opencv实现傅里叶变换,傅立叶变换是把图像从空间域转化到频率域的变换。空间域：一般的情况下，空间域的图像是f（x，y）=灰度级（0-255），形象一点就是一个二维矩阵，每个坐标对应一个颜色值。频率域：频率：对于图像来说可以指图像颜色值的梯度，即灰度级的变化速度，幅度：可以简单的理解为是频率的权，即该频率所占的比例：能量=幅度（可能不太准确），变换结果为F（u，v），F代表幅度值，u代表x方向的频率，v代表y方向的频率(Fu Liye transform is the transformation of image from space domain to frequency domain. Spatial domain: in general, the image in the spatial domain is f (x, y) = gray level (0-255), and the image is a two-dimensional matrix, and each coordinate corresponds to a color value. Frequency domain: frequency: for images can refer to gradient image color values, i.e. the rate of change of gray level range can be simply understood as the right that the frequency of the frequency, the proportion of energy (= range may not be accurate), transform results for F (U, V), F on behalf of amplitude values, u represents the direction of X V frequency, Y direction frequency)