The characteristic difference between targets and clutter is analyzed.Considering the gray in-tensity distribution of ship target,and its shape difference compared to the clutter,in this paper,a new algo-rithm is presented based on gray correlation.The algorithm utilizes the strong gray intensity correlation in the ship target.Also,the joint gray intensity distribution(JPDF)using 2D joint log-normal distribution of a pixel with neighboring pixels in the clutter is modeled,which can be used for correlation-based joint CFAR detection.Using this algorithm,the false alarms caused by speckle and local background non-homogeneity can be greatly reduced.The detection performance is much better.%分析了中高分辨率 SAR海洋图像的目标和海杂波特点，利用了 SAR海洋图像中舰船目标的灰度相关性、形状特性以及舰船目标与背景杂波的信杂比特性，提出了一种基于灰度相关性的联合 CFAR舰船检测算法。算法综合利用了舰船目标内部相邻像素间的灰度强相关性和舰船目标和海杂波的信杂比，建立了海杂波区域内相邻像素间灰度值的二维对数正态分布来实现联合 CFAR检测。该算法能够改善斑点噪声和背景局部不均匀对检测带来的虚警，检测效果相比于传统检测算法更加优越。
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