数字图像处理，灰度化、邻域平均、中值滤波、傅里叶变换、轮廓提取-Digital image processing, gray, neighborhood average, median filtering, FFT, contour extraction

针对于非局部平均算法的计算量过大的缺点，提出了一种基于FFT和SSI的快速非局部平均算法。-For nonlocal average algorithm of the shortcomings of the large amount of calculation, this paper proposes a fast and nonlocal average algorithm based on FFT and SSI.