LeMon: Automating Portrait Generation for Zero-Shot Story Visualization with Multi-Character Interactions

Zero-Shot Story Visualization (ZSV) seeks to depict textual narratives through a sequence of images without relying on pre-existing text-image pairs for training. In this paper, we address the challenge of automated multi-character ZSV, aiming to create distinctive yet compatible character portraits for high-quality story visualization without the need of manual human interventions. Our study is motivated by the limitation of current ZSV approaches that necessitate inefficient manual collection of external images as initial character portraits and suffer from low-quality story visualization, especially with multi-character interactions, when the portraits are not well initiated. To overcome these issues, we develop LeMon, an LLM enhanced Multi-Character Zero-Shot Visualization framework that automates character portrait initialization and supports iterative portrait refinement by exploring the semantic content of the story. In particular, we design an LLM-based portrait generation strategy that matches the story characters with external movie characters, and leverage the matched resources as in-context learning (ICL) samples for LLMs to accurately initialize the character portraits. We then propose a graph-based Text2Image diffusion model that constructs a character interaction graph from the story to iteratively refine the character portraits by maximizing the distinctness of different characters while minimizing their incompatibility in the multi-character story visualization. Our evaluation results show that LeMon outperforms existing ZSV approaches in generating high-quality visualizations for stories across various types with multiple interacted characters. Our code is available at https://github.com/arxrean/LLM-LeMon.