2026· Journal of Electronics and Information Science· 0 citations· 19 references
TL;DR
Results on the object hallucination evaluation benchmark POPE show that the proposed Dual-branch Inference for Visual-prior Elimination reduces the model’s hallucination rate when objects are dense or complex occlusions exist, and brings a slight improvement in the question-answering accuracy of the model on the MSCOCO and VG datasets.
Abstract
: When facing real-world scenes that are densely populated with objects or contain complex occlusions, Vision-Language Models are often constrained by the language prior in autoregressive decoding, producing severe hallucination phenomena. To address this pain point that limits the reliable deployment of large models, this paper proposes Dual-branch Inference for Visual-prior Elimination, a training-free hallucination mitigation mechanism for complex scenes. By constructing a dual-branch inference structure at the inference stage and introducing a dynamic visual-confidence penalty, this mechanism effectively quantifies and suppresses the overconfidence in the content generation process, forcing the model’s output to be deeply aligned with the underlying visual features. Results on the object hallucination evaluation benchmark POPE show that, without consuming computing power for model fine-tuning, the proposed method reduces the model’s hallucination rate when objects are dense or complex occlusions exist, and brings a slight improvement in the question-answering accuracy of the model on the MSCOCO and VG datasets.
This work studies hallucination from the perspective of dynamic representation shift during generation and proposes an online projection-based intervention on intermediate hidden states to suppress the hallucination-related directions, mitigating hallucinations while preserving language quality.
Object Hallucination in large vision-language models (LVLMs), where models generate non-factual content about input images, remains a critical barrier to their reliability in real-world applications. Existing mitigation strategies can be categorized into training-based and training-free methods. Training-based methods often achieve strong performance but are costly, requiring extensive computational resources, large-scale data, and time-consuming fine-tuning. Training-free approaches are particularly appealing due to their efficiency. However, existing training-free methods either require multiple decoding rounds, which adds computational overhead, or modify internal states in a model-specific way that risks degrading pretrained knowledge. We propose Test-Time Hallucination Mitigation (TTH) method, a novel training-free method that addresses both limitations. TTH introduces a token-validator module, implemented as a zero-shot Multi-Modal Classifier (MMC), to generate auxiliary logits grounded in the input image. These logits are fused with the original LVLM outputs at the token level for object tokens selected from a candidate pool. An entropy-based weighting scheme is then applied to enable robust and accurate predictions. Extensive experiments across multiple LVLM families and diverse benchmarks demonstrate that TTH consistently improves accuracy and robustness, underscoring its generalizability and practical effectiveness. Code is released at https://github.com/Mehran-TAM/TTH
Mehran Tamjidi, Hamidreza Dastmalchi, Ali Cheraghian et al.· 0 citations
Latent Attention Denoising (LAD) is introduced, a principled and training-free framework that recasts attention calibration as a one-step score-based denoising process that achieves superior performance on both generative and discriminative tasks.
Zhiwen Luo, Siyu Jiang, Weilong Jiang et al.· Annual Meeting of the Associ...· 0 citations
Vision-language models (VLMs) excel at open-ended captioning and visual QA but often describe objects, attributes, or relations absent from the image, a phenomenon known as object hallucination. We propose a {training-free, post-hoc representation editing technique} that operates in the representation space of the language backbone. The method performs a lightweight, one-time offline calibration on a modest paired dataset to estimate the required covariance structures, using only forward passes and empirical second-order statistics with no gradient updates or fine-tuning, after which the correction is absorbed directly into the model's existing weights. By modeling hidden states as a superposition of truthful and hallucination-associated components, we derive a Wiener-type estimator whose optimal gains are given in closed form from the covariances of paired truthful and hallucinated representations. An eigendecomposition yields mode-wise attenuation that respects a stability criterion, i.e., the filter responds continuously to estimation noise. The correction is applied once to the feed-forward output projections of selected deeper layers, at inference time, the model runs unchanged and at the same speed. Experiments on LLaVA-1.5, MiniGPT-4, Gemma3, and mPLUG-Owl2 demonstrate consistent reductions in object hallucination on CHAIR, POPE, and MME while maintaining caption fluency and overall response quality. We further demonstrate the generality of our approach on the TempCompass video understanding benchmark and on discrete diffusion language models for grounded dialogue, showing that representation filtering reduces hallucinations even in temporal video reasoning and multi-step, sequence-wide denoising settings.
Ameen Ali, Tamim Zoabi, Lidor Brami et al.· 0 citations
This work proposes CounterfactualLVLM, a training-free and plug-and-play framework that mitigates object hallucinations via small-model-assisted counterfactual reasoning and highlights the power of counterfactual guidance as a simple yet effective paradigm for enhancing factual grounding in LVLM-based multi-modal reasoning.
Xilin Li, Boyue Wang, Xiaoqian Ju et al.· Multimedia Systems· 0 citations
This work proposes a training-free hallucination mitigation framework for dynamic, per-instance suppression at test time, and proposes a dynamically combined projection that selectively suppresses the most probable hallucination directions while preserving image-grounded semantics.
Ali Cheraghian, Hamidreza Dastmalchi, Hamed Barzamini et al.· 0 citations