%載入圖像
RGB = imread('autumn.tif');
figure(1);
imshow(RGB);
%將真彩圖轉(zhuǎn)換為灰度圖
I = rgb2gray(RGB);
figure(2);
imshow(I);
%進(jìn)行余弦變換
J = dct2(I);
figure(3);
imshow(log(abs(J)),[]);
colormap(jet(64));
colorbar;
%將DCT變換值小于11的元素設(shè)為0
J(abs(J)<11) = 0;
%進(jìn)行余弦反變換
K = idct2(J)/255;
figure(4);
imshow(K)