Title: Boost the Identity-Preserving Embedding for Consistent Text-to-Image Generation
Primary area: generative models
Keywords: Generative Models, Consistent Generation, Personalized Image Generation, Controllable Generation

Abstract: Diffusion-based text-to-image (T2I) models have advanced high-fidelity content generation, but their inability to maintain subject consistency—preserving a target’s identity and visual attributes across diverse scenes—hampers real-world applications. Existing solutions face critical limitations: training-based methods rely on heavy computation and large datasets; training-free approaches, while avoiding retraining, demand excessive memory or complex auxiliary modules. In this paper, we first reveal a key property overlooked in prior works that the identity-relevant signals, termed Identity-Preserving Embeddings (*IPemb*), are implicitly encoded in textual embeddings of frame prompts. To address the consistent T2I generation with the *IPemb* embedding, we propose Boost Identity-Preserving Embedding (*BIPE*), a training-free yet plug-and-play framework that explicitly extracts and enhances the *IPemb*. Its core innovations are two complementary techniques: Adaptive Singular-Value Rescaling (*adaSVR*) and Union Key (*UniK*). *adaSVR* applies singular-value decomposition to the joint embedding matrix of all frame prompts, amplifying identity-centric components (dominant matrix features) while suppressing frame-specific noise; crucially, it is integrated into every text encoder transformer layer to prevent *IPemb* dilution during non-linear feature transformations. *UniK* further reinforces consistency by concatenating cross-attention keys from all frame prompts (not just the current one), aligning the T2I backbone’s image-text attention across the entire generation sequence. Experiments on the *ConsiStory+* benchmark demonstrate *BIPE* outperforms state-of-the-art methods in both qualitative and quantitative metrics. To address the gap in evaluating a broader range of scenarios with diversified prompt templates, we introduce *DiverStory*, which confirm the scalability of *BIPE*.