i have a code for dct watermarking wherin the watermark is getting embedded but the watermark is an invisible watermark.....wat changes do i hve to make to make the watermark visible?

clc; clear all; start_time=cputime; k=50; blocksize=8; file_name1='C:\Users\Public\Pictures\Sample Pictures\Lighthouse.jpg';

        %cover_object=double(rgb2gray(imread(file_name1)));

cover_image = imread(file_name1);

        cover_object = double(cover_image(:,:,1));  %red plane

Mc=size(cover_object,1);

Nc=size(cover_object,2);

max_message = floor(Mc/blocksize) * floor(Nc/blocksize);

        %max_message=Mc*Nc/(blocksize^2);
   
  file_name2='C:\Users\Public\Pictures\Sample Pictures\desert1.jpg';

message=double(rgb2gray(imread(file_name2)));

Mm=size(message,1);

Nm=size(message,2);

message=round(reshape(message,Mm*Nm,1)./256); if (length(message) > max_message)

error('Message too large to fit in Cover Object')

        end

message_pad=ones(1,max_message);

message_pad(1:length(message))=message; watermarked_image_r=cover_object; x=1;

y=1;

for (kk = 1:length(message_pad)) dct_block=dct2(cover_object(y:y+blocksize-1,x:x+blocksize-1)); if (message_pad(kk) == 0) if (dct_block(5,2) < dct_block(4,3))

temp=dct_block(4,3);

dct_block(4,3)=dct_block(5,2);

dct_block(5,2)=temp; end elseif (message_pad(kk) == 1) if (dct_block(5,2) >= dct_block(4,3))

temp=dct_block(4,3);

dct_block(4,3)=dct_block(5,2);

dct_block(5,2)=temp; end end if dct_block(5,2) > dct_block(4,3)

if dct_block(5,2) - dct_block(4,3) < k

dct_block(5,2)=dct_block(5,2)+(k/2);

dct_block(4,3)=dct_block(4,3)-(k/2);

            end

else

if dct_block(4,3) - dct_block(5,2) < k

dct_block(4,3)=dct_block(4,3)+(k/2);

dct_block(5,2)=dct_block(5,2)-(k/2); end end watermarked_image(y:y+blocksize-1,x:x+blocksize-1)=idct2(dct_block); if (x+blocksize) >= Nc

x=1;

y=y+blocksize; else x=x+blocksize; end end watermarked_image_int=uint8(watermarked_image);

            watermarked_red = cast(watermarked_image, class(cover_image));

            watermarked_image = cat(3, watermarked_red, cover_image(:,:,[2 3]));
      imwrite(watermarked_image,'C:\Users\Public\Pictures\Sample Pictures\dct1_watermarked_circuit.jpg','jpg');
   
  elapsed_time=cputime-start_time,
   
  subplot(2,1,1);imshow(cover_image,[]);title('Original Image')

subplot(2,1,2);imshow(watermarked_image,[]);title('Watermarked Image')