Sparsity Outperforms Low-Rank Projections in Few-Shot Adaptation

Fuente: arXiv
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Auteurs principaux: Mrabah, Nairouz, Richet, Nicolas, Ayed, Ismail Ben, Granger, Éric
Format: Preprint
Publié: 2025
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author Mrabah, Nairouz
Richet, Nicolas
Ayed, Ismail Ben
Granger, Éric
author_facet Mrabah, Nairouz
Richet, Nicolas
Ayed, Ismail Ben
Granger, Éric
contents Adapting Vision-Language Models (VLMs) to new domains with few labeled samples remains a significant challenge due to severe overfitting and computational constraints. State-of-the-art solutions, such as low-rank reparameterization, mitigate these issues but often struggle with generalization and require extensive hyperparameter tuning. In this paper, a novel Sparse Optimization (SO) framework is proposed. Unlike low-rank approaches that typically constrain updates to a fixed subspace, our SO method leverages high sparsity to dynamically adjust very few parameters. We introduce two key paradigms. First, we advocate for \textit{local sparsity and global density}, which updates a minimal subset of parameters per iteration while maintaining overall model expressiveness. As a second paradigm, we advocate for \textit{local randomness and global importance}, which sparsifies the gradient using random selection while pruning the first moment based on importance. This combination significantly mitigates overfitting and ensures stable adaptation in low-data regimes. Extensive experiments on 11 diverse datasets show that SO achieves state-of-the-art few-shot adaptation performance while reducing memory overhead.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12436
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sparsity Outperforms Low-Rank Projections in Few-Shot Adaptation
Mrabah, Nairouz
Richet, Nicolas
Ayed, Ismail Ben
Granger, Éric
Computer Vision and Pattern Recognition
Artificial Intelligence
Adapting Vision-Language Models (VLMs) to new domains with few labeled samples remains a significant challenge due to severe overfitting and computational constraints. State-of-the-art solutions, such as low-rank reparameterization, mitigate these issues but often struggle with generalization and require extensive hyperparameter tuning. In this paper, a novel Sparse Optimization (SO) framework is proposed. Unlike low-rank approaches that typically constrain updates to a fixed subspace, our SO method leverages high sparsity to dynamically adjust very few parameters. We introduce two key paradigms. First, we advocate for \textit{local sparsity and global density}, which updates a minimal subset of parameters per iteration while maintaining overall model expressiveness. As a second paradigm, we advocate for \textit{local randomness and global importance}, which sparsifies the gradient using random selection while pruning the first moment based on importance. This combination significantly mitigates overfitting and ensures stable adaptation in low-data regimes. Extensive experiments on 11 diverse datasets show that SO achieves state-of-the-art few-shot adaptation performance while reducing memory overhead.
title Sparsity Outperforms Low-Rank Projections in Few-Shot Adaptation
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2504.12436