@inproceedings{alon-etal-2026-tabstructor,
title = "Tabstructor: Reconstructing Latent Borders in Borderless and Partially Ruled Tables",
author = "Alon, Alvin Sarraga and
De Rosa, Daniele and
Friedl, Johannes and
Batista-Navarro, Riza",
editor = "T.Y.S.S., Santosh and
Agarwal, Amit and
Gupta, Vivek and
Kementchedjhieva, Yova and
Garimella, Aparna and
Hou, Yufang",
booktitle = "The Proceedings of Workshop on Document Intelligence and Understanding",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.docinsights-1.18/",
pages = "244--272",
ISBN = "979-8-89176-477-4",
abstract = "Borderless and partially ruled scientific tables often omit visual boundaries that mark logical rows, columns, and spanning regions. We introduce Tabstructor, a vision{--}language framework for latent-border reconstruction: predicting a table bounding box and horizontal and vertical segments representing logical boundaries even when visually absent or incomplete. On a held-out external test set, we compare task-specific prompting of a frozen base model, supervised fine-tuning, structure-preserving augmentation, and optional OCR-assisted geometry refinement. We introduce the Latent Border Reconstruction Score (LBRS; 0{--}100, higher is better) for evaluating valid structural and geometric border recovery. Task-specific prompting improves the frozen model, while fine-tuning provides the dominant gain, increasing LBRS from 38.552 to 90.014 (paired gain 51.462; 95{\%} paired-bootstrap CI: 45.583{--}57.259). The augmented predictor reaches 93.487, a further 3.473-point gain, although it receives additional cumulative training exposure. OCR-assisted refinement improves boundary localisation and extent but adds only 0.467 points on average (95{\%} CI: $-1.968${--}2.615) and can cause boundary-count regressions. Thus, fine-tuning performs the principal reconstruction, while refinement is an optional, non-uniform geometry adjustment."
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<abstract>Borderless and partially ruled scientific tables often omit visual boundaries that mark logical rows, columns, and spanning regions. We introduce Tabstructor, a vision–language framework for latent-border reconstruction: predicting a table bounding box and horizontal and vertical segments representing logical boundaries even when visually absent or incomplete. On a held-out external test set, we compare task-specific prompting of a frozen base model, supervised fine-tuning, structure-preserving augmentation, and optional OCR-assisted geometry refinement. We introduce the Latent Border Reconstruction Score (LBRS; 0–100, higher is better) for evaluating valid structural and geometric border recovery. Task-specific prompting improves the frozen model, while fine-tuning provides the dominant gain, increasing LBRS from 38.552 to 90.014 (paired gain 51.462; 95% paired-bootstrap CI: 45.583–57.259). The augmented predictor reaches 93.487, a further 3.473-point gain, although it receives additional cumulative training exposure. OCR-assisted refinement improves boundary localisation and extent but adds only 0.467 points on average (95% CI: -1.968–2.615) and can cause boundary-count regressions. Thus, fine-tuning performs the principal reconstruction, while refinement is an optional, non-uniform geometry adjustment.</abstract>
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%0 Conference Proceedings
%T Tabstructor: Reconstructing Latent Borders in Borderless and Partially Ruled Tables
%A Alon, Alvin Sarraga
%A De Rosa, Daniele
%A Friedl, Johannes
%A Batista-Navarro, Riza
%Y T.Y.S.S., Santosh
%Y Agarwal, Amit
%Y Gupta, Vivek
%Y Kementchedjhieva, Yova
%Y Garimella, Aparna
%Y Hou, Yufang
%S The Proceedings of Workshop on Document Intelligence and Understanding
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-477-4
%F alon-etal-2026-tabstructor
%X Borderless and partially ruled scientific tables often omit visual boundaries that mark logical rows, columns, and spanning regions. We introduce Tabstructor, a vision–language framework for latent-border reconstruction: predicting a table bounding box and horizontal and vertical segments representing logical boundaries even when visually absent or incomplete. On a held-out external test set, we compare task-specific prompting of a frozen base model, supervised fine-tuning, structure-preserving augmentation, and optional OCR-assisted geometry refinement. We introduce the Latent Border Reconstruction Score (LBRS; 0–100, higher is better) for evaluating valid structural and geometric border recovery. Task-specific prompting improves the frozen model, while fine-tuning provides the dominant gain, increasing LBRS from 38.552 to 90.014 (paired gain 51.462; 95% paired-bootstrap CI: 45.583–57.259). The augmented predictor reaches 93.487, a further 3.473-point gain, although it receives additional cumulative training exposure. OCR-assisted refinement improves boundary localisation and extent but adds only 0.467 points on average (95% CI: -1.968–2.615) and can cause boundary-count regressions. Thus, fine-tuning performs the principal reconstruction, while refinement is an optional, non-uniform geometry adjustment.
%U https://aclanthology.org/2026.docinsights-1.18/
%P 244-272
Markdown (Informal)
[Tabstructor: Reconstructing Latent Borders in Borderless and Partially Ruled Tables](https://aclanthology.org/2026.docinsights-1.18/) (Alon et al., DocInsights 2026)
ACL