ViCo: Towards Visual-oriented Coding with Self-Reflection for Chart Replication

Jiaxin Duan, Dian Jiao, Shuai Zhao


Abstract
This paper addresses the challenge of generating high-quality academic charts that match the visual standards of human-authored papers. While existing AI agents can produce well-structured text and code, their generated visualizations often lack the stylistic and semantic fidelity of human designs. Advanced coding agents that employ self-reflection mechanisms exhibit poor visual reasoning and limited reflection following, resulting in sparse reward signals that severely undermine their reinforcement learning (RL). We propose ViCo, a training framework for visual-oriented coding that employs iterative reflections to align generated chart images progressively with the reference. We first introduce a self-supervised warm-up stage, which augments Monte Carlo Tree Search with consistency-based pruning to synthesize high-quality reflection trajectories, ensuring that each coding step strictly follows the outcomes of prior reflections. A multi-step RL algorithm is then developed on counterfactual baselines to estimate advantage for reflection and action steps within each refinement cycle, thereby addressing the reward sparsity problem. To enable efficient reward in massive training, we propose an automatic, multifaceted evaluation framework that assesses charts’ style, layout, and semantic consistency via a hierarchical heterogeneous layout graph structure. Experiments on three public benchmarks demonstrate that ViCo, trained on an 8B model, achieves performance close to commercial LLMs with adequate reflection capabilities.
Anthology ID:
2026.findings-emnlp.1926
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
41043–41071
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1926/
DOI:
Bibkey:
Cite (ACL):
Jiaxin Duan, Dian Jiao, and Shuai Zhao. 2026. ViCo: Towards Visual-oriented Coding with Self-Reflection for Chart Replication. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 41043–41071, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ViCo: Towards Visual-oriented Coding with Self-Reflection for Chart Replication (Duan et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1926.pdf