Theoretical Refinement of CLIP by Utilizing Linear Structure of Optimal Similarity

Fuente: arXiv
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Autores principales: Yoshida, Naoki, Hayakawa, Satoshi, Takida, Yuhta, Uesaka, Toshimitsu, Wakaki, Hiromi, Mitsufuji, Yuki
Formato: Preprint
Publicado: 2025
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author Yoshida, Naoki
Hayakawa, Satoshi
Takida, Yuhta
Uesaka, Toshimitsu
Wakaki, Hiromi
Mitsufuji, Yuki
author_facet Yoshida, Naoki
Hayakawa, Satoshi
Takida, Yuhta
Uesaka, Toshimitsu
Wakaki, Hiromi
Mitsufuji, Yuki
contents In this study, we propose an enhancement to the similarity computation mechanism in multi-modal contrastive pretraining frameworks such as CLIP. Prior theoretical research has demonstrated that the optimal similarity metrics between paired modalities should correspond to the pointwise mutual information (PMI) between the two modalities. However, the current implementations of CLIP and its variants fail to fully utilize the underlying linear structure of PMI. We therefore propose KME-CLIP, which leverages this structure through the inner product in a reproducing kernel Hilbert space. We theoretically prove that our method can approximate PMI with arbitrary accuracy and empirically demonstrate that our approach overall outperforms the standard CLIP formulation across several retrieval and classification tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15508
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Theoretical Refinement of CLIP by Utilizing Linear Structure of Optimal Similarity
Yoshida, Naoki
Hayakawa, Satoshi
Takida, Yuhta
Uesaka, Toshimitsu
Wakaki, Hiromi
Mitsufuji, Yuki
Machine Learning
Numerical Analysis
In this study, we propose an enhancement to the similarity computation mechanism in multi-modal contrastive pretraining frameworks such as CLIP. Prior theoretical research has demonstrated that the optimal similarity metrics between paired modalities should correspond to the pointwise mutual information (PMI) between the two modalities. However, the current implementations of CLIP and its variants fail to fully utilize the underlying linear structure of PMI. We therefore propose KME-CLIP, which leverages this structure through the inner product in a reproducing kernel Hilbert space. We theoretically prove that our method can approximate PMI with arbitrary accuracy and empirically demonstrate that our approach overall outperforms the standard CLIP formulation across several retrieval and classification tasks.
title Theoretical Refinement of CLIP by Utilizing Linear Structure of Optimal Similarity
topic Machine Learning
Numerical Analysis
url https://arxiv.org/abs/2510.15508