Twin-T & TwintVQA: A Reliable Structure-Detail Separating VLM and a Comprehensive Benchmark for Chart and Table Tasks

Abstract

With the rapid development of Vision-Language Models (VLMs), there is a growing demand for automatic analysis of structured visual data. Charts and tables carry quantitative information through regular layouts, explicit numbers, and chart-specific reading patterns, yet current VLMs still underuse these properties, often causing value errors and unreliable analysis. To overcome these limitations, we propose Twin-T, a two-stage expert VLM for comprehensive chart-table tasks across Image, LaTeX, and Python. In stage 1, we propose a dual-head image encoder that can separate structural cues and fine details from input images. In stage 2, we propose MINT, a preference learning method that emphasizes numerical and keyword fidelity, as well as vision-text matching. Furthermore, we introduce a comprehensive TwintVQA benchmark with 17 chart types, 11 task types, 3 data formats, and short / medium / long QA settings. Our model narrows the gap between open-source and closed-source models on mainstream chart-table benchmarks, outperforming open-source models while even remaining competitive with GPT-4o and Gemini-2.5-Pro.