arXiv Preprint ยท ICLR 2026 Submission
HERS

Hidden-Pattern Expert Learning for
Risk-Specific Vehicle Damage Adaptation
in Diffusion Models

A domain-adaptive diffusion framework for forensically plausible, risk-aware vehicle damage synthesis in auto insurance, fraud detection, and claim verification workflows.

Teerapong Panboonyuen  ยท  kaopanboonyuen.github.io/HERS

HERS showcase โ€” generated vehicle damage samples

HERS ยท Generated samples demonstrating forensic damage fidelity across diverse vehicle types

Why visual realism alone is dangerous

Modern diffusion models can synthesize convincing car damage imagery โ€” but in safety-critical domains, surface realism is not enough. Auto insurance workflows demand semantic and forensic precision that generic generative models fundamentally lack.

โš–๏ธ

Liability at Stake

A single missing crack in synthesized evidence can flip liability decisions, alter claim outcomes, and expose insurers to financial loss.

๐Ÿ”

Fraud Analysis

Misplaced dents and incoherent damage patterns invalidate automated fraud detection systems trained on real-world accident imagery.

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Downstream Systems

Physically implausible damage patterns mislead claim processing pipelines, creating systemic errors at scale across insurance workflows.

Can diffusion models learn the semantic and forensic structure of vehicle damage โ€” not just its appearance?

โ€” Central research question driving HERS

Fine-Grained Damage Fidelity & Localized Consistency

A direct comparison between HERS and strong diffusion-based baselines including SD v1.5, SDXL, MoLE, VQ-Diffusion, and Versatile Diffusion across damage types and vehicle scenarios.

Figure 1 โ€” Qualitative damage fidelity comparison
Fig 01

HERS produces damage regions with higher visual fidelity and localized structural consistency. Fine-grained artifacts โ€” dents, cracks, torn bumpers, and paint abrasions โ€” are preserved under zoom, where competing models tend to smooth, misplace, or hallucinate damage textures, obscuring forensically critical cues.

Higher visual fidelity Localized structural consistency Forensic cue preservation Zoom-stable detail

The HERS Pipeline

HERS introduces a fully automated, self-supervised adaptation pipeline โ€” no manual annotation, no inference-time routing overhead. Specialization and generalization are unified in a single merged model.

Figure 2 โ€” HERS framework overview
Fig 02

Overview of the HERS adaptation framework showing LLM-driven prompt generation, text-to-image synthesis, damage-specific expert training, and expert merging into a unified model.

๐Ÿง 

Step 01

LLM-Driven Prompt Generation

Typical vehicle parts, accident narratives, and physically implausible scenarios to expose failure modes

๐Ÿ–ผ๏ธ

Step 02

Text-to-Image Synthesis

Base diffusion backbone generates diverse training imagery guided by structured prompts

โš™๏ธ

Step 03

Damage-Specific Expert Learning

Lightweight LoRA expert per damage type โ€” dent, scratch, crack, stain โ€” trained independently

๐Ÿ”—

Step 04

Expert Merging

All experts unified into a single model โ€” no routing, no manual labels, zero overhead at inference

Quantitative Results & Human Preference

HERS is evaluated across four expert-rated dimensions, consistently outperforming all baselines in both perceptual quality and semantic alignment.

โ†‘
Car Stain Quality
โ†‘
Car Damage Quality
โ†‘
Car Part Quality
โ†‘
Overall Image Quality
Key Finding

HERS improvements are not cosmetic โ€” they reflect better semantic alignment with real-world damage physics. Full-vehicle damage patterns remain consistent across panels, doors, and lighting conditions, making synthetic images indistinguishable from real accident photographs to human evaluators and automated systems alike.

State-of-the-art human preference Gains over MoLE & VD Semantic alignment

Beyond Generation: Dual-Use AI

HERS is not only a generative improvement โ€” it is a case study in the dual-use nature of domain-specific generative AI. High-fidelity damage synthesis enables powerful applications and simultaneously exposes real risks.

โœ… Enabling Applications

  • Rare-event simulation for model robustness
  • Large-scale data augmentation
  • Robust training for claim systems
  • Expert review and fraud simulation

โš ๏ธ Identified Risks

  • Fabricated accident evidence
  • Manipulated insurance claims
  • Synthetic fraud at scale
  • Adversarial inputs to automated systems

Domain-specific generative models must be paired with domain-specific safeguards.

โ€” HERS paper, Risk & Responsibility section

Key Technical Contributions

01

Introduce risk-specific diffusion adaptation for auto insurance โ€” the first framework targeting forensic plausibility in addition to visual realism.

02

Propose HERS, a self-supervised LoRA expert framework requiring no manual annotation and achieving specialization across four damage types within a single unified model.

03

Demonstrate state-of-the-art performance in text faithfulness, perceptual realism, and human preference across all evaluated damage categories and vehicle scenarios.

04

Expose the forensic implications of high-fidelity generative models in insurance workflows and argue for domain-specific safeguards as a research priority.

Paper

๐Ÿ“„

HERS: Hidden-Pattern Expert Learning for Risk-Specific Vehicle Damage Adaptation in Diffusion Models

arXiv Preprint ยท ICLR 2026 Submission

This research is the product of independent effort and vision, driven by the goal of advancing trustworthy generative AI for real-world, safety-critical systems.
@article{panboonyuen2026hers,
  title     = {HERS: Hidden-Pattern Expert Learning for
               Risk-Specific Vehicle Damage Adaptation
               in Diffusion Models},
  author    = {Panboonyuen, Teerapong},
  journal   = {arXiv preprint},
  year      = {2026},
  url       = {https://kaopanboonyuen.github.io/HERS}
}
T

Teerapong Panboonyuen

Independent Researcher ยท Trustworthy Generative AI

kaopanboonyuen.github.io/HERS