WaRA: Wavelet Low Rank Adaptation

Fuente: arXiv
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Main Authors: Heidari, Moein, Huang, Yijin, Medghalchi, Yasamin, Rafiee, Alireza, Tam, Roger, Hacihaliloglu, Ilker
Format: Preprint
Published: 2025
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author Heidari, Moein
Huang, Yijin
Medghalchi, Yasamin
Rafiee, Alireza
Tam, Roger
Hacihaliloglu, Ilker
author_facet Heidari, Moein
Huang, Yijin
Medghalchi, Yasamin
Rafiee, Alireza
Tam, Roger
Hacihaliloglu, Ilker
contents Adapting large pretrained vision models to medical image classification is often limited by memory, computation, and task-specific specializations. Parameter-efficient fine-tuning (PEFT) methods like LoRA reduce this cost by learning low-rank updates, but operating directly in feature space can struggle to capture the localized, multi-scale features common in medical imaging. We propose WaRA, a wavelet-structured adaptation module that performs low-rank adaptation in a wavelet domain. WaRA reshapes patch tokens into a spatial grid, applies a fixed discrete wavelet transform, updates subband coefficients using a shared low-rank adapter, and reconstructs the additive update through an inverse wavelet transform. This design provides a compact trainable interface while biasing the update toward both coarse structure and fine detail. For extremely low-resource settings, we introduce Tiny-WaRA, which further reduces trainable parameters by learning only a small set of coefficients in a fixed basis derived from the pretrained weights through a truncated SVD. Experiments on medical image classification across four modalities and datasets demonstrate that WaRA consistently improves performance over strong PEFT baselines, while retaining a favorable efficiency profile. Our code is publicly available at~\href{https://github.com/moeinheidari7829/WaRA}{\textcolor{magenta}{GitHub}}.
format Preprint
id arxiv_https___arxiv_org_abs_2506_24092
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle WaRA: Wavelet Low Rank Adaptation
Heidari, Moein
Huang, Yijin
Medghalchi, Yasamin
Rafiee, Alireza
Tam, Roger
Hacihaliloglu, Ilker
Computer Vision and Pattern Recognition
Image and Video Processing
Adapting large pretrained vision models to medical image classification is often limited by memory, computation, and task-specific specializations. Parameter-efficient fine-tuning (PEFT) methods like LoRA reduce this cost by learning low-rank updates, but operating directly in feature space can struggle to capture the localized, multi-scale features common in medical imaging. We propose WaRA, a wavelet-structured adaptation module that performs low-rank adaptation in a wavelet domain. WaRA reshapes patch tokens into a spatial grid, applies a fixed discrete wavelet transform, updates subband coefficients using a shared low-rank adapter, and reconstructs the additive update through an inverse wavelet transform. This design provides a compact trainable interface while biasing the update toward both coarse structure and fine detail. For extremely low-resource settings, we introduce Tiny-WaRA, which further reduces trainable parameters by learning only a small set of coefficients in a fixed basis derived from the pretrained weights through a truncated SVD. Experiments on medical image classification across four modalities and datasets demonstrate that WaRA consistently improves performance over strong PEFT baselines, while retaining a favorable efficiency profile. Our code is publicly available at~\href{https://github.com/moeinheidari7829/WaRA}{\textcolor{magenta}{GitHub}}.
title WaRA: Wavelet Low Rank Adaptation
topic Computer Vision and Pattern Recognition
Image and Video Processing
url https://arxiv.org/abs/2506.24092