空域的卷积等于频率域的乘积例子

clear; close all;clc;

img = imread('flower.tif');
img = imresize(img,[511 511]);
img = double(img);

img_fft = fftshift(fft2(img));
figure;mesh(real(img_fft));
filter = [1 1 1; 1 -8 1; 1 1 1];
filter_fft_pad = padarray(filter,[(size(img,1)-3)/2 (size(img,1)-3)/2]);
filter_fft = fftshift(fft2(filter_fft_pad));

figure;mesh(real(filter_fft_pad));

rt = fftshift(ifft2(fftshift(filter_fft.*img_fft)));
figure;
imshow(uint8(real(rt)));

%filter = rand(3,3);

% rt is almost same with img_conv
img_conv = conv2(img,filter,'same');
figure;
imshow(uint8(img_conv));
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作者：zhoucy163 
来源：优快云 
原文：https://blog.youkuaiyun.com/jiao_zhoucy/article/details/49765223 
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