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)
imshowpair(I,I_recover,'montage')
you see, I and I_recover are the same
