摘要
为有效抑制激光主动成像中的散斑噪声以及减少运算耗时,提出一种基于信号子空间谱域约束的散斑去噪方法。使用同态变换将乘性噪声变为加性噪声,对含噪图像进行奇异值分解并估计信号子空间的维数,根据该维数对含噪图像的协方差矩阵进行特征值分解,利用噪声子空间的特征值估计噪声的方差。根据信号子空间的特征向量计算出滤波估计矩阵,并与含噪图像卷积,做同态逆变换,得到降噪后的图像。为了去除后向散射和背景辐射对实验结果的影响,搭建一套基于距离选通ICCD的激光主动照明系统,采集不同散斑强度的主动照明图像进行实验。结果表明该方法拥有比经典的Lee、Frost和Kuan算法更好的散斑噪声抑制效果,同时运算时间在毫秒量级,满足激光主动成像算法实时性的需求。
To suppress speckle noise efficiently and achieve less time consuming in laser active imaging, a denoising method based on spectrum-domain constraint in signal subspace is proposed. Homomorphic transform is performed to convert the multiplicative noise to additive noise. The noisy image is decomposed using singular value decomposing to estimate the dimension of signal subspace. Based on the dimension, the covariance matrix of the noisy image is decomposed using eigenvalue decomposing to estimate the covariance of speckle noise with the eigenvector in noise subspace. Mter that the denoising estimating matrix is computed with the eigenvector in signal subspace and is convolved with the noisy image. Inverse homomorphic transform is carried out and the denoised image is obtained. In order to eliminate the effect of backscatter and background radiation, a laser active imaging system based on range gating ICCD is constructed. The experiment is performed using images with speckle noise in different levels and the results show that compared with classical Lee, Frost and Kuan filters, the proposed method has advanced denoising performance and the computing time is in millisecond level, which meets the requirement of real-time operation for laser active imaging.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2013年第11期217-222,共6页
Chinese Journal of Lasers
基金
吉林省重大科技攻关专项(20120615)
关键词
图像处理
信号子空间
谱域约束
散斑噪声
距离选通
image proccessing
signal subspace
spectrum-domain constraint
speckle noise
range gating
