提出新型图傅里叶变换,可同时调节阶数与旋转角度,提升信号去噪和重建效果。
Rotation-Parameterized Graph Fractional Fourier Transform: Definition, Properties, and Optimal Filtering
- 将分数阶与旋转参数统一,构造保持零角退化特性的基变换矩阵
- 在真实信号、图像和点云上实现更优的降噪精度与特征保留能力
- 适合需要灵活谱分析的图信号处理任务,如点云去噪或图像恢复
图谱表示是图信号处理的基础,为结构化数据提供严谨的分析框架。图分数阶傅里叶变换(GFRFT)通过分数阶参数扩展了图傅里叶变换(GFT),实现灵活且数学一致的谱分析。角图傅里叶变换(AGFT)引入旋转控制以调整GFT特征向量;然而现有方法在零角时无法精确退化为GFT,削弱理论一致性与可解释性。为解决上述互补缺陷——即GFRFT缺乏基于旋转的基控制、AGFT存在零角退化缺陷——本文提出旋转参数化图分数阶傅里叶变换(RP-GFRFT),统一分数阶与旋转参数化的谱分析。构建保持退化性质的旋转矩阵族,确保零角时精确还原为GFT。提出两种变体I-RP-GFRFT与II-RP-GFRFT,理论分析证实其酉性、可逆性、退化行为及平滑参数依赖性。联合优化分数阶与旋转角,实现自适应图谱滤波。在真实信号、图像和点云上的实验表明,RP-GFRFT在去噪精度、重建质量与特征保留方面均优于GFRFT、AGFT及代表性滤波基线。
原文摘要 · Abstract (English)
Graph spectral representations are fundamental in graph signal processing, providing a rigorous frameworkforanalyzing graph-structured data. The graph fractional Fourier transform (GFRFT) extends the graph Fourier transform (GFT) through a fractional-order parameter, enabling flexible spectral analysis with mathematical consistency. The angular graph Fourier transform (AGFT) further introduces angular control by rotating GFT eigenvectors; however, existing constructions may fail to reduce exactly to the GFT at zero angle, weakening theoretical consistency and interpretability. To address these complementary limitations, namely the lack of rotation-based basis control in GFRFT and the defective zero-angle degeneracy of AGFT, this paper proposes the rotation-parameterized graph fractional Fourier transform (RP-GFRFT), which unifies fractional order and rotation-parameterized spectral analysis. A degeneracy preserving rotation matrix family is constructed to guarantee exact GFT reduction at zero angle. TwoRP-GFRFTvariants,I-RP-GFRFTandII-RP-GFRFT,arethenformulated, with theoretical analyses confirming their unitarity, invertibility, reduction behavior, and smooth parameter dependence. The fractional order and rotation angle are jointly optimized for adaptive graph spectral filtering. Experiments on real-world signals, images, and point clouds demonstrate that RP-GFRFT improves denoising accuracy, reconstruction quality, and feature preservation over GFRFT, AGFT, and representative filtering baselines.
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