Pre-training CLIP against Data Poisoning with Optimal Transport-based Matching and Alignment

Fuente: arXiv
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Main Authors: Zhang, Tong, Gao, Kuofeng, Bai, Jiawang, Zhang, Leo Yu, Yin, Xin, Wang, Zonghui, Ji, Shouling, Chen, Wenzhi
Format: Preprint
Published: 2025
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author Zhang, Tong
Gao, Kuofeng
Bai, Jiawang
Zhang, Leo Yu
Yin, Xin
Wang, Zonghui
Ji, Shouling
Chen, Wenzhi
author_facet Zhang, Tong
Gao, Kuofeng
Bai, Jiawang
Zhang, Leo Yu
Yin, Xin
Wang, Zonghui
Ji, Shouling
Chen, Wenzhi
contents Recent studies have shown that Contrastive Language-Image Pre-training (CLIP) models are threatened by targeted data poisoning and backdoor attacks due to massive training image-caption pairs crawled from the Internet. Previous defense methods correct poisoned image-caption pairs by matching a new caption for each image. However, the matching process relies solely on the global representations of images and captions, overlooking fine-grained features of visual and textual features. It may introduce incorrect image-caption pairs and harm the CLIP pre-training. To address their limitations, we propose an Optimal Transport-based framework to reconstruct image-caption pairs, named OTCCLIP. We propose a new optimal transport-based distance measure between fine-grained visual and textual feature sets and re-assign new captions based on the proposed optimal transport distance. Additionally, to further reduce the negative impact of mismatched pairs, we encourage the inter- and intra-modality fine-grained alignment by employing optimal transport-based objective functions. Our experiments demonstrate that OTCCLIP can successfully decrease the attack success rates of poisoning attacks. Also, compared to previous methods, OTCCLIP significantly improves CLIP's zero-shot and linear probing performance trained on poisoned datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2509_18717
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pre-training CLIP against Data Poisoning with Optimal Transport-based Matching and Alignment
Zhang, Tong
Gao, Kuofeng
Bai, Jiawang
Zhang, Leo Yu
Yin, Xin
Wang, Zonghui
Ji, Shouling
Chen, Wenzhi
Computer Vision and Pattern Recognition
Multimedia
Recent studies have shown that Contrastive Language-Image Pre-training (CLIP) models are threatened by targeted data poisoning and backdoor attacks due to massive training image-caption pairs crawled from the Internet. Previous defense methods correct poisoned image-caption pairs by matching a new caption for each image. However, the matching process relies solely on the global representations of images and captions, overlooking fine-grained features of visual and textual features. It may introduce incorrect image-caption pairs and harm the CLIP pre-training. To address their limitations, we propose an Optimal Transport-based framework to reconstruct image-caption pairs, named OTCCLIP. We propose a new optimal transport-based distance measure between fine-grained visual and textual feature sets and re-assign new captions based on the proposed optimal transport distance. Additionally, to further reduce the negative impact of mismatched pairs, we encourage the inter- and intra-modality fine-grained alignment by employing optimal transport-based objective functions. Our experiments demonstrate that OTCCLIP can successfully decrease the attack success rates of poisoning attacks. Also, compared to previous methods, OTCCLIP significantly improves CLIP's zero-shot and linear probing performance trained on poisoned datasets.
title Pre-training CLIP against Data Poisoning with Optimal Transport-based Matching and Alignment
topic Computer Vision and Pattern Recognition
Multimedia
url https://arxiv.org/abs/2509.18717