From Easy to Hard: Building a Shortcut for Differentially Private Image Synthesis

Fuente: arXiv
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Main Authors: Li, Kecen, Gong, Chen, Li, Xiaochen, Zhao, Yuzhong, Hou, Xinwen, Wang, Tianhao
Format: Preprint
Published: 2025
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author Li, Kecen
Gong, Chen
Li, Xiaochen
Zhao, Yuzhong
Hou, Xinwen
Wang, Tianhao
author_facet Li, Kecen
Gong, Chen
Li, Xiaochen
Zhao, Yuzhong
Hou, Xinwen
Wang, Tianhao
contents Differentially private (DP) image synthesis aims to generate synthetic images from a sensitive dataset, alleviating the privacy leakage concerns of organizations sharing and utilizing synthetic images. Although previous methods have significantly progressed, especially in training diffusion models on sensitive images with DP Stochastic Gradient Descent (DP-SGD), they still suffer from unsatisfactory performance. In this work, inspired by curriculum learning, we propose a two-stage DP image synthesis framework, where diffusion models learn to generate DP synthetic images from easy to hard. Unlike existing methods that directly use DP-SGD to train diffusion models, we propose an easy stage in the beginning, where diffusion models learn simple features of the sensitive images. To facilitate this easy stage, we propose to use `central images', simply aggregations of random samples of the sensitive dataset. Intuitively, although those central images do not show details, they demonstrate useful characteristics of all images and only incur minimal privacy costs, thus helping early-phase model training. We conduct experiments to present that on the average of four investigated image datasets, the fidelity and utility metrics of our synthetic images are 33.1% and 2.1% better than the state-of-the-art method.
format Preprint
id arxiv_https___arxiv_org_abs_2504_01395
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle From Easy to Hard: Building a Shortcut for Differentially Private Image Synthesis
Li, Kecen
Gong, Chen
Li, Xiaochen
Zhao, Yuzhong
Hou, Xinwen
Wang, Tianhao
Cryptography and Security
Artificial Intelligence
Differentially private (DP) image synthesis aims to generate synthetic images from a sensitive dataset, alleviating the privacy leakage concerns of organizations sharing and utilizing synthetic images. Although previous methods have significantly progressed, especially in training diffusion models on sensitive images with DP Stochastic Gradient Descent (DP-SGD), they still suffer from unsatisfactory performance. In this work, inspired by curriculum learning, we propose a two-stage DP image synthesis framework, where diffusion models learn to generate DP synthetic images from easy to hard. Unlike existing methods that directly use DP-SGD to train diffusion models, we propose an easy stage in the beginning, where diffusion models learn simple features of the sensitive images. To facilitate this easy stage, we propose to use `central images', simply aggregations of random samples of the sensitive dataset. Intuitively, although those central images do not show details, they demonstrate useful characteristics of all images and only incur minimal privacy costs, thus helping early-phase model training. We conduct experiments to present that on the average of four investigated image datasets, the fidelity and utility metrics of our synthetic images are 33.1% and 2.1% better than the state-of-the-art method.
title From Easy to Hard: Building a Shortcut for Differentially Private Image Synthesis
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2504.01395