Stay Fair! Ensuring Group Fairness in Diffusion Models Across Guidance Scales

Fuente: arXiv
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Main Authors: Kim, Myeongsoo, Kim, Eunji, Chae, Minwoo, Mo, Sangwoo
Format: Preprint
Published: 2026
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author Kim, Myeongsoo
Kim, Eunji
Chae, Minwoo
Mo, Sangwoo
author_facet Kim, Myeongsoo
Kim, Eunji
Chae, Minwoo
Mo, Sangwoo
contents Diffusion models steer conditional generation with a tunable guidance scale to trade off prompt alignment and diversity. However, existing debiasing techniques are optimized for a single scale, degrading fairness when users adjust this parameter. We trace this behavior to a previously overlooked source by decomposing total bias into two components: a model bias and a guidance bias. While prior work primarily targets the former, we show that the guidance bias grows monotonically with the guidance scale, eventually dominating the high-guidance regimes users prefer. To address this, we extend Strong Demographic Parity to guidance and derive a condition under which the target distribution retains its group ratio across guidance scales. We propose StayFair, which leverages this condition to design fair guidance algorithms in both regimes. For classifier guidance, it equalizes the classifier's output distributions across groups; for classifier-free guidance, it shifts the null embedding by a prompt-dependent offset. Because StayFair modifies only the guidance step, it is orthogonal to model debiasing and can be layered onto existing fair diffusion models to extend their fairness across guidance scales. Across class-conditional and text-to-image generation, StayFair decouples fairness from the guidance scale without sacrificing image quality.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28036
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stay Fair! Ensuring Group Fairness in Diffusion Models Across Guidance Scales
Kim, Myeongsoo
Kim, Eunji
Chae, Minwoo
Mo, Sangwoo
Computer Vision and Pattern Recognition
Machine Learning
Diffusion models steer conditional generation with a tunable guidance scale to trade off prompt alignment and diversity. However, existing debiasing techniques are optimized for a single scale, degrading fairness when users adjust this parameter. We trace this behavior to a previously overlooked source by decomposing total bias into two components: a model bias and a guidance bias. While prior work primarily targets the former, we show that the guidance bias grows monotonically with the guidance scale, eventually dominating the high-guidance regimes users prefer. To address this, we extend Strong Demographic Parity to guidance and derive a condition under which the target distribution retains its group ratio across guidance scales. We propose StayFair, which leverages this condition to design fair guidance algorithms in both regimes. For classifier guidance, it equalizes the classifier's output distributions across groups; for classifier-free guidance, it shifts the null embedding by a prompt-dependent offset. Because StayFair modifies only the guidance step, it is orthogonal to model debiasing and can be layered onto existing fair diffusion models to extend their fairness across guidance scales. Across class-conditional and text-to-image generation, StayFair decouples fairness from the guidance scale without sacrificing image quality.
title Stay Fair! Ensuring Group Fairness in Diffusion Models Across Guidance Scales
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2605.28036