REVIEW 4 major objections 4 minor 22 references
Enhancing Financial VQA in Vision Language Models using Intermediate Structured Representations
T0 review · 4 major / 4 minor · reviewed 2026-08-10 · deepseek-v4-flash
Pith's one-line read Structured tables extracted from chart images, rather than the images themselves, sharply improve vision-language model reasoning on financial bar-chart questions, and fine-tuning DePlot on synthetic bar charts is enough to realize the…
desk verdict Clean internal result on same-distribution synthetic charts, but the financial-VQA generalization claim needs out-of-distribution evidence and released artifacts before it persuades. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is DePlot, a modality-conversion module that turns a chart image into a linearized table string, using '|' to separate columns and '<0x0A>' to mark row ends. The authors fine-tune DePlot on a custom 50,000-image dataset of financial bar charts, then feed the resulting tables to downstream LLMs alongside the image. The evaluation uses Relative Mapping Similarity (RMS), which measures how well predicted row-and-column-to-value mappings align with ground truth, and Relative Number Set Similarity (RNSS), which checks numerical sets; these metrics make the improvement in table fidelity legible and connect the table-extraction step to the downstream QA gains.
What would settle it
Take a set of real financial charts from filings, earnings reports, or financial news with manually verified ground-truth values, run the fine-tuned table extractor and the same table-plus-image LLM setup on them, and compare MAPE and RMS F1 against the synthetic-test numbers; if the advantage over image-only queries shrinks or disappears, the claim that the gains carry outside the synthetic distribution is refuted.
Extended reading notes
Core claim
The central claim is that accurate intermediate structured representations are the bottleneck for chart question answering: once a chart is correctly rendered as a table, LLM reasoning over that table is dramatically better than over the image, and fine-tuning the table extractor on domain-specific synthetic charts is enough to make this work. The authors demonstrate that base DePlot produces tables with poor categorical alignment, reaching an RMS F1 of 50.93%, while the fine-tuned model reaches 91.06% on the same 1,000-image test set. Downstream, adding the fine-tuned table lowers Qwen2-VL-7B's MAPE from 32.63% to 2.98% and its RMSE from 90.99% to 8.10%, and it lets smaller models such as Qwen2-VL-7B and Llama-3.2-11B outperform GPT-4o when GPT-4o is given only the raw image. The paper presents this as evidence that the quality of the table, not the scale of the reasoning model, drives numerical question-answering performance.
Load-bearing premise
The whole result rests on the assumption that the synthetic bar charts used for training and testing behave like real-world financial charts; if real charts differ in layout, noise, or encoding, the measured accuracy gains may not transfer.
Editorial extensions
If this is right
- Fine-tuning a chart-to-table model on domain-specific synthetic charts can produce large gains in table fidelity, with RMS F1 rising by roughly 40 percentage points, without changing the downstream LLM.
- Providing a high-quality table alongside the image reduces MAPE for all tested LLMs, and the relative reduction is largest for the smaller models.
- With structured tables, smaller vision-language models can beat a much larger model, GPT-4o, that reads the image directly.
- Because a correct table is the key input, the quality of the intermediate representation, rather than model scale, dominates numerical QA performance in this setting.
- The same dataset-generation recipe, with domain-specific labels and values, is claimed to extend the approach to other domains such as healthcare or marketing charts.
Reading between the lines
- If table quality is truly the bottleneck, then any reliable chart-to-table system, not just DePlot, should reproduce the same downstream gains, making the claim testable in a model-agnostic way.
- The large improvement likely reflects the LLM's difficulty in reading exact numeric values from images; once the table removes perceptual noise, residual errors should track table-extraction accuracy rather than image understanding.
- Because training and test charts come from the same randomized generator, the measured gains probably overestimate performance on real-world charts with noise, OCR errors, and complex encodings; testing on real financial report pages would clarify this.
- The same table-first recipe could be applied to other structured visual inputs, such as line charts, scatter plots, or diagrams, wherever a textual derendering of the visual exists.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes fine-tuning DePlot on 50,000 synthetic financial bar charts (simple, stacked, and grouped) and using the resulting tables as intermediate structured representations for question answering with vision-language models and LLMs. It reports that fine-tuned DePlot improves RNSS from 89.67% to 98.07% and RMS F1 from 50.93% to 91.06% on a held-out set from the same generator, and that providing the fine-tuned table to GPT-4o, Qwen2-VL-2B/7B, and LLaMa-11B reduces MAPE and RMSE relative to image-only prompting. An appendix provides qualitative examples comparing base and fine-tuned tables, along with zero-shot VLM inference on three charts.
