基于系统噪声抑制的ScanSAR辐射校正方法

Radiometric correction algorithm for ScanSAR scalloping based on reduction of system noise

SAR回波数据中难免会存在系统噪声,传统的成像处理和辐射校正均不考虑系统噪声的影响,这会影响SAR图像的辐射质量。特别是对ScanSAR而言,在对扇贝效应进行去除时,在低信噪比区域,如果不考虑系统噪声,会使得校正后存在很大的残余误差,不仅影响图像可视化效果,同时导致辐射精度的下降。定量分析了系统噪声在辐射校正中的影响,介绍了系统噪声的抑制方法和噪声估计手段,在此基础上提出了基于系统噪声抑制的ScanSAR方位向辐射校正整体方案。算法在幅度图像上对系统噪声进行了抑制,并在图像域进行了方向图补偿。经实验验证,确实提高了ScanSAR扇贝效应的校正结果,提升了图像质量。

SAR raw data is disturbed by additive system noise which influences the SAR image intensity, however, Traditional radiometric correction methods usually ignore the effects of system noise, Particularly in the case of ScanSAR, sys- tem noise is added to its own scalloping effect. In low backscatter area, radiometric correction without considering system noise will remain a residual noise which will deteriorate the quality of image. In this paper, we first quantize the effect of system noise in ScanSAR radiometric correction, and then introduce a method to estimate system noise and reduce it. Eventually, we propose a method to correct scalloping in ScanSAR system based on reduction of system noise. It reduces noise and correct antenna pattern in amplitude image. Simulations and application of the algorithm in real ScanSAR data processing show that scalloping pattern is removed and image quality is improved.