目前常用的遥感薄云去除法是同态滤波法,但由于所采用的滤波器的局限性,传统的同态滤波法只能去除处于低频区域的云,而对处于高频区域的云则没有处理效果。因此在研究传统同态滤波算法,选取性能最佳的频域滤波器对图像进行处理的基础上,引入了空域3×3中值滤波,用像素点3×3邻域内9个像素点的中值来代替该点的像素值,旨在对前者无法去除的高频突变云区进行处理。而后结合主观视觉和客观统计分析两方面对仿真结果进行评价,经分析表明,用该方法处理过的影像在信息未受损失的情况下,高频突变云有所减少,达到了预期目的。

The traditional homomorphic filtering frequently used in cloud-removing has effect on the clouds in low-frequency region,but is not effective for those in high-frequency region,because of the limitation of high-pass filters it used. Based on the study of the traditional homomorphic algorithm,the most effective high-pass filter in frequency domain is adopted. And then,in order to remove the cloud in high-frequency region,a popular nonlinear spatial filter,3×3 median filter,is introduced,which replaces the value of the central pixel by the median of the gray levels in the 3×3 neighborhood of that pixel. At last,analysis of the experiment results in vision and statistics is carried out,which shows that the improved method is effective in removing the cloud in high-frequency region.