LCUDiff: Latent Capacity Upgrade Diffusion for Faithful Human Body Restoration

Fuente: arXiv
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Autores principales: Gong, Jue, Zhou, Zihan, Wang, Jingkai, Li, Shu, Liu, Libo, Lan, Jianliang, Zhang, Yulun
Formato: Preprint
Publicado: 2026
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author Gong, Jue
Zhou, Zihan
Wang, Jingkai
Li, Shu
Liu, Libo
Lan, Jianliang
Zhang, Yulun
author_facet Gong, Jue
Zhou, Zihan
Wang, Jingkai
Li, Shu
Liu, Libo
Lan, Jianliang
Zhang, Yulun
contents Existing methods for restoring degraded human-centric images often struggle with insufficient fidelity, particularly in human body restoration (HBR). Recent diffusion-based restoration methods commonly adapt pre-trained text-to-image diffusion models, where the variational autoencoder (VAE) can significantly bottleneck restoration fidelity. We propose LCUDiff, a stable one-step framework that upgrades a pre-trained latent diffusion model from the 4-channel latent space to the 16-channel latent space. For VAE fine-tuning, channel splitting distillation (CSD) is used to keep the first four channels aligned with pre-trained priors while allocating the additional channels to effectively encode high-frequency details. We further design prior-preserving adaptation (PPA) to smoothly bridge the mismatch between 4-channel diffusion backbones and the higher-dimensional 16-channel latent. In addition, we propose a decoder router (DeR) for per-sample decoder routing using restoration-quality score annotations, which improves visual quality across diverse conditions. Experiments on synthetic and real-world datasets show competitive results with higher fidelity and fewer artifacts under mild degradations, while preserving one-step efficiency. The code and model will be at https://github.com/gobunu/LCUDiff.
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle LCUDiff: Latent Capacity Upgrade Diffusion for Faithful Human Body Restoration
Gong, Jue
Zhou, Zihan
Wang, Jingkai
Li, Shu
Liu, Libo
Lan, Jianliang
Zhang, Yulun
Computer Vision and Pattern Recognition
Existing methods for restoring degraded human-centric images often struggle with insufficient fidelity, particularly in human body restoration (HBR). Recent diffusion-based restoration methods commonly adapt pre-trained text-to-image diffusion models, where the variational autoencoder (VAE) can significantly bottleneck restoration fidelity. We propose LCUDiff, a stable one-step framework that upgrades a pre-trained latent diffusion model from the 4-channel latent space to the 16-channel latent space. For VAE fine-tuning, channel splitting distillation (CSD) is used to keep the first four channels aligned with pre-trained priors while allocating the additional channels to effectively encode high-frequency details. We further design prior-preserving adaptation (PPA) to smoothly bridge the mismatch between 4-channel diffusion backbones and the higher-dimensional 16-channel latent. In addition, we propose a decoder router (DeR) for per-sample decoder routing using restoration-quality score annotations, which improves visual quality across diverse conditions. Experiments on synthetic and real-world datasets show competitive results with higher fidelity and fewer artifacts under mild degradations, while preserving one-step efficiency. The code and model will be at https://github.com/gobunu/LCUDiff.
title LCUDiff: Latent Capacity Upgrade Diffusion for Faithful Human Body Restoration
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.04406