We introduce a novel approach for calibrating uncertainty quantification (UQ) tailored for visual language models (VLMs). Existing state-of-the-art UQ methods rely on consistency among multiple responses, but often report higher confidence when the model is consistently incorrect, leading to poorly calibrated confidence. To address this, we leverage cross-modal consistency by grounding back the textual responses to visual inputs. The confidence from the grounding model (GM) is used to calibrate the overall confidence. Given that using a GM adds its own uncertainty, we apply temperature scaling to calibrate the GM’s confidence in the accuracy of the generated responses. We comprehensively evaluate the proposed approach across diverse range of settings, including datasets with varying visuo-linguistic complexity, Q&A and caption generation tasks, general visual and specialized medical contexts, VLMs differing in scale, openness, and different categories of GMs. Experimental results show that our approach consistently improves confidence calibration, with expected calibration error (ECE) improvements ranging from 32.5% to 96.7% over both self and non-self consistency-based baselines. Code is available here https://github.com/trilokpadhi/Multimodal-Uncertainty-Quantification.

Detecting toxicity in online multimodal environments, such as memes, remains a challenging task due to the complex contextual connections across modalities (e.g., text and visual), which demand both common-sense reasoning and contextual awareness. To bridge this gap, we propose a hybrid neurosymbolic framework that unifies (1) distillation of implicit contextual knowledge (e.g., sarcasm, cultural references) from Large Vision-Language Models (LVLMs) and (2) infusion of explicit relational semantics through sub-graphs from Knowledge Graphs (KGs). Experimental results on two benchmark datasets show the superior performance of our approach, Knowledge-Infused Distilled Vision-Language Model (KID-VLM), over the state-of-the-art baselines across AUC and F1, with improvements of 0.5%, and 10.6%, respectively, in HatefulMemes Benchmark across variants. Further, KID-VLM demonstrates better generalizability and achieves the best performance across all baselines in the HarMeme Dataset with a 6.3% and 3.2% in F1 and AUC.Given the contextual complexity of the toxicity detection, KID-VLM showcases the significance of learning compact models (~500M parameters) from both explicit (i.e., KG) and implicit (i.e., LVLMs) contextual cues incorporated through a hybrid neurosymbolic approach. Our codes and pretrained models are publicly available.