Consider the following:
im = double(imread('lena.bmp')); subplot(1,3,1), imshow(im,), title('original'); t1 = dct2(im); subplot(1,3,2), imshow(log(abs(t1)+1),), title('DCT transform'); t2 = dct2(t1); subplot(1,3,3), imshow(t2,), title('DCT(DCT) transform');
the output is shown below:
Could anyone explain why the result of the second order DCT is similar to the original image?
Thanks in advance!
P.S. The same thing happens with every 2N'th DCT.