数字图像处理实验（6）：PROJECT 04-02，Fourier Spectrum and Average Value

实验要求：

Objective:
To observe the Fourier spectrum by FFT and the average value of an image.
Main requirements:
Ability of programming with C, C++, or Matlab.
Instruction manual:
(a) Download Fig. 4.18(a) and compute its (centered) Fourier spectrum.
(b) Display the spectrum.
(c) Use your result in (a) to compute the average value of the image.

实验中我们要观察图像进行FFT后的傅里叶频谱图，并且输出其均值。

代码：

%%close all;clc;clear all;%%img = imread('gray_image.jpg');imshow(img);title('original image');% 计算傅里叶变换img_F = fft2(img);[M, N] = size(img);s = sum(abs(img_F(1:M, 1:N)));  % 行求和s = sum(s);     % 列求和ave = s / (M * N);disp(['average value of image is: ',num2str(ave)]);S = log(1 + abs(img_F));% figure;% plot(S);% title('二维图像显示幅度谱');x = 0:1:255;y = 0:1:255;[x, y] = meshgrid(x, y);figure;mesh(S);title('三维图像显示幅度谱');img_Q = angle(img_F);% figure;% plot(img_Q);% title('二维图像显示相位谱');x = 0:1:255;y = 0:1:255;[x, y] = meshgrid(x, y);figure;mesh(img_Q);title('三维图像显示相位谱');

实验结果：

上图是原始图像。

上图是FFT之后3维幅度谱。

上图是FFT之后3维幅度谱。

均值。