Significance. The central idea—domain-adaptive fine-tuning of a plot-to-table module to improve downstream numerical reasoning—is sensible, and the internal experiments are self-consistent, providing a clear proof-of-concept on the synthetic distribution. The paper describes the dataset generation and metrics in enough detail to be reproduced in principle, and it explicitly defines the RNSS and RMS scoring rules. However, the central claim is about financial VQA broadly, and the evidence is entirely from a single synthetic generator with a fixed vocabulary and layout distribution. The paper's own limitations paragraph concedes the absence of evaluation on complex or out-of-distribution charts. Consequently, the headline numbers should be read as distribution-specific results, not as established generalization. The approach merits publication only after external validation on a public chart benchmark or real financial documents.
major comments (4)
- [§5.3, §8, Table IV] The training, test, and QA charts are all produced by the same Matplotlib/Seaborn generator with a fixed financial vocabulary (Section 5.1), and the QA pairs are generated from the same ground-truth tables. Because the fine-tuned DePlot is tested on images that share fonts, colors, label sets, and value ranges with training, the large improvements (RMS F1 50.93% to 91.06%; Qwen-7b MAPE 32.63% to 2.98%) may substantially reflect fitting the generator's distribution rather than general chart-reading ability. The limitations paragraph in Section 7 explicitly acknowledges that the model has not been evaluated on more complex visualizations and that domain-specific fine-tuning may limit generalization. To support the paper's general claim, an out-of-distribution evaluation on a public chart benchmark (e.g., ChartQA, ChartOCR, or a collection of real financial charts) is required; without it, the external-validity gap is load-bearing.
- [§6.2 vs. Table III] The base DePlot average RNSS is reported as 89.67% in the text of Section 6.2, but Table III lists it as 86.67%. This discrepancy is not explained, and it directly affects the reported RNSS improvement of "approximately 8.4 percentage points" in Section 8.1. The authors should correct the inconsistent number and recompute the gain consistently, or justify why the two values differ.
- [Table IV and §9.2] The QA results are point estimates from a single run over 100 charts, with no confidence intervals, error bars, or significance tests. Moreover, the base-table configuration is not consistently better than image-only: for GPT-4o, RMSE increases from 60.51 to 65.89, and for Qwen-2b, from 80.84 to 90.52. The statement that "transitioning from the image-only configuration to the fine-tuned table configuration consistently and significantly reduces both MAPE and RMSE" is supported for the fine-tuned table, but the base-table comparison should be reported with uncertainty and the negative cases should be discussed rather than swept into an average.
- [§7.3 and §7.2] The fine-tuning section specifies 10 epochs, AdamW, and an H100 GPU, but omits learning rate, batch size, gradient accumulation, warmup, the exact DePlot checkpoint used for initialization, and the input resolution or patch configuration (beyond the 1,024-patch limit). Without these details—and without code or dataset release—the fine-tuning results are difficult to reproduce independently. The authors should provide the full hyperparameter configuration and, ideally, release the dataset and trained checkpoints.
minor comments (4)
- [Section numbering] The conclusion is numbered "7" while Section 7 is "Fine-Tuning DEPLOT on the Custom Bar Chart Dataset"; subsequent sections continue to 9, so the numbering is inconsistent and should be renumbered.
- [§8.1 and Table II] The sentence "the fine-tuned model achieves its highest RNSS score of 98.07% and an RMS F1 score of 91.51% at epoch 6 and epoch 2, respectively" matches Table II, but Table III compares the fine-tuned model at epoch 6 for both metrics. Clarify whether the comparison model uses epoch-6 weights for RMS or the epoch-2 checkpoint, and why.
- [§6.1 equations] The matching matrix X in the RNSS and RMS equations is not fully specified; please state that it is obtained via a minimal-cost assignment, and give the value of the threshold parameter τ used for the Levenshtein-distance partial credit in RMS.
- [References] Reference [14] appears to have incomplete metadata (only a date is given); please provide a full citation. Also, reference [19] is repeated as reference [16] in spirit; check for duplicate or missing entries.
