用灵活的骨干结构与针对各LoRA的非均匀缓存机制,有效缓解语义冲突并提升计算效率。实验表明,相比LoraHub、LoRA Composite和LoRA Switch等先进方法,CMLoRA在CLIPScore上平均提升2.19%,在MLLM胜率上提升11.25%。

原文摘要 · Abstract (English)

Low-Rank Adaptation (LoRA) has emerged as a widely adopted technique in text-to-image models, enabling precise rendering of multiple distinct elements, such as characters and styles, in multi-concept image generation. However, current approaches face significant challenges when composing these LoRAs for multi-concept image generation, resulting in diminished generated image quality. In this paper, we initially investigate the role of LoRAs in the denoising process through the lens of the Fourier frequency domain. Based on the hypothesis that applying multiple LoRAs could lead to "semantic conflicts", we find that certain LoRAs amplify high-frequency features such as edges and textures, whereas others mainly focus on low-frequency elements, including the overall structure and smooth color gradients. Building on these insights, we devise a frequency domain based sequencing strategy to determine the optimal order in which LoRAs should be integrated during inference. This strategy offers a methodical and generalizable solution compared to the naive integration commonly found in existing LoRA fusion techniques. To fully leverage our proposed LoRA order sequence determination method in multi-LoRA composition tasks, we introduce a novel, training-free framework, Cached Multi-LoRA (CMLoRA), designed to efficiently integrate multiple LoRAs while maintaining cohesive image generation. With its flexible backbone for multi-LoRA fusion and a non-uniform caching strategy tailored to individual LoRAs, CMLoRA has the potential to reduce semantic conflicts in LoRA composition and improve computational efficiency. Our experimental evaluations demonstrate that CMLoRA outperforms state-of-the-art training-free LoRA fusion methods by a significant margin -- it achieves an average improvement of $2.19\%$ in CLIPScore, and $11.25\%$ in MLLM win rate compared to LoraHub, LoRA Composite, and LoRA Switch.

LoRA融合图像生成频域分析多概念

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