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Main Authors: Zhang, Baoquan, Yu, Zhehao, Zhang, Lisai, Lin, Kenghong, Chen, Tianran, Sun, Yuxi, Ye, Yunming, He, Yao
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.08589
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author Zhang, Baoquan
Yu, Zhehao
Zhang, Lisai
Lin, Kenghong
Chen, Tianran
Sun, Yuxi
Ye, Yunming
He, Yao
author_facet Zhang, Baoquan
Yu, Zhehao
Zhang, Lisai
Lin, Kenghong
Chen, Tianran
Sun, Yuxi
Ye, Yunming
He, Yao
contents Parameter Efficient Fine-Tuning (PEFT) is a key technique for adapting a large pretrained model to downstream tasks by fine-tuning only a small number of parameters. Recent methods based on Fourier transforms have further reduced the fine-tuned parameters scale by only fine-tuning a few spectral coefficients. Its basic assumption is that the weight change δW is a spatial-domain matrix with a sparse spectrum. However, in this paper, we observe that the spectrum of weight change is not sparse, but instead distributed like power-uniform. This fact implies that fine-tuning only a few spectral coefficients is insufficient to accurately model the weight change with uniform spectrum. To address this issue, we propose to seek an invertible transformation that can transform a latent spatial-domain matrix with sparse spectrum to the weight change, and then perform PEFT on such sparse spectrum domain with few spectral coefficients, called S2FT. To seek such transformation, we first pre-estimate a coarse weight change as a prior. Then, inspired by that sparse spectrum often correspond to locally smooth spatial structures, we regard this transformation as a row and column rearrangement operation on the pre-estimated weight change that smooth spatial structures while keep the structure information of neurons. Finally, we propose to solve the rearrangement search problem in a simple nearest neighbor search manner, thereby obtaining the invertible transformation. Extensive results show our S2FT achieves superior performance by only using 0.08% training parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08589
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle S2FT: Parameter-Efficient Fine-Tuning in Sparse Spectrum Domain
Zhang, Baoquan
Yu, Zhehao
Zhang, Lisai
Lin, Kenghong
Chen, Tianran
Sun, Yuxi
Ye, Yunming
He, Yao
Computer Vision and Pattern Recognition
Parameter Efficient Fine-Tuning (PEFT) is a key technique for adapting a large pretrained model to downstream tasks by fine-tuning only a small number of parameters. Recent methods based on Fourier transforms have further reduced the fine-tuned parameters scale by only fine-tuning a few spectral coefficients. Its basic assumption is that the weight change δW is a spatial-domain matrix with a sparse spectrum. However, in this paper, we observe that the spectrum of weight change is not sparse, but instead distributed like power-uniform. This fact implies that fine-tuning only a few spectral coefficients is insufficient to accurately model the weight change with uniform spectrum. To address this issue, we propose to seek an invertible transformation that can transform a latent spatial-domain matrix with sparse spectrum to the weight change, and then perform PEFT on such sparse spectrum domain with few spectral coefficients, called S2FT. To seek such transformation, we first pre-estimate a coarse weight change as a prior. Then, inspired by that sparse spectrum often correspond to locally smooth spatial structures, we regard this transformation as a row and column rearrangement operation on the pre-estimated weight change that smooth spatial structures while keep the structure information of neurons. Finally, we propose to solve the rearrangement search problem in a simple nearest neighbor search manner, thereby obtaining the invertible transformation. Extensive results show our S2FT achieves superior performance by only using 0.08% training parameters.
title S2FT: Parameter-Efficient Fine-Tuning in Sparse Spectrum Domain
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.08589