Error while compressing the image using dct2()

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0 个投票

Hi!

I am trying to compress image using DCT :

close all;
x=imread('image.jpeg');
figure,imshow(x);
F=dct2(x);
figure,imshow(F*0.01);
ff=idct2(F);
figure,imshow(ff/255);
[r,c]=size(x);
DF=zeros(r,c);
DFF=DF;
IDF=DF;
IDFF=DF;
depth=4;
N=8;
for i=1:N:r
  for j=1:N:c
    f=original(i:i+N-1,j:j+N-1);
    df=dct2(f);
    DF(i:i+N-1,j:j+N-1)=df;
    dff=idct2(df);
    DFF(i:i+N-1,j:j+N-1)=dff;
    
    
    df(:,N:-1:depth+1)=0;
    df(N:-1:depth+1,:)=0;
    IDF(i:i+N-1,j:j+N-1)=df;
    dff=idct2(df);
    IDFF(i:i+N-1,j:j+N-1)=dff;
   end
end
figure,imshow(DF/255);
figure,imshow(DFF);
A=DFF/255;
figure,imshow(A);
imwrite(A,'img.jpeg');
B=IDFF/255;
imwrite(B,'img_comp.jpeg');
figure,imshow(B);

Got this code from Online sources.

I am getting the following errors:

Matrix dimensions must agree.
Error in dct (line 76)
  b = W .* fft(y);
Error in dct2 (line 50)
    b = dct(dct(arg1).').';
Error in image_compression2 (line 4)
F=dct2(x);