MMGraphRAG: Bridging Vision and Language with Interpretable Multimodal Knowledge Graphs

Retrieval-Augmented Generation (RAG) enhances language model generation by retrieving relevant information from external knowledge bases. However, conventional RAG methods face the issue of missing multimodal information. Multimodal RAG methods address this by fusing images and text through mapping them into a shared embedding space, but they fail to capture the structure of knowledge and logical chains between modalities. Moreover, they also require large-scale training for specific tasks, resulting in limited generalizing ability. To address these limitations, we propose MMGraphRAG, which refines visual content through scene graphs and constructs a multimodal knowledge graph (MMKG) in conjunction with text-based KG. It employs spectral clustering to achieve cross-modal entity linking and retrieves context along reasoning paths to guide the generative process. Experimental results show that MMGraphRAG achieves state-of-the-art performance on the DocBench and MMLongBench datasets, demonstrating strong domain adaptability and clear reasoning paths.