SafeText: Safe Text-to-image Models via Aligning the Text Encoder

Fuente: arXiv
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Auteurs principaux: Hu, Yuepeng, Jiang, Zhengyuan, Gong, Neil Zhenqiang
Format: Preprint
Publié: 2025
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author Hu, Yuepeng
Jiang, Zhengyuan
Gong, Neil Zhenqiang
author_facet Hu, Yuepeng
Jiang, Zhengyuan
Gong, Neil Zhenqiang
contents Text-to-image models can generate harmful images when presented with unsafe prompts, posing significant safety and societal risks. Alignment methods aim to modify these models to ensure they generate only non-harmful images, even when exposed to unsafe prompts. A typical text-to-image model comprises two main components: 1) a text encoder and 2) a diffusion module. Existing alignment methods mainly focus on modifying the diffusion module to prevent harmful image generation. However, this often significantly impacts the model's behavior for safe prompts, causing substantial quality degradation of generated images. In this work, we propose SafeText, a novel alignment method that fine-tunes the text encoder rather than the diffusion module. By adjusting the text encoder, SafeText significantly alters the embedding vectors for unsafe prompts, while minimally affecting those for safe prompts. As a result, the diffusion module generates non-harmful images for unsafe prompts while preserving the quality of images for safe prompts. We evaluate SafeText on multiple datasets of safe and unsafe prompts, including those generated through jailbreak attacks. Our results show that SafeText effectively prevents harmful image generation with minor impact on the images for safe prompts, and SafeText outperforms six existing alignment methods. We will publish our code and data after paper acceptance.
format Preprint
id arxiv_https___arxiv_org_abs_2502_20623
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SafeText: Safe Text-to-image Models via Aligning the Text Encoder
Hu, Yuepeng
Jiang, Zhengyuan
Gong, Neil Zhenqiang
Cryptography and Security
Computer Vision and Pattern Recognition
Text-to-image models can generate harmful images when presented with unsafe prompts, posing significant safety and societal risks. Alignment methods aim to modify these models to ensure they generate only non-harmful images, even when exposed to unsafe prompts. A typical text-to-image model comprises two main components: 1) a text encoder and 2) a diffusion module. Existing alignment methods mainly focus on modifying the diffusion module to prevent harmful image generation. However, this often significantly impacts the model's behavior for safe prompts, causing substantial quality degradation of generated images. In this work, we propose SafeText, a novel alignment method that fine-tunes the text encoder rather than the diffusion module. By adjusting the text encoder, SafeText significantly alters the embedding vectors for unsafe prompts, while minimally affecting those for safe prompts. As a result, the diffusion module generates non-harmful images for unsafe prompts while preserving the quality of images for safe prompts. We evaluate SafeText on multiple datasets of safe and unsafe prompts, including those generated through jailbreak attacks. Our results show that SafeText effectively prevents harmful image generation with minor impact on the images for safe prompts, and SafeText outperforms six existing alignment methods. We will publish our code and data after paper acceptance.
title SafeText: Safe Text-to-image Models via Aligning the Text Encoder
topic Cryptography and Security
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2502.20623