Otsu法是图像阈值分割中的经典算法之一，在图像处理中得到广泛的应用。针对原始2维Otsu法直方图区域划分上的缺陷和运算速度慢的缺点，分析了适用于SAR图像相干斑乘性噪声的直方图区域划分方法，提出了一种更符合实际图像模型的阈值选取准则。实验结果表明，该改进算法的分割效果良好，运算速度也有很大提高。

As one of the classic threshold methods for image segmentation, Otsu algorithm has been widely applied in image processing. Based on the analysis of the original 2D Otsu which has the disadvantages such as histogram area partition and time consuming, this paper introduces a new method of area partition in terms of speckle noise in SAR images, and brings forward a new rule of threshold selection which fits the image model better. The experiments show that the segmentation effect of the improved algorithm is better and its computational speed has been greatly improved.