Phụ lục
311
if (exist(infile)==2)
a = imread(infile);
figure('Name','Input image');
imshow(a);
else
warndlg('The file does not exist.',' Warning ');
im=[];
return
end
if isrgb(a)
if isa(a(:,:,1),'uint8')
red = double(a(:,:,1));
green = double(a(:,:,2));
blue = double(a(:,:,3));
red_dct=dct2(red);
green_dct=dct2(green);
blue_dct=dct2(blue);
red_pow = red_dct.^2;
green_pow = green_dct.^2;
blue_pow = blue_dct.^2;
red_pow=red_pow(:);
green_pow=green_pow(:);
blue_pow=blue_pow(:);
[B_r,index_r]=sort(red_pow);
[B_g,index_g]=sort(green_pow);
[B_b,index_b]=sort(blue_pow);
index_r=flipud(index_r);
index_g=flipud(index_g);
index_b=flipud(index_b);
im_dct_r=zeros(size(red));
im_dct_g=zeros(size(green));
im_dct_b=zeros(size(blue));
for ii=1:coeff
im_dct_r(index_r(ii))=red_dct(index_r(ii));
im_dct_g(index_g(ii))=green_dct(index_g(ii));
im_dct_b(index_b(ii))=blue_dct(index_b(ii));
end
im_r=idct2(im_dct_r);
im_g=idct2(im_dct_g);
im_b=idct2(im_dct_b);
