RAMQA: A Unified Framework for Retrieval-Augmented Multi-Modal Question Answering
Yang Bai, Christan Earl Grant, Daisy Zhe Wang
TL;DR
RAMQA tackles the gap between encoder-based ranking and decoder-based multi-modal LLMs in multi-modal QA by introducing a two-stage retrieval framework. It first uses RankLLaVA for pointwise multi-modal ranking, then applies RAMLLaMA, an autoregressive, instruction-tuned generator, to re-rank top-k candidates and produce answers, aided by zero-shot image-to-text data unification. The approach, validated on WebQA and MultimodalQA, yields state-of-the-art QA scores and EM/F1 improvements, driven by permutation-based generative retrieval and a multi-task objective. This work advances practical multi-modal IR by enabling end-to-end, efficient retrieval and generation with modern LLMs and provides a blueprint for integrating LTR and generative retrieval in multi-modal contexts.
Abstract
Multi-modal retrieval-augmented Question Answering (MRAQA), integrating text and images, has gained significant attention in information retrieval (IR) and natural language processing (NLP). Traditional ranking methods rely on small encoder-based language models, which are incompatible with modern decoder-based generative large language models (LLMs) that have advanced various NLP tasks. To bridge this gap, we propose RAMQA, a unified framework combining learning-to-rank methods with generative permutation-enhanced ranking techniques. We first train a pointwise multi-modal ranker using LLaVA as the backbone. Then, we apply instruction tuning to train a LLaMA model for re-ranking the top-k documents using an innovative autoregressive multi-task learning approach. Our generative ranking model generates re-ranked document IDs and specific answers from document candidates in various permutations. Experiments on two MRAQA benchmarks, WebQA and MultiModalQA, show significant improvements over strong baselines, highlighting the effectiveness of our approach. Code and data are available at: https://github.com/TonyBY/RAMQA
