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Consensus Entropy: Harnessing Multi-VLM Agreement for Self-Verifying and Self-Improving OCR
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Proposes Consensus Entropy, a training-free metric measuring multi-VLM output agreement to verify OCR outputs, and CE-OCR, an ensemble-and-route framework that improves OCR accuracy while routing a small fraction of inputs to a stronger VLM.
Problem
VLMs make sample-level OCR errors that are hard to detect, and existing evaluation relies on benchmark averages or VLM-as-Judge, which cannot reliably verify visual-text consistency without labels.
Approach
Measure the entropy of pairwise output similarities across several independent VLMs: correct predictions converge in output space while errors diverge. Low consensus entropy triggers a weighted ensemble; high entropy routes the sample to a stronger VLM for rephrasing.
Key results
- On a 1K human-annotated PDF page set, CE achieves F1 of 48.0-51.3 vs 36.1-40.0 for VLM-as-Judge, a 15.2-point (42.1%) average gain for quality verification.
- CE-OCR routing (Qwen2.5-VL-72B rephrase) reaches 922 on OCRBench vs 888 for best single model (+8.2%), routing 7.3% of inputs.
- CE-Ensemble on OCRBench-V2 English OCR improves from 65.6 (InternVL2.5-26B) to 67.2 and Math from 47.7 to 50.1 (Gemini Pro baseline row).
Surprising findings
- Ensembles of small open-source VLMs (<10B) such as Ovis2-1B-based combinations can outperform larger closed-source SOTA models on OCRBench.
- ROVER discrete voting fails catastrophically on open-ended VLM tasks (Doc-VQA -42.1%, Math-VQA -92.0%).
Limitations
- Gains depend on ensemble diversity; identical-model sampling gives smaller gains and results vary across sampling runs.
- GPT-4o verbose outputs artificially inflate CE values, requiring output cleaning for monotonic behavior.
- Threshold theta (around 0.5) is calibrated on development data and task-dependent metric choice (edit vs cosine) is required.
Experimental setup
Datasets: OCRBench OCRBench-V2 CCOCR
Benchmarks: OCRBench OCRBench-V2 CCOCR
Metrics: F1 accuracy cumulative score
Baselines: VLM-as-Judge VL-Uncertainty Single Model Self-Consistency ROVER CE-Ensemble
Builds on: self-consistency ROVER VL-Uncertainty VLM-as-Judge
Closest papers by meaning
- PP-OCRv5: A Specialized 5M-Parameter Model Rivaling Billion-Parameter Vision-Language Models on OCR Tasks (CVPR 2026 · similarity 0.87)
- OCRBench v2: An Improved Benchmark for Evaluating Large Multimodal Models on Visual Text Localization and Reasoning (NeurIPS 2025 · similarity 0.86)
- MME-VideoOCR: Evaluating OCR-Based Capabilities of Multimodal LLMs in Video Scenarios (NeurIPS 2025 · similarity 0.85)
- OCR-Reasoning Benchmark: Unveiling the True Capabilities of MLLMs in Complex Text-Rich Image Reasoning (ICLR 2026 · similarity 0.84)
- UPOCR: Towards Unified Pixel-Level OCR Interface (ICML 2024 · similarity 0.84)
- Seeing is Believing? Mitigating OCR Hallucinations in Multimodal Large Language Models (NeurIPS 2025 · similarity 0.84)
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