提出频域自适应方法,提升跨域少样本学习的泛化能力。
FAD: Frequency Adaptation and Diversion for Cross-domain Few-shot Learning
- 将特征转换到频域,分高低频带分别适应
- 在Meta-Dataset上显著优于现有方法
- 适合需要强泛化能力的跨域少样本场景
跨域少样本学习(CD-FSL)要求模型在显著分布偏移下,仅用少量标注样本实现良好泛化。现有方法虽通过轻量级任务适配模块提升适应性,但仅在空间域操作,忽略频域差异。我们观察到,跨域空间相似的图像在频谱表示上可能差异显著,低频与高频分别捕捉粗粒度和细粒度语义信息。因此,统一的空间适应可能遗漏关键频域特征,限制泛化能力。为此,提出频率自适应与分流(FAD)框架,显式建模并调控频域成分。核心为频域分流适配器,利用离散傅里叶变换(DFT)将中间特征转至频域,通过径向掩码划分低、中、高频带,并使用逆傅里叶变换(IDFT)重构。各频带由对应卷积分支独立适配,卷积核大小按频带尺度定制,实现频域解耦的精准适配。在Meta-Dataset基准上的大量实验表明,FAD在已见与未见域上均持续优于当前最优方法,验证了频域表征与带间适配对提升CD-FSL泛化的有效性。
原文摘要 · Abstract (English)
Cross-domain few-shot learning (CD-FSL) requires models to generalize from limited labeled samples under significant distribution shifts. While recent methods enhance adaptability through lightweight task-specific modules, they operate solely in the spatial domain and overlook frequency-specific variations that are often critical for robust transfer. We observe that spatially similar images across domains can differ substantially in their spectral representations, with low and high frequencies capturing complementary semantic information at coarse and fine levels. This indicates that uniform spatial adaptation may overlook these spectral distinctions, thus constraining generalization. To address this, we introduce Frequency Adaptation and Diversion (FAD), a frequency-aware framework that explicitly models and modulates spectral components. At its core is the Frequency Diversion Adapter, which transforms intermediate features into the frequency domain using the discrete Fourier transform (DFT), partitions them into low, mid, and high-frequency bands via radial masks, and reconstructs each band using inverse DFT (IDFT). Each frequency band is then adapted using a dedicated convolutional branch with a kernel size tailored to its spectral scale, enabling targeted and disentangled adaptation across frequencies. Extensive experiments on the Meta-Dataset benchmark demonstrate that FAD consistently outperforms state-of-the-art methods on both seen and unseen domains, validating the utility of frequency-domain representations and band-wise adaptation for improving generalization in CD-FSL.
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