%% 自己設定頻域的濾波視窗
girl=imread('F:\Users\*****\Pictures\CGS_stripe1.bmp');
girl=rgb2gray(girl);
girl=im2double(girl);
subplot(1,2,1);imshow(girl);%顯示原始影象
title('原始影象'); 
G=fft2(double(girl));% 二維傅立葉變換
G=fftshift(G);%象限轉換
subplot(1,2,2);imshow(log(abs(G)+1),[ ]);%顯示原始影象頻譜圖
title('原始影象頻譜圖');figure;
 
%構造理想低通濾波器，並用它濾波
[height  width]=size(G);
H(1: height,1: width)=0.9;
x0= height/2; y0= width/2;%確定原點
for x=1:height
    for y=1:width
        if(sqrt((x- x0)*(x- x0)+(y-y0)*(y-y0))>15) %確定濾波半徑
            H(x,y)=1;
        end
        F(x,y)=G(x,y)*H(x,y);
    end
end
imshow(log(abs(F)+1),[ ]);%顯示中間影象頻譜圖
title(
 
'中間影象頻譜圖');
g=ifft2(F);% 傅立葉反變換
figure;imshow(abs(real(g)),[ ]);%顯示處理後的影象
title('處理後的影象');