Circularity Check
No circularity: fine-tuning gains are measured on a held-out synthetic split; same-generator evaluation limits external validity but does not make the result definitionally circular.
full rationale
The paper's central empirical claims are (i) fine-tuning DePlot improves RMS F1 and RNSS on table extraction (Tables I–III) and (ii) providing the fine-tuned table Ft to LLMs reduces MAPE/RMSE relative to image-only queries (Table IV). These are measured on a held-out test set of 1,000 images plus 100 QA charts that are disjoint from the 50,000-image training set described in Sections 5, 7, and 9. The reported scores compare model outputs to ground-truth tables and QA answers; they are not parameters fitted to the test set and then relabeled as predictions. The fine-tuned DePlot weights are learned on the training split, and Ft is produced at inference on unseen images, so the downstream QA improvement is not forced by construction. The image-only condition never supplies the ground-truth table to the LLM, so the comparison between image-only and table-augmented conditions is meaningful. No load-bearing step reduces to a self-citation: references [1], [3], and [4] are external prior work by other authors, and no uniqueness theorem or ansatz is imported from the present authors' prior publications. The manuscript's own limitations paragraph concedes that the model 'has not been thoroughly evaluated on more complex visualizations' and that 'domain-specific fine-tuning may limit generalization to unfamiliar chart types.' That is a genuine external-validity caveat — training and test charts come from the same randomized Matplotlib/Seaborn generator, so the measured gains partly reflect learning that generator's distribution — but it is a correctness/generalization risk, not a circularity risk under the specified criteria, because the evaluation is held-out and the claimed quantities are not equivalent to the inputs by definition. Accordingly, no circular step is present and the circularity score is 0.
Assumptions & free parameters
free parameters (3)
- Chart-type split in fine-tuning set =
50% simple, 30% stacked, 20% grouped
- RNSS tolerance threshold =
10%
- Image patch budget =
1024 patches
assumptions (3)
- domain assumption Synthetic charts represent real financial bar charts
- domain assumption Ground-truth tables exactly describe the rendered images
- domain assumption DePlot's pretrained weights are a sound starting point
Cite this review
Pith. "Pith review of Enhancing Financial VQA in Vision Language Models using Intermediate Structured Representations." pith.science (2026). https://pith.science/paper/IL4XMSSD
@misc{pith2026250104675,
author = {Pith},
title = {Pith review of: Enhancing Financial VQA in Vision Language Models using Intermediate Structured Representations},
year = {2026},
howpublished = {\url{https://pith.science/paper/IL4XMSSD}},
note = {Machine review of arXiv:2501.04675}
}
read the original abstract
Chart interpretation is crucial for visual data analysis, but accurately extracting information from charts poses significant challenges for automated models. This study investigates the fine-tuning of DEPLOT, a modality conversion module that translates the image of a plot or chart to a linearized table, on a custom dataset of 50,000 bar charts. The dataset comprises simple, stacked, and grouped bar charts, targeting the unique structural features of these visualizations. The finetuned DEPLOT model is evaluated against its base version using a test set of 1,000 images and two metrics: Relative Mapping Similarity (RMS), which measures categorical mapping accuracy, and Relative Number Set Similarity (RNSS), which evaluates numerical interpretation accuracy. To further explore the reasoning capabilities of large language models (LLMs), we curate an additional set of 100 bar chart images paired with question answer sets. Our findings demonstrate that providing a structured intermediate table alongside the image significantly enhances LLM reasoning performance compared to direct image queries.
Figures
Figures from the paper (7 more)
Reference graph
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You are a helpful assistant. Help me with my math homework!
Citibank’s Capital Value is 950, while Mizuho Bank’s Capital Value is 800. Pixtral-12B-2409 [18] The value of Reserves is approximately -30, and the value of Cash is approxi- mately -35. So, the difference in value between Reserves and Cash is 5. Hokkoku Bank, Projections: 100...
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The difference in value between Reserves and Cash is: -30 - (-20) = -10 Therefore, the difference in Value between Reserves and Cash is -10
To find the difference, I’ll subtract Mizuho Bank’s Capital from Citibank’s Capital.1000 (Citibank’s Capital) - 800 (Mizuho Bank’s Capital) = 200 Molmo-7B-D-0924 [17] The Value of Reserves is -30 and the Value of Cash is -20. The difference in value between Reserves and Cash i...
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Reviewed August 10, 2026 · model on record in the stance chip above.
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