Cross-Modal Redundancy and the Geometry of Vision-Language Embeddings

Fuente: arXiv
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Auteurs principaux: Dhimoïla, Grégoire, Fel, Thomas, Boutin, Victor, Picard, Agustin
Format: Preprint
Publié: 2026
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author Dhimoïla, Grégoire
Fel, Thomas
Boutin, Victor
Picard, Agustin
author_facet Dhimoïla, Grégoire
Fel, Thomas
Boutin, Victor
Picard, Agustin
contents Vision-language models (VLMs) align images and text with remarkable success, yet the geometry of their shared embedding space remains poorly understood. To probe this geometry, we begin from the Iso-Energy Assumption, which exploits cross-modal redundancy: a concept that is truly shared should exhibit the same average energy across modalities. We operationalize this assumption with an Aligned Sparse Autoencoder (SAE) that encourages energy consistency during training while preserving reconstruction. We find that this inductive bias changes the SAE solution without harming reconstruction, giving us a representation that serves as a tool for geometric analysis. Sanity checks on controlled data with known ground truth confirm that alignment improves when Iso-Energy holds and remains neutral when it does not. Applied to foundational VLMs, our framework reveals a clear structure with practical consequences: (i) sparse bimodal atoms carry the entire cross-modal alignment signal; (ii) unimodal atoms act as modality-specific biases and fully explain the modality gap; (iii) removing unimodal atoms collapses the gap without harming performance; (iv) restricting vector arithmetic to the bimodal subspace yields in-distribution edits and improved retrieval. These findings suggest that the right inductive bias can both preserve model fidelity and render the latent geometry interpretable and actionable.
format Preprint
id arxiv_https___arxiv_org_abs_2602_06218
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cross-Modal Redundancy and the Geometry of Vision-Language Embeddings
Dhimoïla, Grégoire
Fel, Thomas
Boutin, Victor
Picard, Agustin
Computer Vision and Pattern Recognition
Machine Learning
Vision-language models (VLMs) align images and text with remarkable success, yet the geometry of their shared embedding space remains poorly understood. To probe this geometry, we begin from the Iso-Energy Assumption, which exploits cross-modal redundancy: a concept that is truly shared should exhibit the same average energy across modalities. We operationalize this assumption with an Aligned Sparse Autoencoder (SAE) that encourages energy consistency during training while preserving reconstruction. We find that this inductive bias changes the SAE solution without harming reconstruction, giving us a representation that serves as a tool for geometric analysis. Sanity checks on controlled data with known ground truth confirm that alignment improves when Iso-Energy holds and remains neutral when it does not. Applied to foundational VLMs, our framework reveals a clear structure with practical consequences: (i) sparse bimodal atoms carry the entire cross-modal alignment signal; (ii) unimodal atoms act as modality-specific biases and fully explain the modality gap; (iii) removing unimodal atoms collapses the gap without harming performance; (iv) restricting vector arithmetic to the bimodal subspace yields in-distribution edits and improved retrieval. These findings suggest that the right inductive bias can both preserve model fidelity and render the latent geometry interpretable and actionable.
title Cross-Modal Redundancy and the Geometry of Vision-Language Embeddings
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2602.06218