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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.
According to the distribution of wavelet coefficients of signal and noise on different decomposition scales, a new method to eliminate speckle noise of Synthetic Aperture Radar (SAR) image by wavelet packet transform (WPT) is proposed.According to the optimal decomposition on orthogonal wavelet basis, In addition, the cost function is decomposed to deal with each leaf node subspace except the approximate subspace in the decomposed wavelet tree adaptively.The leaf node threshold is calculated by the variance of the estimated variance of the noise of each leaf node and the whole image. Experimental results show that this method can effectively reduce the speckle noise while preserving the edge details.