近年来,小波滤波得到了很大的发展,已经渗透到了许多理论与应用领域。但作为一种新的信号滤波方法,尚存在不少有待解决的问题。本文基于静态小波变换(stationary wavelet transform,SWT),将小波系数间的相关性应用于滤波,系统探讨了SWT的快速实现和滤波算法的设计问题,并进行了大量的仿真分析。论文的主要工作如下:
1.针对SWT的双通道滤波器组算法存在计算量大等问题,深入研究了SWT的提升实现算法。该算法利用滤波器与采样算子的等效易位关系,将SWT分解为有限步交替的(对偶)提升步骤。而后采用Laurent多项式的Euclidean分解原理进行复杂度分析,得出结论:与传统SWT实现算法相比,可减少近一半计算量。最后通过构造(对偶)提升算子来提高小波基的(对偶)消失矩。
2.为实现信号和噪声的有效分离,结合尺度内和尺度间相关性,构造了一种基于小波域混合相关性的显著性函数——锥形影响域(cone of influence,COI)相邻尺度积系数。在此基础上,对小波系数幅值、原始相邻尺度积系数及COI相邻尺度积系数的信噪分离特性进行了深入...
【英文摘要】
Recently, wavelet denoising has been widely used in many fields of theory and application. As a new denoising method, there still exist some issues. In this dissertation, based on the stationary wavelet transform (SWT), different dependencies among wavelet coefficients are studied in denoising. The fast algorithm of SWT and new wavelet denoising methods are developed and proposed respectively. The main contributions are as follows:
1. The factorizing algorithm of SWT using lifting scheme is imple...