应用小波包变换的斑点噪声抑制方法

摘要

根据信号和噪声的小波系数在不同分解尺度上的分布,提出应用小波包变换(WPT)消除合成孔径雷达(SAR)图像斑点噪声的新方法.根据在正交小波基上的最优分解,通过叠加代价函数,对分解得到的小波包树中除近似子空间以外每个叶节点子空间以自适应的方式进行处理.通过每一叶节点以及整个图像的噪声的估计方差变化计算叶节点阈值.实验结果表明,该方法能有效地减少斑点噪声,同时保存边缘细节.%A novel approach of speckle noise reduction is put forward according to the distributions of signal and noise under different scales of Synthetic Aperture Radar (SAR) images based on Wavelet Packet Transform (WPT). Based on optimal decomposition on orthogonal wavelet basis via additive cost function and, the thresholding on each leaf subband of the resultant wavelet packet tree except the approximate leaf subband is processed in adaptive manner. The threshold of each leaf is calculated through the variance of each and the estimated noise variance of the entire image. Experimental results show that this method can effectively reduce speckle noise, while preserving edge sharpness.