基于斑点噪声的拖尾Rayleigh分布的合成孔径雷达图像最大后验概率降噪  

Maximum a posteriori filtering for synthetic aperture radar images based on heavy-tailed Rayleigh distribution of speckle

作　　者：孙增国[1] 韩崇昭[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《物理学报》2007年第8期4565-4570,共6页Acta Physica Sinica

基　　金：国家重点基础研究发展规划(批准号:2001CB309405);国家自然科学基金(批准号:60574033)资助的课题.~~

摘　　要：为了反映合成孔径雷达图像中斑点噪声尖峰厚尾的统计特征,使用拖尾Rayleigh分布来描述斑点噪声.基于Gamma先验分布和斑点噪声的拖尾Rayleigh分布,推导出了合成孔径雷达图像的最大后验概率滤波方程,并给出了它在特定特征参数时的解析形式.使用Mellin变换从观察图像估计拖尾Rayleigh分布的未知参数.给出了在斑点噪声的拖尾Rayleigh分布下的最大后验概率降噪试验和量化指标.为了消除滑动窗大小和噪声强度对降噪结果的影响,给出了降噪能力随滑动窗大小和噪声方差的动态变化关系.结果表明,拖尾Rayleigh分布尖峰厚尾的特征符合斑点噪声的真实统计特性,因此与Rayleigh分布以及Kuan滤波相比,基于斑点噪声的拖尾Rayleigh分布的最大后验概率滤波具有较强的降噪能力.In order to reflect the statistics of high peak and heavy tail, speckle in synthetic aperture radar images is modeled as heavy- tailed Rayleigh distribution. First, based on Gamma prior distribution and heavy-tailed Rayleigh distribution of speckle, the maximum a pesteriori filtering equation is proposed and its analytical form is provided in given characteristic parameter. Second, parameters of heavy-tailed Rayleigh distribution are estimated from the observed image using Mellin transformation. Last, maximum a pesteriori de-speckling experiments and their quantitative measures are given. In order to eliminate the influence of window size and noise intensity on de-speckling results, dynamic relations of the de-speckling capability to noise variance and window size are suggested respectively. Results demonstrate that the heavy-tailed Rayleigh distribution accords with the real statistics of speckle, so the maximum a pesteriori filter in heavy-tailed Rayleigh distribution of speckle has higher capability of noise reduction compared to the one in Rayleigh distribution of speckle and the Kuan filter.

关 键 词：斑点噪声 拖尾Rayleigh分布 最大后验概率降噪 Mellin变换 

分 类 号：TN957.52[电子电信—信号与信息处理]