Visual Programmability: A Guide for Code-as-Thought in Chart Understanding

Fuente: arXiv
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Autori principali: Tang, Bohao, Ma, Yan, Zhang, Fei, Su, Jiadi, Chern, Ethan, Hu, Zhulin, Wang, Zhixin, Liu, Pengfei, Zhang, Ya
Natura: Preprint
Pubblicazione: 2025
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author Tang, Bohao
Ma, Yan
Zhang, Fei
Su, Jiadi
Chern, Ethan
Hu, Zhulin
Wang, Zhixin
Liu, Pengfei
Zhang, Ya
author_facet Tang, Bohao
Ma, Yan
Zhang, Fei
Su, Jiadi
Chern, Ethan
Hu, Zhulin
Wang, Zhixin
Liu, Pengfei
Zhang, Ya
contents Chart understanding presents a critical test to the reasoning capabilities of Vision-Language Models (VLMs). Prior approaches face critical limitations: some rely on external tools, making them brittle and constrained by a predefined toolkit, while others fine-tune specialist models that often adopt a single reasoning strategy, such as text-based chain-of-thought (CoT). The intermediate steps of text-based reasoning are difficult to verify, which complicates the use of reinforcement-learning signals that reward factual accuracy. To address this, we propose a Code-as-Thought (CaT) approach to represent the visual information of a chart in a verifiable, symbolic format. Our key insight is that this strategy must be adaptive: a fixed, code-only implementation consistently fails on complex charts where symbolic representation is unsuitable. This finding leads us to introduce Visual Programmability: a learnable property that determines if a chart-question pair is better solved with code or direct visual analysis. We implement this concept in an adaptive framework where a VLM learns to choose between the CaT pathway and a direct visual reasoning pathway. The selection policy of the model is trained with reinforcement learning using a novel dual-reward system. This system combines a data-accuracy reward to ground the model in facts and prevent numerical hallucination, with a decision reward that teaches the model when to use each strategy, preventing it from defaulting to a single reasoning mode. Experiments demonstrate strong and robust performance across diverse chart-understanding benchmarks. Our work shows that VLMs can be taught not only to reason but also how to reason, dynamically selecting the optimal reasoning pathway for each task.
format Preprint
id arxiv_https___arxiv_org_abs_2509_09286
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Visual Programmability: A Guide for Code-as-Thought in Chart Understanding
Tang, Bohao
Ma, Yan
Zhang, Fei
Su, Jiadi
Chern, Ethan
Hu, Zhulin
Wang, Zhixin
Liu, Pengfei
Zhang, Ya
Computer Vision and Pattern Recognition
Chart understanding presents a critical test to the reasoning capabilities of Vision-Language Models (VLMs). Prior approaches face critical limitations: some rely on external tools, making them brittle and constrained by a predefined toolkit, while others fine-tune specialist models that often adopt a single reasoning strategy, such as text-based chain-of-thought (CoT). The intermediate steps of text-based reasoning are difficult to verify, which complicates the use of reinforcement-learning signals that reward factual accuracy. To address this, we propose a Code-as-Thought (CaT) approach to represent the visual information of a chart in a verifiable, symbolic format. Our key insight is that this strategy must be adaptive: a fixed, code-only implementation consistently fails on complex charts where symbolic representation is unsuitable. This finding leads us to introduce Visual Programmability: a learnable property that determines if a chart-question pair is better solved with code or direct visual analysis. We implement this concept in an adaptive framework where a VLM learns to choose between the CaT pathway and a direct visual reasoning pathway. The selection policy of the model is trained with reinforcement learning using a novel dual-reward system. This system combines a data-accuracy reward to ground the model in facts and prevent numerical hallucination, with a decision reward that teaches the model when to use each strategy, preventing it from defaulting to a single reasoning mode. Experiments demonstrate strong and robust performance across diverse chart-understanding benchmarks. Our work shows that VLMs can be taught not only to reason but also how to reason, dynamically selecting the optimal reasoning pathway for each task.
title Visual Programmability: A Guide for Code-as-Thought in Chart Understanding
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2509.09286