How can I extract only the compressed image from that code? (not the reconstructed one)

I followed the link and i got the reconstructed one but i also need to extract the compressed one : https://www.mathworks.com/help/images/discrete-cosine-transform.html

Answer 1

[xingxingcui]

hi, the reconstructed one is you want the compressed one.

or use B to recover origin image.

I = imread('cameraman.tif');
I = im2double(I);
T = dctmtx(8);
dct = @(block_struct) T * block_struct.data * T';
B = blockproc(I,[8 8],dct);
invdct = @(block_struct) T' * block_struct.data * T;
I_recover = blockproc(B,[8 8],invdct);

figure;
err = immse(I,I_recover)

err = 1.1837e-30

imshowpair(I,I_recover,'montage')

you see, I and I_recover are the same

[Khaled]

ok thank you but the image has the same size so we got the image after decompression my goal is to get th image before decompression